Dilated Common Bile Duct Research Articles

S2860 Role of Endoscopic Ultrasound in the Diagnosis of Extrapulmonary, Disseminated Coccidiomycosis as a Cause of Recurrent Ascites and Acute Pancreatitis

Introduction: Coccidiomycosis (Valley Fever) is an endemic fungal infection in the Southwestern United States caused by Coccidiodes immitis and posadassi. Extrapulmonary involvement is very rare (approximately < 1%) and diagnosis can be challenging as the yield for culture detection is low. We present the utility of endoscopic ultrasound (EUS) with fine needle aspiration (FNA) in diagnosing a rare case of extrapulmonary coccidiomycosis with recurrent pancreatitis. Case Description/Methods: 44 year old male with history of hypertension, diabetes mellitus type 2, alcoholic cirrhosis with ascites was referred to gastroenterology clinic for evaluation of recurrent pancreatitis of unclear etiology. Prior to his third admission for recurrent pancreatitis, his ascites was well-controlled on diuretics and a low sodium diet. Labs were notable for hemoglobin of 12.7 gm/dl, platelets 117 K/mL, creatinine 1.03 mg/dl, triglycerides 116 mg/dL, lipase 124U/L, bilirubin 2.2 mg/dL and otherwise normal hepatic function panel. His alcohol level and Phosphatidylethanol were negative. Computed tomography of the abdomen and pelvis without contrast showed acute interstitial pancreatitis. Ultrasound showed a normal biliary system without gallstones or common bile duct dilation (CBD) and ascites. Patient underwent multiple paracentesis before and after these hospitalizations with normal cell counts, negative acid-fast bacillus, bacterial and fungal cultures, and serum-albumin gradient consistent with portal hypertension. Endoscopy showed small, non-bleeding esophageal varices in distal esophagus, portal hypertensive gastropathy and no gastric varices. EUS was performed revealing multiple rounded, hypoechoic lymph nodes (LN) in periportal area and peripancreatic area with largest measuring 2 cm and normal pancreatic parenchyma, pancreatic duct, and CBD. FNA biopsy of the LN was positive for granulomas with fungal organisms consistent with Coccidioides and negative for malignancy. The patient was subsequently started on oral fluconazole 800 mg daily. (Figure) Discussion: EUS with FNA is an underutilized but highly valuable diagnostic method for extrapulmonary Coccidiomycosis. To our knowledge, this is one of the first cases in which EUS was utilized to diagnose disseminated Coccidiomycosis with lymphadenopathy as an etiology of recurrent pancreatitis. In this case, biopsy of peri-pancreatic lymphadenopathy from coccidiodes was deemed the etiology of recurrent pancreatitis by compressing pancreaticobiliary system.Figure 1.: Top: EUS revealed multiple lymph nodes in the periportal and peripancreatic area. Bottom: EUS-guided fine needle biopsy was performed on the largest lymph node measuring 2 cms.

Choledochoceles in children: The elephant abnormality

A choledochocele is a rare congenital abnormality of the extrahepatic bile duct characterised by localised dilatation of the distal common bile duct within the wall of the duodenum. We present two children with a long history of undiagnosed abdominal pain and subtle signs of cholestasis. Specific investigations included magnetic resonance cholangiopancreatography (MRCP) that led to a possible diagnosis of choledochocele, and then confirmatory cholangiograms (ERCP and open). Both children required intervention to unroof the dilatation allowing improved pancreato-biliary drainage and complete resolution of symptoms. Elephants have no gallbladder, instead they have a localised dilatation of the distal common bile duct within the wall of the duodenum – analogous to the situation described here. • Choledochoceles may have non-specific symptoms making them difficult to suspect. • Cholangiogram is the gold standard to confirm the diagnosis. • Drainage of the choledochocele into the duodenum resolves symptoms and can be done endoscopically or surgically. • Biopsy should always be taken as a malignancy risk exists, at least in adults.

S1712 Choledochal Cyst Mimicking the Gallbladder With a Surprising Twist

Introduction: Choledochal cysts are congenital rarities and often a pediatric diagnosis but 20% go undetected until adulthood. Etiology remains unclear but an obstructed common bile duct (CBD) has been identified as a pathogenic feature. We present a rare case of choledochal cyst initially mimicking the gallbladder in an elderly female. Case Description/Methods: A 90-year-old woman presented to the hospital for abdominal pain and unintentional weight loss. Past medical history was notable for breast cancer and colorectal cancer status post resection. Liver function tests and pancreatic markers were normal with mildly elevated alkaline phosphatase. CT abdomen and pelvis revealed a 2.8 cm dilated common bile duct (CBD), choledocholithiasis, pancreatic duct dilation and absent gallbladder. Patient however denied undergoing a cholecystectomy. Given the discrepancy of imaging and history, an abdominal ultrasound was performed demonstrating large gallstones in the gallbladder with normal CBD size. Endoscopic ultrasound (EUS) revealed a 28x26 mm mass in the ampulla (Figure). FNB was performed. The distal CBD measured 7 mm with a 35 mm proximal CBD consistent with a choledochal cyst full of large stones. Pancreatic duct measured up to 8 mm. Gallbladder was confirmed to be surgically absent. ERCP was performed which revealed an infiltrative 3-4 cm mass at the major papilla. Pancreatic and biliary sphincterotomies were performed and metal stents were placed in the ventral pancreatic duct and CBD. Biopsies taken revealed pancreatic adenocarcinoma. The following month, hepatobiliary surgery performed a Whipple procedure (pancreaticoduodenectomy). Pathology findings confirmed pancreatic adenocarcinoma with metastasis to one of twelve lymph nodes. Patient was arranged to follow up with outpatient oncology. Discussion: Choledochal cysts can be an elusive diagnosis in elderly adults given its rarity, prevalence in children, and common presentation of vague abdominal pain. Choledochal cyst should be part of the differential diagnosis regardless of patient age especially in cases of accompanying weight loss due to its increased risk of biliary malignancy. In our case, the patient was found to have choledochal cyst misrepresented as the gallbladder and incidentally found to have pancreatic adenocarcinoma. Additionally, patients may be unreliable historians leading to misinterpretation of imaging results. Further investigation is therefore warranted in these perplexing cases for an accurate diagnosis and appropriate management.Figure 1.: A. Ampullary mass B. Pancreatic duct dilation C. Choledochal cyst. D Post ERCP.

