Avid FDG Uptake Research Articles

Hypermetabolic Axillary Lymphadenopathy After Shingrix Vaccination for Varicella Zoster Virus.

A 67-year-old woman underwent staging 18 F-FDG PET/CT scan for recently diagnosed breast cancer. Her scan showed a highly hypermetabolic right breast mass, with ipsilateral hypermetabolic axillary lymph nodes. The contralateral axillary lymph nodes were also enlarged with avid FDG uptake, alongside focal increased uptake in the left deltoid muscle. Upon investigation, the patient reported receiving the new zoster recombinant adjuvanted varicella zoster vaccine (Shingrix, GlaxoSmithKline) 4 days before the scan. The lymph node uptake could be potential pitfall for cancer staging.

A RARE CASE OF BRONCHOLITHIASIS PRESENTING WITH CHRONIC COUGH AND MEDIASTINAL ABSCESS

TYPE: Case Report TOPIC: Disorders of the Mediastinum INTRODUCTION: Broncholithiasis is a rare condition characterized by the erosion of calcified material into the tracheobronchial tree. We present a case of broncholithiasis complicated by mediastinal abscess. CASE PRESENTATION: A 58-year-old male presented with chronic cough and lithoptysis. Chest PET-CT demonstrated calcified right infrahilar and subcarinal soft tissue with avid FDG uptake. Infectious workup was negative, including histoplasma and mycobacterium testing. Bronchoscopy demonstrated mucosal inflammation around the bronchus intermedius. Endobronchial biopsies and EBUS-TBNA were negative for malignancy. Symptoms persisted despite multiple courses of antibiotics and prednisone. Repeat CT showed evolving mediastinal fluid collection and gas. The patient underwent right lower lobectomy and mediastinal lymphadenectomy which showed broncholithiasis, necrotizing granulomas as well as fibrinous and organizing inflammation. Following surgery, he developed right hydropneumothorax requiring chest tube placement with polymicrobial growth consistent with empyema. He was treated with IV antibiotics with subsequent resolution of his symptoms. DISCUSSION: Broncholithiasis is an exceedingly rare cause of chronic cough. Tuberculous and histoplasma necrotizing granulomatous lymphadenitis are the most common causes. Lithoptysis is an uncommon, but a unique symptom of broncholithiasis. Mediastinal abscess is a rare complication as seen in this case. Diagnosis is established by CT imaging and bronchoscopy plays and important role. Depending on disease severity, management options range from observation to bronchoscopic extraction to surgical resection. Caution is advised when bronchoscopic treatment is considered due to the risk of massive bleeding upon manipulation of broncholiths. CONCLUSIONS: Broncholithiasis is a rare complication of mediastinal granulomatous processes that can present with chronic cough, hemoptysis as well as mediastinal abscess. DISCLOSURE: Nothing to declare.

Acute toxoplasmosis mimicking metastatic lymphadenopathy of sarcoma

Abstract Introduction: Clear cell sarcoma is a rare malignant neoplasm with the potential to metastasize to lymph nodes. We report herein a case of acute toxoplasmosis that mimicked metastatic lymphadenopathy from treated clear cell sarcoma on 18F-fluorodeoxyglucose positron emission tomography/computed tomography. Toxoplasmosis is usually asymptomatic in immunocompetent hosts. Acute acquired toxoplasmosis clinically manifests as lymphadenopathy predominantly involving the cervical nodes. Patient concerns: A 45-year-old woman underwent resection of subcutaneous clear cell sarcoma of the right knee. PET/CT performed four years after surgery revealed multiple sites of lymphadenopathy with avid FDG uptake in the right neck, left axilla, left pulmonary hilum, and right inguinal regions. The patient was afebrile and asymptomatic. Metastases were suspected and excisional biopsy of a left axillary node was performed. Diagnoses: Histopathological examination revealed reactive lymphadenitis, suggesting toxoplasmic infection without evidence of malignancy. Serum levels of toxoplasmic immunoglobulin (Ig)M antibodies were high. Serum IgG antibodies were significantly elevated in six weeks from the PET/CT examination. The patient had a cat at home, which could have represented the source of infection. Interventions: The patient was carefully monitored using regular imaging examinations. Outcomes: FDG accumulations resolved spontaneously on follow-up examination one year later. Conclusion: We report a case in which toxoplasmic lymphadenitis mimicked malignant lymphadenopathy. Lymphadenopathy at a distant site from the primary malignancy with FDG avidity may be due to infectious or inflammatory conditions, creating false-positive results.