S1792 Painless Obstructive Jaundice: Pancreatic Adenocarcinoma Cannot Be Excluded

Introduction: Autoimmune pancreatitis (AIP) is a chronic inflammatory condition typically presenting with abdominal pain, jaundice and weight loss. AIP is an uncommon cause of pancreatitis and diagnosis may be challenging, but it is highly responsive to corticosteroids. We present a case of painless obstructive jaundice complicated by a mass on the pancreatic head. Case Description/Methods: A 57-year-old Indian male with no past medical history presented with vague abdominal pain, pruritus, and clay colored stools. Vital signs were unremarkable and laboratory investigations revealed alkaline phosphatase 515 U/L, alanine transaminase 732 IU/L, and total bilirubin 7.6 mg/dL. The patient underwent a right upper quadrant ultrasound which showed an enlarged gallbladder and dilated common bile duct (1.9 cm) down to the level of the pancreatic head. An endoscopic ultrasound (EUS) revealed a 3.2 x 3.7 cm hypoechoic mass in the head of the pancreas obstructing the bile duct, 2 enlarged lymph nodes in the area near the bile duct, marked bile duct dilation, and an enlarged sludge-filled gallbladder. Of note, unlike most ductal tumors the pancreatic duct upstream of the mass was not dilated. Fine needle aspiration (FNA) was unsuccessful due to the obstruction by the lymph nodes. Endoscopic retrograde cholangiopancreatography (ERCP) showed stricture of bile duct consistent with a pancreatic head mass, and was stented. Abdominal and pelvic computed tomography (CT) confirmed a 3 cm pancreatic head mass. Pathology result from the attempted FNA was inconclusive. Further labs revealed normal IgG4 and CA 19-9 level of 194; indicative of possible pancreatic malignancy. The patient developed jaundice, scleral icterus and rapid weight loss. EUS with FNA with repeat biopsies revealed rare degenerated epithelial cells. The patient was treated with high dose steroids, with planned pancreaticoduodenectomy. Follow-up CT revealed resolution of the pancreatic mass and was confirmed by repeat EUS/ERCP and normal CA 19-9 level. Discussion: Although painless obstructive jaundice with a pancreatic mass is a typical presentation for a pancreatic neoplasm; it is not the only possible diagnosis. Despite biochemical and radiographic evidence suggesting a malignancy; if AIP remains in the differential, a trial of steroids may be warranted to avoid unnecessary surgical intervention and associated morbidity.

S3157 Respiratory Syncytial Virus-Associated Hepatitis in Pregnancy

Introduction: Respiratory syncytial virus (RSV) predominantly affects children and typically manifests as an upper respiratory tract infection. Primary RSV infection in immunosuppressed adults may increase risks of disseminated infection manifesting as RSV hepatitis. RSV hepatitis may present with fever, abdominal pain, nausea, vomiting, jaundice, coagulopathy, and elevation of transaminases. Case Description/Methods: A 29-year-old woman with 10 weeks of pregnancy, history of anemia and vitamin B12 deficiency was admitted to the hospital for fatigue, intractable nausea, vomiting and inability to tolerate oral intake. She denied respiratory symptoms. She was taking prenatal multivitamins but denied starting new medications or supplements. At presentation, her vital signs and clinical exam were unremarkable with uterine fundus palpable just above the pubic bone. Initial laboratory work up revealed elevated liver enzymes with AST 497 U/L, ALT 712 U/L, normal total bilirubin and ALP. Abdominal ultrasound (US) demonstrated cholelithiasis without evidence of cholecystitis or common bile duct dilation. Subsequent workup including an acute hepatitis panel; CMV, EBV serology; stool H. pylori testing; and autoimmune workup was negative. HSV IgM serology was indeterminant. A respiratory viral molecular panel by PCR was positive for RSV. Abdominal US with doppler showed normal hepatic and portal vessel blood flow and magnetic resonance cholangiopancreatography was negative for choledocholithiasis. She was treated supportively with intravenous fluids, antiemetics and close fetal monitoring. Her liver enzymes peaked on hospital day 4 with AST 863 U/L, ALT 1214 U/L, total bilirubin 1.1 mg/dL. By hospital day 5, her symptoms improved, and she was discharged. At 5 week follow up, AST and ALT improved to 62 U/L and 82 U/L, respectively. Her elective laparoscopic cholecystectomy was deferred until after delivery due to symptom resolution and absence of acute cholecystitis. Discussion: Disseminated RSV a rare manifestation in immunocompromised individuals. Clinical presentation may be atypical, creating diagnostic challenges. Liver biopsy is rarely required to establish the diagnosis. RSV hepatitis is typically self-limited and can be treated with supportive care as antiviral agents have no proven efficacy. A high index of suspicion is required for early identification of RSV hepatitis as timely supportive care may prevent progression to acute liver failure. Table 1. - Laboratory Testing Done to Investigate Emesis Etiology Caption Laboratory Test Reference Range and Units Results Liver Function Tests Alanine aminotransferase (ALT) 0-34 U/L 990 (H) Aspartate aminotransferase (AST) 15-46 U/L 750 (H) Alkaline phosphatase (ALP) 38-126 U/L 89 (N) Total bilirubin 0.2-1.3 mg/dL 1.4 (H) Total Protein 6.3-8.2 g/dL 6.4 (N) Albumin 3.5-5.0 g/dL 3.6 (N) Coagulation Studies Prothrombin time (PT) 9.0-12.0 10.9 (N) International normalized ratio (INR) 0.9-1.1 1.0 (N) Viral Serologies Hepatitis A, IgM Non-reactive Non-reactive Hepatitis B, core IgM Non-reactive Non-reactive Hepatitis B, surface antigen Non-reactive Non-reactive Hepatitis C antibody Non-reactive Non-reactive Hepatitis E antibody Non-reactive Non-reactive Human immunodeficiency virus 1 and 2 antibody/antigen Non-reactive Non-reactive Herpes simplex virus 1 and 2 IgM < =0.89 0.96 (intermediate) Cytomegalovirus quantitative PCR Non-reactive Not detected Epstein Barr virus, IgM Not detected Not detected Influenza A, antigen Not detected Not detected Influenza B, antigen Not detected Not detected Respiratory Syncytial Virus Not detected Detected Autoimmune liver disease panel Liver-Kidney Microsome-1 Antibody IgG (Anti-LMK) 0.0 - 24.9 U 0.8 (N) Antinuclear antibody (ANA) titer < 1:80 < 1:80 (N) Anti-smooth muscle antibody (ASMA) 0-19 Units 6 (N) Antimitochondrial antibody (AMA) 0.0-24.9 Units 2.4 (N) Miscellaneous Rapid plasma regain (RPR) Negative Negative Total Creatinine Kinase (CK) 30-170 U/L < 20 (L) H. pylori antigen Negative Negative - H: High; N: Normal; L: Low.

S3167 Sickle Cell Hepatopathy in a Young Patient With Markedly Elevated Bilirubin

Introduction: The vaso-occlusive events that characterize a sickle cell pain crisis are known to affect multiple organ systems. Sickling in the hepatic sinusoids leads to ischemia, cholestasis, and sequestration, which collectively contribute to acute liver dysfunction often referred to as sickle cell hepatopathy (SCH). As one of the rarer complications of sickle cell disease (SCD) SCH may go under-recognized. Here we present a case of acute sickle cell hepatic crisis, a subset of SCH, with the aim of increasing the available literature on this important topic. Case Description/Methods: A 20-year-old male with a history of sickle cell disease (SCD) presented for evaluation of right upper quadrant abdominal pain. Vitals signs were normal and physical examination was notable for jaundice and right upper quadrant abdominal tenderness. Labs revealed mildly elevated liver enzymes and elevated direct bilirubin of 34 mg/dL. Abdominal sonography revealed findings suggestive of hepatitis and common bile duct dilation, with suggestion of gallbladder wall thickening. MRCP showed mild intrahepatic and extrahepatic bile duct dilation, as well as splenic hemosiderosis. The common bile duct was 0.9 cm in diameter. Hepatitis A, B, C, as well as HIV, CMV, and herpes screening tests were nonreactive. An ultrasound-guided liver biopsy then revealed features of an acute sickle cell hepatic crisis, including distended sinusoids with erythrocyte sludging. With two days of symptomatic treatment alone, the patient had improvement in his direct bilirubin to 7 mg/dL and was discharged after complete resolution of his symptoms. (Figure) Discussion: Acute sickle cell hepatic crisis (ASCHC), a subset of sickle cell hepatopathy (SCH), is often difficult to diagnose for a multitude of reasons including vague presenting symptoms and clinician unfamiliarity with the disease. While treatment guidelines are lacking with regards to the specific treatment for ASCHC, it is worth noting that in our case clinical and assay improvement was seen after several days of symptomatic treatment alone. Although not present in our case, ASCHC has the potential to be concurrent with a more severe form of the disease known as sickle cell intrahepatic cholestasis (SCIC), which if untreated can be fatal. Both ASCHC and SCIC can present with jaundice, as in our patient, but only SCIC progresses to organ failure. As more cases are described, the optimal treatment modalities for these rarer complications of sickle cell disease will only increase.Figure 1.: Liver parenchyma with dilated sinusoids, readily visualized sickled red blood cells (right side of the image) and canalicular cholestasis (brown pigment on the left side of the image).

S1841 The Curious Case of CA 19-9 in Mirizzi Syndrome

Introduction: Mirizzi Syndrome (MS) is a rare complication of gallstone disease, caused by an obstructing stone in the cystic duct or the gallbladder neck, leading to obstruction of the common hepatic duct. This case discusses the utility of EUS in improving diagnostic yield of MS and the importance of cancer screening in these patients. Case Description/Methods: A 44-year-old male with a history of gastritis presented with right upper quadrant (RUQ) abdominal pain, jaundice, and scleral icterus for one week. On exam, the patient was afebrile with mild RUQ abdominal tenderness. Labs showed a total bilirubin of 5.4 mg/dL, AST of 66 U/L, ALT of 228 U/L, and a total alkaline phosphatase of 159 U/L. Ultrasound demonstrated intra- and extrahepatic biliary dilation with suggestion of a shadowing stone within the common bile duct (CBD). The gallbladder wall was thickened with trace pericholecystic fluid. MRCP showed a 15 mm calculus presumed to be in the CBD, with a 16 mm CBD dilation. ERCP showed a filling defect in the midportion of the CBD, and a CBD stent was placed. Due to these findings, a CA 19-9 antigen was drawn, measuring 3038 U/mL. EUS was then performed, which visualized a cystic duct stone partially extending into the CBD– a finding consistent with MS. An enlarged lymph node was visualized in the porta hepatis region. FNA of the lymph node as well as CBD brushings from the ERCP were both negative for malignant cells. The patient was discharged and underwent a cholecystectomy two weeks later. Surgical findings were consistent with MS and a 20 mm stone was removed with the gallbladder. The intraoperative frozen section of the gallbladder was negative for malignant cells. (Figure) Discussion: Initial evaluation for MS should include an ultrasound or CT scan, followed by MRCP. The pooled sensitivity of MRCP for detecting CBD stones is around 87%. While MRCP is often used to diagnose MS, the anatomy may not be well visualized due to the proximity of the cystic duct to the CBD. EUS has a pooled sensitivity of 97% in detecting a CBD stone and can better visualize the biliary tract anatomy, aiding in diagnosis. Diagnosis of MS prior to surgery can be helpful in avoiding biliary tract injuries. MS evaluation should also include screening for malignancy, as MS has an association with gallbladder cancer. While elevated CA 19-9 levels are concerning for malignancy, they can also be seen in chronic benign biliary obstruction. It is important to obtain a CA 19-9 level when suspecting MS, both before and after stone removal.Figure 1.: A. MRI: A T2-weighted image showing a 15 mm filling defect (white arrow) within the cystic duct, partially extending into the common bile duct, consistent with an obstructing stone. Intrahepatic and extrahepatic biliary dilation is also seen. B. Endoscopic ultrasound: An ovoid, hyperechoic structure, measuring 11 mm x 15 mm, with shadowing suggestive of a gallstone at the level of the cystic duct and compression of the common bile duct. C. Endoscopic ultrasound: An irregularly contracted gallbladder (black arrow) with adjacent dilated common bile duct. D. Endoscopic ultrasound: Fine needle aspiration of an enlarged lymph node with well defined margins in the porta hepatis region, measuring 20 mm x 15 mm in maximal cross-sectional diameter. Color Doppler imaging was utilized prior to needle puncture to confirm a lack of significant vascular structures within the needle path.

S3125 Overlapping Hepatotoxicity and Colitis Associated With Immune Checkpoint Inhibitors

Introduction: Immunotherapy with immune checkpoint inhibitors (ICIs) has become the standard of care for many solid-organ and hematologic malignancies. Gastrointestinal toxicities are common side effects that typically occur 6 weeks after starting ICI therapy. Overlapping hepatotoxicity and colitis associated with ICIs is rare and may be overlooked, resulting in high mortality. Case Description/Methods: A 73-year-old man with metastatic squamous cell carcinoma (SCC) of the head and neck presented with intermittent, diffuse abdominal discomfort, bloating and painless non-bloody diarrhea (up to 6 episodes daily) triggered by meals. Symptom onset was 6 weeks after starting pembrolizumab for head and neck SCC. Pembrolizumab therapy was held, and supportive therapy with proton pump inhibitors, antacids and antidiarrheals provided partial symptom relief. Laboratory work up showed elevated AST 132 U/L, ALT 220 U/L, ALP 851 U/L and normal total bilirubin. ANA was elevated with titer 1:80, with normal total IgG (699.5 mg/dL) and negative serologies for anti-smooth muscle antibody, CMV, EBV, and HSV. Abdominal CT with contrast showed a dilated common bile duct (CBD) of 11 mm and a new curvilinear filling defect in the distal CBD, without choledocholithiasis. MRCP revealed mildly dilated intrahepatic biliary ducts, CBD dilation (13 mm), and an ovoid 8mm soft tissue nodule in the periampullary duodenum. Upper endoscopy was nondiagnostic. At this time, the patient’s symptoms improved, but there was high suspicion of grade-2 ICI-associated hepatitis (ICIH). Percutaneous liver biopsy showed interlobular bile duct injury with intraepithelial lymphocytes and neutrophils and a neutrophilic ductular reaction consistent with ICIH. Serial lab work demonstrated improvement of liver enzymes, with AST 77 U/L, ALT 69 U/L and ALP 667 U/L at 60 days after initial labs. Diarrhea resumed, up to 6 episodes per day, consistent with the Common Terminology Criteria for Adverse Events diagnosis of ICI-related colitis (ICIC). Initial supportive therapy failed to improve diarrhea; thus, a prednisone taper was started, resolving the colitis. He declined the option to resume immunotherapy and transitioned to comfort care (Figure 1). Discussion: Overlapping ICIH and ICIC is rare and may have discordance between symptomatology and lab findings. Early recognition of overlapping ICIH and ICIC, supportive treatment, permanent cessation of the inciting ICI and switching it with alternative immunosuppressive therapy may improve patient outcomes and quality of life.Figure 1.: Panel A - CT chest/abdomen with contrast (coronal view) showing common bile duct dilation of 1.2 cm (yellow calipers) status post cholecystectomy. Panel B. Upper endoscopy showing prominent ampulla with free-flowing bile. Panel C. Histology of percutaneous, ultrasound-guided liver biopsy with H&E staining (10×) shows preserved lobular hepatic architecture with mixed inflammatory infiltrate including lymphocytes, histiocytes, and scattered eosinophils expanding the portal tracts. Table 1. - Immune Checkpoint Inhibitor Associated Hepatitis Grades, adapted from the American Society of Clinical Oncology, 2021 Grade Criteria 1 Asymptomatic (AST or ALT > ULN to 3.0 X ULN and/or total bilirubin > ULN to 1.5 X ULN) 2 Asymptomatic (AST or ALT > 3.0 to ≤ 5 X ULN and/or total bilirubin > 1.5 to ≤ 3 X ULN) 3 AST or ALT 5-20 X ULN and/or total bilirubin 3-10 X ULN, OR symptomatic liver dysfunction; fibrosis by biopsy; compensated cirrhosis; and reactivation of chronic hepatitis 4 AST or ALT > 20 X ULN and/or total bilirubin > 10 X ULN OR decompensated liver function (e.g., ascites, coagulopathy, encephalopathy, and coma) Abbreviations: AST, aspartate transferase; ALT, alanine transaminase; ULN, upper limit of normal.

S1733 Exceedingly Rare Coexistence of Metamorphosis of Tubulovillous Adenoma of the Ampulla to Adenocarcinoma with Small Bowel Gastrointestinal Stromal Tumor - Case Report and Review of the Literature

Introduction: This is a unique case of a patient with 3 tumors, which include one benign tumor, tubulo-villous adenoma of the ampulla of Vater (TVAoA), and 2 extremely rare malignant tumors, adenocarcinoma of the ampulla of Vater arising from TVAoA and gastrointestinal stromal tumor (GIST) involving the jejunum. Based on literature review, this is the first case of ampullary adenocarcinoma coexisting with GIST. Distal duodenal polyps are uncommon and have preponderance to occur in and around the ampulla of Vater. We report a case of a 77-year-old male who was admitted for painless obstructive jaundice with a 40-pound weight loss over a 2-month period, and who was subsequently diagnosed with 3 tumors. Case Description/Methods: A 77-year-old man was admitted for generalized weakness with associated weight loss of 40 pounds in the previous 2 months and was noted to have painless obstructive jaundice. Computed tomography (CT) of the abdomen and pelvis and magnetic resonance cholangiopancreatography were consistent with a polypoid mass at the level of the common bile duct (CBD) and ampulla of Vater with CBD dilatation. The same lesions were visualized by endoscopic retrograde cholangiopancreatography. Histopathology of endoscopic forceps biopsy showed tubulo-villous AoA (TVAoA). Histopathology of the surgical specimen of the resected ampulla showed adenocarcinoma arising from the TVAoA. Abdominal and pelvic CT also showed a coexisting heterogeneously enhancing, lobulated mass in the posterior pelvis originating from the jejunum (Figure). The patient underwent resection of the mass and jejunojejunal anastomosis. The histopathology of the resected mass confirmed it as a high-grade GIST. Discussion: AoA can occur sporadically and in a familial inheritance pattern in the setting of FAPS. We emphasize screening and surveillance colonoscopy when one encounters AoA in upper endoscopy to check for FAPS. AoA is a premalignant lesion, particularly in the setting of FAPS, that carries a high risk of metamorphism to ampullary adenocarcinoma. Final diagnosis should be based on a histopathologic study of the surgically resected ampullary specimen, and not on endoscopic forceps biopsy.This case is unique because he had 3 tumors and rare coexistence, which included one premalignant TVAoA and 2 malignant tumors: ampullary adenocarcinoma arising from the TVAoA and coexisting jejunal GIST.Figure 1.: Figure1A: CT abdomen and pelvis with contrast. Obstructed distal common bile duct due to a 9 mm polypoid intraluminal (pointed yellow arrows) lesion in the distal CBD. Figure1B: CT of the abdomen and pelvis with contrast. Heterogeneously enhanced lobulated mass with punctate calcifications (pointed yellow arrows) in the posterior pelvis originating from the serosal surface of the pelvic small bowel. Figure1C: Endoscopic retrograde cholangiopancreatography (ERCP) showed abnormal papilla with polypoid mass. Sphincterotomy and deep cannulation procedures were performed and confirmed by fluoroscopy. It showed common bile duct dilatation, and there was an abrupt cutoff at the distal aspect. Figure1D: High-power photomicrograph showing high-grade glandular dysplasia (hematoxylin and eosin stain, 200 X original magnification) Figure1E: A broad base ampullary mass with red fogerty cath was advanced from the cystic duct down through the ampulla to the duodenum. Figure1F: Pedunculated GIST arising from the small bowel approximately 150 cm proximal to the ileocaecal valve.

S3467 Primary Duodenal Adenocarcinoma: A Rare Malignancy

Introduction: Primary duodenal adenocarcinoma (PDA) is extremely rare, representing 0.3 – 1% of all gastrointestinal malignancies. It poses a significant challenge to the physicians due to late non-specific symptoms that delays the diagnosis. Surgical resection is the only treatment option although PDA with distant or nodal metastasis have a very poor prognosis. Case Description/Methods: A 33-year-old male patient presented with epigastric abdominal pain, nausea, vomiting, lipase > 2000, elevated LFTs and hyperbilirubinemia, consistent with acute pancreatitis. CT abdomen and pelvis revealed an irregular mass in the second and third portion of the duodenum near ampulla, dilation of pancreatic and common bile duct along with multiple hepatic lesions, consistent with metastatic malignancy. EGD showed non bleeding duodenal ulcer along with enlarged lymph nodes in the peripancreatic region. Biopsy of the ulcer was suggestive of moderately differentiated invasive duodenal adenocarcinoma with background of high-grade dysplasia. Due to metastatic malignancy, patient was started on folinic acid, fluorouracil and oxaliplatin without undergoing surgery. Percutaneous biliary drain was placed with resolution of pancreatitis and hyperbilirubinemia. Patient also completed a course of antibiotics due to pseudomonas bacteremia and sepsis secondary to pancreatic phlegmon that was drained. Pain was management with fentanyl patch and oral opioids. Patient was later discharged home with outpatient follow up. Discussion: This case highlights the importance of primary duodenal adenocarcinoma (PDA) which is a very rare malignancy. Its etiology is unknown, however patients with familial adenomatosis polyposis, Peutz-Jeghers syndrome, Crohn’s and celiac disease are at higher risk. Due to non-specific symptoms including anorexia, postprandial fullness, nausea, vomiting, jaundice and abdominal pain, early diagnosis is a challenge for physicians. PDA is most commonly seen in second part of the duodenum with an incidence of 50 -70%. It can be diagnosed with the help of contrast imaging studies along with EGD and biopsy. Management is usually surgical resection with tumors of the second part of the duodenum, proximal and distal infiltrating tumors requiring pancreaticoduodenectomy to ensure radical resection. Lymphovascular invasion, lymph node metastasis and perineural invasion are features associated with poor prognosis and high mortality. For unresectable tumors, palliative surgery or endoscopic treatment is usually indicated.

S1910 A Rare Metastatic Lesion in the Pancreas Presenting With Biliary Obstruction

Introduction: Pancreatic malignancies can originate from either endocrine or non-endocrine cells of the pancreas. Ductal carcinoma is the most common type of non-endocrine tumor, of which adenocarcinomas constitute the most common pancreatic malignancy. Squamous cell carcinoma (SCC) is the other ductal tumor that is very rare as the pancreas is generally devoid of squamous cells. Primary SCC of the pancreas is thought to arise from the squamous metaplasia of the ductules secondary to chronic inflammatory conditions, however, metastasis remains the most common etiology. We present a patient with history of recurrent poorly differentiated SCC of the cervix complicated by pancreatic head metastasis and biliary obstruction. Case Description/Methods: A 46-year-old female diagnosed with poorly differentiated SCC of the cervix stage IIB, status post multiple rounds of chemotherapy over a period of 4 years, was started on a new medication – Tisotumab. Four months following the initiation of this medication, patient experienced abdominal pain and was noted to have a lipase level of 1160 U/L. She was diagnosed with acute pancreatitis and treated accordingly. Subsequent labs showed continued up trending of her liver chemistry, withalkaline phosphatase of 520 U/L and total bilirubin of 9.7 mg/dl. A CT abdomen performed revealed dilation of both common bile duct (CBD) and pancreatic duct (PD) with subtle hypodense area in the head of pancreas. Endoscopic ultrasound (EUS) was performed which revealed a 3 cm x 2 cm ill-defined hypoechoic and heterogenous mass in the pancreas head (Figure). Fine needle biopsy of the lesion revealed SCC, most likely metastatic from the cervix. ERCP was performed and a 10mm x 8cm fully covered metal CBD stent was placed with normalization of liver enzymes. Palliative immunotherapy with Keytruda is currently being pursued. Discussion: Metastasis to the pancreas is an uncommon clinical condition and accounts for 0.5-5% of all pancreatic malignancies. Because of the rarity, primary sources should always be excluded. Only a handful of reports of uterine and cervical cancer metastasis to pancreas have been reported, most of them being adenocarcinoma. We report a very rare case of SCC cervix metastasizing to the pancreas. Unfortunately, curative surgery is not an option with metastatic disease, and chemoradiation can be used palliatively. The median survival is generally poor with median rates of 4.8% and 1% at 1-yr and 5-yrs, respectively.Figure 1.: A - EUS image showing dilated CBD measuring up to x mm. B – EUS image demonstrating a 3 x 2 cm hypoechoic pancreatic head mass. C– H&E stain showing neoplastic clusters (black arrows) of metastatic SCC.

S3531 A Rare Cause of Obstructive Jaundice: Afferent Limb Syndrome

Introduction: Afferent limb syndrome (ALS) is a rare but potentially life-threatening complication of upper gastrointestinal (GI) surgery and reconstruction causing distal obstruction of the biliopancreatic limb with subsequent accumulation of bile, pancreatic fluid, and other small bowel secretions upstream afferent limb dilation. It is imperative to recognize this complication postoperatively as buildup in the small bowel can result in bowel perforation requiring emergency surgery. We present a patient who developed ALS after upper gastrointestinal reconstruction with esophagojejunostomy for the treatment of gastric adenocarcinoma. Case Description/Methods: An 84 year-old female with a past medical history of gastric adenocarcinoma with total gastrectomy and esophagojejunostomy presented to the emergency department with a subacute history of upper abdominal pain and new-onset jaundice. Initial labs were notable for elevated liver chemistries including alkaline phosphate level of 435 U/L (normal 39-117 U/L), alanine transaminase of 62 U/L (normal 6-45 U/L), and aspartate transaminase of 36 U/L (normal 10-25 U/L). Abdominal ultrasound demonstrated markedly dilated common bile and intrahepatic ducts and gallbladder distention without stones. CT scan of the abdomen confirmed the ultrasound findings, but also identified a dilated duodenum with an abrupt transition point in the proximal jejunum suggestive of ALS shown in Figure A. The patient underwent open laparotomy which demonstrated multiple tumor implants. A large implant at the site of the previous jejunojejunostomy was identified as the cause of afferent limb obstruction. A palliative bypass was performed. The patient had a complicated post-operative course. Ultimately, due to the extensive disease burden and ongoing patient discomfort, the patient and their family decided to pursue hospice care. Discussion: ALS is a post-operative complication of upper GI tract surgery that involves mechanical obstruction of the biliopancreatic limb. Patients often present with jaundice. CT scan is the preferred diagnostic modality. First-line treatment involves surgery to relieve the obstruction with revision of the prior anastomosis. Although rare, this diagnosis should be considered in appropriate patients.Figure 1.: A: CT scan with markedly dilated intrahepatic and extrahepatic biliary ductal dilation, distended gallbladder, and markedly dilated duodenum with abrupt transition point in proximal jejunum.

S2870 Successful Use of EUS-Guided Choledochoduodenostomy With LAMS in a Post-Liver Transplant Patient With Recurrent Choledocholithiasis and Cholangitis

Introduction: Biliary complications, like anastomotic stricture and cholangitis, are seen in 10-15% of orthotopic liver transplants (OLT). OLTs often require multiple endoscopic retrograde cholangiopancreatoscopy (ERCP) for recurrent disease. Endoscopic ultrasound guided choledochoduodenostomy (EUS-CD) has been effective in treatment of malignant distal biliary obstruction after failed ERCP; however, there are limited reports regarding EUS-CD in OLTs. We present a case of successful EUS-CD with lumen apposing metal stents (LAMS) in an OLT with recurrent cholangitis secondary to benign anastomotic stricture refractory to management with ERCP. Case Description/Methods: A 61-year old female with 3 OLTs (1996 and twice in 2008) for autoimmune hepatitis presented with recurrent cholangitis secondary to anastomotic biliary stricture in the setting of duct mismatch with a dilated common hepatic bile duct to 3 cm. She had recurrent choledocholithiasis measuring 3 cm despite prior mechanical and electrohydraulic lithotripsy with cholangioscopy confirmed clearance. As a result, she had undergone a total of 26 prior ERCP treatments (2012-2021). She underwent an EUS-CD with LAMS for definitive treatment. 2-weeks later, an upper endoscope was traversed through the LAMS to perform lithotripsy of remaining choledocholithiasis. At this time, the patient remains free of cholangitis for the past 8 months. (Figure) Discussion: Biliary complications, like anastomotic stricture and recurrent cholangitis, are a common occurrence in OLTs. With use of various ERCP techniques, obstructions can be removed or ameliorated. Timely treatment of cholangitis is imperative as the mortality rate is high (10-30%). With each cholangitis episode and subsequent ERCP, the cumulative procedural risk and mortality increases. EUS-CD has been demonstrated to be effective in treatment for malignant distal biliary obstruction after failed ERCP. Our patient had previously undergone 26 ERCPs and additionally was on Warfarin for pulmonary embolism putting her at very high risk for complications with additional future endoscopic procedures. This represents a case of successful use of EUS-CD with LAMS in a patient post-OLT with a significant distal common bile duct stricture which had been refractory to traditional management via ERCP. Long term studies are indicated to see if this can provide durable benefit.Figure 1.: 1A. MRI imaging demonstrating a large 3 cm choledocholithiasis within the dilated CBD, which formed as a result of bile stasis. 1B. CT coronal view demonstrating successful deployment of LAMS to complete EUS-CD. 1C. Fluoroscopic view of the standard upper scope traversing through the LAMS for definitive lithotripsy and dredging of remaining choledocholithiasis. 1D. Endoscopic view of the final LAMS placement with double pigtail plastic stents.

S1822 Recurrent Pancreatitis Secondary to Common Channel Volvulus Through Petersen’s Space Defect in a Patient With Roux-en-Y Bypass

Introduction: Petersen’s space hernia is an internal hernia that can occur after Roux-en-Y gastrojejunostomy. The intestinal loops herniate through a defect between the retroperitoneum, the transverse mesocolon and the small bowel limbs. We present a case of recurrent pancreatitis in a patient with Roux-En-Y bypass found to have common channel hernia through a Petersen’s space defect. Case Description/Methods: We present the case of a 34-year-old female with a history of Roux-en-Y surgery in 2018 and subsequent recurrent pancreatitis who presented to the emergency department with a chief complaint of severe epigastric and left lower quadrant abdominal pain associated with hematemesis. Patient reported 3 episodes of pancreatitis within 1 year previously. CT abdomen and pelvis showed mildly dilated common bile duct and intrahepatic biliary dilatation with no evidence of pancreatitis. Significant lab work included elevated lipase at 184 U/L. Patient was admitted to the medical service. Gallbladder ultrasound revealed no evidence of cholelithiasis, a prominent CBD of 9 mm and redemonstrated mild intrahepatic biliary dilatation. MRCP revealed a mesenteric swirl in the mid abdomen which was suspicious for an internal hernia in the setting of antecolic Roux-en-Y gastric bypass. It also showed focally dilated intrahepatic with underlying segmental atrophy. General surgery consultation was sought, with eventual plans for diagnostic laparoscopy after ruling out marginal ulcer via EGD. An EGD was performed which did not show evidence of marginal ulcer. Patient then underwent diagnostic laparoscopy which revealed a 360-degree volvulus of the common channel through a Petersen’s space defect; this was carefully reduced, and the Petersen’s space defect was closed. Patient also underwent laparoscopic cholecystectomy. Patient did not have any further episodes of pancreatitis after surgery. Discussion: This case demonstrates recurrent pancreatitis in a patient with a history of Roux-En-Y bypass found to have a common channel volvulus through a Petersen’s space defect. It is our understanding that the volvulus likely caused compression of the pancreaticobiliary system, thus causing recurrent pancreatitis. Reduction of the volvulus and closing of the Petersen’s defect resulted in complete resolution of recurrent pancreatitis in the patient.

S1871 A Case of Ketamine-Induced Cholangiopathy: A Novel Diagnosis Associated With Chronic Recreational Ketamine Use

Introduction: Ketamine, an analgesic commonly used for procedural sedation, has become a popular agent for recreational use among young adults. The diagnosis of ketamine-induced cholangiopathy is uncommon. We report a case of a young adult with clinical and radiological features consistent with cholangiopathy induced by chronic ketamine use. Case Description/Methods: A 19-year-old female with past medical history of peptic ulcer disease presented to emergency department (ED) with one year history of severe epigastric abdominal pain. On further questioning, patient reported chronic recreational ketamine use. Physical exam revealed mild epigastric and RUQ tenderness. Liver function test demonstrated elevated alkaline phosphatase of 174 U/L, AST of 237 U/L and ALT of 224 U/L. All other hematology and chemistry results were within normal limits. RUQ ultrasound showed minimally dilated common bile duct (CBD). An MRCP was obtained, showing mild-to-moderate dilatation of intra-/extra-hepatic bile ducts and dilated cystic duct (CD) without obvious intraductal calculi (Figure A). Endoscopic ultrasonography (EUS) was performed showing dilatation of CBD, minimal dilatation of common hepatic duct, and minimal dilatation of CD, once again without obvious calculi (Figure B). These imaging findings are compatible with ketamine-induced cholangiopathy. After being admitted for 6 days, the patient demonstrated significant improvement in her abdominal pain, with gradually improving liver test values. She was discharged with the recommendation to abstain from ketamine use and outpatient gastroenterology follow-up. Discussion: Chronic exposure to ketamine has been known to cause urologic injury, referred to as ketamine-induced ulcerative cystitis. In comparison to the urologic complications of chronic ketamine use, its effects on the biliary system have been less commonly reported. Existing reports have mostly come from regions of Asia where recreational ketamine use is more prevalent. The nonspecific gastrointestinal symptoms that are typically reported by patients with ketamine-induced cholangiopathy may make the diagnosis more challenging to recognize. Due to increasing recreational ketamine use among young adults in recent years, cases of ketamine-induced cholangiopathy are likely to rise. Therefore, a better understanding of the clinical and radiological features of this condition are needed to allow for prompt recognition of ketamine-induced cholangiopathy.Figure 1.: A. MRCP image showing mild-to-moderate dilatation of the intrahepatic and extrahepatic bile ducts and dilatation of the cystic duct. There are no visible stones or evidence of other etiology for the dilatation. B. EUS image displaying CBD dilatation measuring up to 10.6 mm in the head region, with smooth tapering to the ampulla where it measured 2.7 mm.

S1891 A Diagnostic Dilemma: Primary Sclerosing Cholangitis With High IgG4 vs IgG4-Related Sclerosing Cholangitis

Introduction: Two etiologies of sclerosing cholangitis with overlapping features are Type 2 IgG4-Related Sclerosing Cholangitis (IgG4-SC) and Primary Sclerosing Cholangitis with high IgG4 (PSC). Here, we present a complex case of a young patient with features of both diseases. Case Description/Methods: A 25-year-old Caucasian female with a medical history of diabetes and no previous pancreatic disease was incidentally found to have an AST and ALT in the low 200s, total bilirubin 2.6, and alkaline phosphatase of 1130 concerning for cholestatic obstruction. She was asymptomatic and not jaundiced at the time. Subsequent MRCP revealed a dilated common bile duct. The patient underwent ERCP/EUS demonstrating a common bile duct stricture. A plastic stent was placed, and cells for cytology/FISH analysis were unyielding for malignancy. Repeat ERCP/EUS was performed a few months later for stent exchange. Biopsies to evaluate the indeterminate stricture yielded IgG4+ plasma cells up to 14/HPF. Based on the findings suspicious for IgG4-SC, she started prednisone therapy for one month. Subsequent labs demonstrated mild improvement in alkaline phosphatase to 450, total bilirubin 0.2, and a normal IgG4 level but with persistent elevation of total IgG 1.5 times the upper limit of normal. Repeat ERCP demonstrated resolution of the distal biliary stricture. She never developed abdominal pain, jaundice, weight changes or loss of appetite. Six months later, LFTs began to uptrend and a third ERCP/EUS demonstrated new distal biliary stricture. Biliary biopsies showed dense lymphoplasmacytic infiltrates and fibrosis with an average of 10 IgG4 positive plasma cells/HPF. Liver biopsies showed periductal fibrosis and a fibro-obliterative duct lesion. Given the concern for PSC, colonoscopy was performed with biopsies showing mild crypt distortion, mild eosinophilia, and rare neutrophils in the lamina propria. The patient remained asymptomatic throughout the disease course but had persistent biochemical hepatitis despite being on steroid therapy. A shared provider-patient decision was made to withhold immunosuppressive or biologic therapy. Discussion: In this case, the patient’s epidemiologic, clinical, and histological factors were more consistent with PSC. Conversely, the mild biochemical and stricture steroid-responsiveness were initially more suggestive of IgG4-SC. It is imperative to delineate between the two, as prognosis, treatment-responsiveness, and anticipated comorbidities differ.

S2832 First Trimester Subcapsular Hepatic Hematoma Following Endoscopic Retrograde Cholangiopancreatography

Introduction: Endoscopic retrograde cholangiopancreatography (ERCP) is commonly utilized to treat pancreaticobiliary diseases and is considered safe in pregnancy. We describe a case of ERCP indicated for choledocholithiasis in a newly pregnant patient which resulted in a very rare complication related to guide wire trauma. Case Description/Methods: A 24-year-old female presented to the emergency department with right upper quadrant pain, fever, leukocytosis, and obstructive jaundice. Bloodwork revealed she was 8 weeks pregnant. Imaging studies showed acute cholecystitis and choledocholithiasis with a dilated common bile duct of 1.2 cm. Therapeutic ERCP was performed with minimal use of fluoroscopy to reduce fetal exposure. Double wire technique was utilized and the bile duct was successfully cannulated with a 0.025 mm angled-tipped hydrophilic wire. Sphincterotomy was performed, followed by sphincteroplasty. The bile duct was swept with a 12 mm balloon but only one stone was extracted. To avoid further fetal fluoroscopy exposure, double plastic stents were placed into the common bile duct and a single pigtail plastic stent was placed into the pancreatic duct. The following day, she became hemodynamically unstable. Labs suggested an improved cholestatic pattern and improved leukocytosis post ERCP decompression. Due to worsening hepatocellular injury and hemodynamic instability, a computed tomography angiogram was performed. A 3.9 cm subcapsular hepatic hematoma with capsular retraction and parenchymal distortion of the superior right hepatic lobe was found. Interventional radiology catheter embolization was attempted. Aggressive conservative management with blood transfusions and close monitoring successfully stabilized the patient. The patient ultimately had a spontaneous abortion and returned for an outpatient ERCP with biliary stent removal and stone extraction. Discussion: Although a very rare complication, this case does highlight the possibility of angled-tipped hydrophilic guide wire hepatic trauma and clinically significant bleeding. When strongly indicated, ERCP should be performed in people who are pregnant, but exposure to fluoroscopy should be minimized. Similar cases hypothesize that liver injury is attributable to traumatic damage to the intrahepatic biliary tree and hepatic parenchyma by the ERCP guide wire.Figure 1.: Computed tomography of the abdomen revealed a hypodense subcapsular collection on the right side of the liver. The bleed continues inferiorly and medially. A plastic pancreatic stent and a plastic biliary stent are also visible.

S3439 Lemmel Syndrome Due to Periampullary Diverticular Food Impaction

Introduction: Lemmel Syndrome is a rare cause of mechanical biliary obstruction attributed to periampullary duodenal diverticula (PAD). It was first described in 1934 as obstructive jaundice in the absence of biliary stones or malignancy. The majority of PAD are asymptomatic, however, about 5% have symptomatic disease. We present a symptomatic case. Case Description/Methods: An 80-year-old woman with history of cholecystectomy, coronary artery disease, hypertension, and diabetes was transferred from a free-standing emergency room for acute pancreatitis. She had a one day history of postprandial epigastric pain with radiation to the back. Labs on presentation included lipase above 4000 U/L, BUN 27 mg/dL, AST 316 U/L, ALT 422 U/L, ALP 292 IU/L, total bilirubin 0.6 mg/dL. Abdominal ultrasound revealed 12mm common bile duct (CBD) with intrahepatic ductal dilatation. MRCP showed intra and extrahepatic biliary ductal dilatation with dilated pancreatic duct and a 3.6 cm fluid filled periampullary diverticulum. ERCP showed a large periampullary duodenal diverticulum with food impaction causing obstruction of the ampullary orifice which was removed with forceps. Cholangiogram revealed dilation of pancreatic, common bile, and intrahepatic ducts without any filling defects. Patient improved and was discharged home. (Figure) Discussion: The incidence of duodenal diverticula is approximately 17% with PAD being the most common type. PADs are pseudo-diverticula most commonly found in the second part of the duodenum and they pose a cannulation challenge during ERCP with an increased risk of complications. PAD in the setting of biliary obstruction is known as Lemmel Syndrome. It can cause biliary obstruction by sphincter of Oddi dysfunction, direct obstruction, or via external compression by fluid or material-filled PAD. In our case, there was biliary compression due to a food-filled PAD. Cross sectional imaging is critical for diagnosis, however, ERCP is the gold standard. Several therapeutic modalities including endoscopic extraction of entrapped food or stones, extracorporeal shock wave lithotripsy, and laparoscopic diverticulectomy have been used. Our case required endoscopic extraction of diverticular food debris and adds to the limited published cases to date. Lemmel Syndrome requires a high index of suspicion when a PAD is found in the setting of biliary obstruction.Figure 1.: A. MRCP image showing a large periampullary diverticulum packed with debris. B. ERCP image of food impacted inside periampullary diverticulum. C. MRCP image demonstrating a dilated common bile duct in absence of choledocholithiasis.

S1869 A Case of Biliary Intraepithelial Neoplasia of the Extrahepatic Bile Duct

Introduction: Biliary intraepithelial neoplasia (BilIN) is a relatively new diagnosis that refers to flat or micropapillary precursor lesions of the bile duct which can develop into adenocarcinomas. Herein, we present a case of an extrahepatic biliary intraepithelial neoplasia that was found during endoscopic retrograde cholangiopancreatography (ERCP). Case Description/Methods: 54-year-old male with a history of hypertension and tobacco abuse presented with sharp, right upper quadrant abdominal pain with intermittent nausea and vomiting of one month duration. On admission, he was hemodynamically stable, with normal labs including liver function tests. MRI/MRCP revealed intra- and extra-hepatic duct dilation up to 12 mm with no intraductal filling defect or stricture and a normal gallbladder. (Figure A).The patient underwent an EUS which revealed common bile duct dilation up to 12 mm with a hypoechoic lesion in the distal bile duct, just proximal to the ampulla (Figure B). Given the EUS findings, an ERCP was performed. Cholangiogram revealed diffuse dilation of the biliary tree with no obvious stricture or filling defect (Figure C). The biliary tree was swept, and nothing was found. Due to the suspicious lesion seen on the EUS we performed distal common bile duct brushing and biopsies. Histopathology revealed biliary intraepithelial neoplasia, grade 2 (Figure D). His pain was controlled and was discharged with plans for pancreaticoduodenectomy (Whipple’s) procedure. Discussion: BilIN refers to flat or micropapillary precursor lesions of the bile duct which can develop into adenocarcinomas. They are commonly found in liver samples of chronic biliary and liver diseases such as hepatolithiasis, primary sclerosing cholangitis, choledochal cyst, chronic hepatitis C, and alcoholic cirrhosis. However, they are rarely found in clinical practice since they are not easily accessible, nor do they usually cause bile duct obstruction. The natural course of BillN is not well understood and in 2017, diagnostic criteria were created for lesions found in the intrahepatic duct based on their cellular and structural atypia. Lesions in the extrahepatic duct do occur, however, very rarely. This case is unusual in that the BilIN caused symptoms suggestive of biliary obstruction with a dilated bile duct and because the BillN was found in the extrahepatic duct. The case highlights the importance of considering BilIN in biliary obstruction and perform biopsies to identify the lesions prior to development of malignancy.Figure 1.: (A) MRI T2 flare reveals intra- and extra-hepatic duct dilation up to 12 mm with no intraductal filling defect or stricture. (B) EUS reveals hypoechoic lesion in the distal bile duct, just proximal to the ampulla. (C) ERCP cholangiogram reveals diffuse dilation of the biliary tree with no obvious stricture or filling defect. (D) Hematoxylin and eosin stain reveals dysplastic biliary epithelium (flat architecture; enlarged, hyperchromatic nuclei with nucleoli and some pseudostratification, rare mitotic figures) consistent with BilIN grade 2.

S1731 Fibrosing Pancreatitis Initially Diagnosed as Ductal Adenocarcinoma by Endoscopic Ultrasound of a Pancreatic Mass in a Pediatric Patient

Introduction: Pancreatic cancer is very rare in the pediatric population. Incidence data is scarce, and few case reports have been published. Pancreatic ductal adenocarcinoma (PDA) is the most common subtype in adults, but is rare in children. We report a case of a benign pancreatic head mass in a pediatric patient initially diagnosed as PDA on endoscopic ultrasound (EUS) guided biopsy. Case Description/Methods: A 13-year-old male with past medical history of treated Helicobacter pylori infection 6 months prior was admitted for severe acute intermittent epigastric pain. Labs showed elevated transaminases and gamma-glutamyl transferase. Abdominal ultrasound demonstrated an indeterminate solid mass-like lesion of 3 cm at the pancreatic head, and the common bile duct (CBD) was dilated to 0.9 cm. Magnetic resonance cholangiopancreatography showed a 2.2 cm indeterminate lesion along the pancreatic head region with dilated CBD of 1.4 cm, tapering at the level of the lesion. On hospital day 3, the patient underwent esophagogastroduodenoscopy and EUS. A parenchymal mass of 2.2 cm was visualized in the head of pancreas, and fine needle biopsy was performed. Cytology diagnosis was well differentiated ductal adenocarcinoma. Serum carcinoembryonic antigen, carbohydrate antigen 19-9, and alpha-fetoprotein were all normal. The patient underwent elective Whipple procedure. Surprisingly, no malignancy was identified on the surgical specimen. Instead the findings supported a diagnosis of localized fibrosing pancreatitis with high background of immunoglobulin G4 with interlobular pattern. Patient was discharged home on post-operation day 13. EUS cytology was reviewed at a tertiary cancer center and later reported as acute on chronic inflammation without malignancy (Figure). Discussion: Despite increased use of EUS for diagnosis of pancreatic masses, 5-10% of patients who undergo Whipple procedure for presumed malignancy will have benign pathology: most commonly chronic fibrosing pancreatitis, chronic pancreatitis, or focal active pancreatitis. The false positive rate for diagnosing malignancy using EUS-fine needle aspiration (FNA) of solid pancreatic lesions is less than 1%. However, it may be higher in pediatrics as the prevalence of PDA is much lower in adults. For suspected cases of PDA in pediatric patients, additional review of EUS cytology at an experienced and dedicated cancer institution is advisable before further intervention to prevent the medical and psychosocial ramifications of a false positive cancer diagnosis.Figure 1.: (Left) A parenchymal mass (2.2 x 1.8 cm) in the head of the pancreas by endoscopic ultrasound (EUS) adjacent to the portal confluence, with the common bile duct dilated to 12.8 mm (marked by yellow cross signs). Initial cytopathology from EUS-FNA of pancreatic head mass A. Diff-Quik staining at low magnification, 4x. B. Smear is cellular and well preserved with sheets, clusters and single malignant cells, 10x. C. Cells have crowded nuclei, 20x. D. Malignant cells exhibit loss of polarity, irregular nuclear contours, finely granular chromatin and some with prominent nucleoli, 40x . Based on cytomorphological features, the mass is a well differentiated ductal adenocarcinoma of pancreatic head. Note: The review of this cytopathology by a tertiary cancer institution was inconsistent with malignancy. The glandular cells had mild cytologic atypia, and the acinar cells remained lobular in configuration. Although there was some higher nuclear to cytoplasmic ratio, no absolute nuclear enlargement was noticed.