1267 Recurrent Mantle Cell Lymphoma to the Gall Bladder: A Peculiar PET CT

INTRODUCTION: Mantle Cell Lymphoma (MCL) is a B-cell non-Hodgkin lymphoma that has a variable course. The initial presentation of MCL is usually nonspecific and varies based on the organ involved. Initial treatment includes a variety of chemotherapeutic options; however, almost all patients will have refractory or recurrent disease due to the rapid development of chemotherapy resistance. In this case report, we present a rare presentation of recurrent mantle cell lymphoma in the gall bladder. CASE DESCRIPTION/METHODS: Our patient is a 61-year-old female with history of mantle cell lymphoma diagnosed in 2008. At that time patient was treated with Rituxan/hyper-CVAD with an excellent response to treatment. Patient had a disease recurrence in 2012 on axillary lymph node biopsy and received 6 cycles of Bendamustine and Rituximab and achieved remission as determine by PET CT. The patient decided against allogeneic hematopoietic stem cell transplant (HCT) and was started on Rituximab maintenance therapy by 2013. Patient had another recurrence on axillary lymph node biopsy in 2017 and was placed on Ibrutinib with no FDG noted on subsequent PET-CTs in 2/2018 and 5/2018. A surveillance PET CT performed in 12/2018 showed intense avid FDG uptake involving the gallbladder (Figure 1). A MRI was performed that showed an enhancing lesion in the dorsal aspect of the descending duodenum measuring 18 mm. Upper endoscopy revealed a prominent fold with biopsies taken with no histopathologic abnormality. The patient was subsequently taken for uncomplicated cholecystectomy with one lymph node associated and sent for pathology. Pathology results showed the cystic duct lymph node and gallbladder wall involved by MCL with 40 mitoses per 15HPF and Ki-67 proliferative index of 34% (Figures 2 and 3). This suggested a more aggressive MCL. The patient was started on Revlimid and Rituximab, and will be awaiting clinical trial eligibility at a nearby facility. DISCUSSION: MCL typically follows an aggressive clinical course with high risk of recurrence regardless of chemotherapeutic regimen. One previous case with MCL to the gallbladder was found incidentally as a lymphomatous polyp. An additional case presented with intussception with a mass noted during surgical repair. Overall, there have been approximately 66 cases of B-cell lymphoma noted to the gallbladder, and two prior cases as above of MCL. Our case represents a rare presentation of relapsed MCL to the gall bladder and the wide possibility of metastasis associated with recurrent MCL.

Pancreatic Retroperitoneal Fibrosis Masquerading as a Pancreatic Mass: A Diagnostic Quandary

Retroperitoneal fibrosis (RPF) is a cryptic condition affecting 0.1 per 100,000 patients per year. The pathophysiologic etiology is believed to be autoimmune in nature, resulting in fibrotic tissue deposition within multiple organs. This case highlights an unusual primary pancreatic manifestation of an already exceedingly rare disease. The patient is a 45 year-old male with no significant past medical history who presented with painless jaundice. Computerized tomography revealed a 3 cm pancreatic-head mass encasing the vasculature and ductal system. An endoscopic ultrasound with fine-needle-biopsies (EUS-FNB) of the mass and endoscopic retrograde cholangiopancreatography (ERCP) were performed. The EUS characterized the lesion as a 34 x 28 mm ill-defined heterogeneous mass with multiple collateral blood vessel in the pancreas, suggestive of underlying portal hypertension, correlating with an endoscopic finding of esophageal varices. On ERCP, the common bile duct was dilated to 14mm with a shelf-like distal stricture, treated with a 10 French, 5cm plastic biliary stent. Initial fine needle biopsy results, while inconclusive, could not rule out malignancy or autoimmune pancreatitis. Repeat EUS-FNB with 7 needle passes again returned with non-malignant findings. He subsequently underwent laparoscopic biopsy of the pancreatic mass which revealed sclerosing collagenous fibrosis, displaying lymphoplasmacytic inflammation, suggestive of RPF. Infectious and malignant etiologies for RPF were excluded. He was started on steroids with symptomatic improvement and mass stabilization on subsequent imaging. Through extensive review of the literature, RPF encasing the pancreas without ureteral or periaortic involvement has scarcely been documented. In this case, the mass effect of the fibrosis resulted in biliary obstruction and pre-sinusoidal portal hypertension, and highlights the difficulty in diagnosing an exceedingly rare condition masquerading as pancreatic malignancy. This patient had a protracted course involving multiple sub-specialties, numerous endoscopic procedures, and ultimately a diagnostic surgery. The seemingly elusive diagnosis of RPF conclusively requires histologic certainty prior to treatment. When finally diagnosed, steroids are the mainstay of therapy for RPF.1424_A.tif Figure 1: Dense fibrosis with keloid-type collagen fibers1424_B.tif Figure 2: PET scan showing avid FDG uptake at pancreatic lesion1424_C.tif Figure 3: No Caption available.

A small pancreatic hamartoma with an obstruction of the main pancreatic duct and avid FDG uptake mimicking a malignant pancreatic tumor: a systematic case review

BackgroundPancreatic hamartomas are extremely rare and may be misdiagnosed as malignant tumors. We report herein a case of a small, solid-type pancreatic hamartoma.Case presentationA 72-year-old female was incidentally detected pancreatic lesion by ultrasonography. Computed tomography and magnetic resonance imaging revealed a 2.0-cm solid lesion. The main pancreatic duct (MPD) was obstructed by the lesion in the head of the pancreas, and the upstream MPD was dilated. 18F-fluorodeoxyglucose (FDG) accumulated avidly in the lesion and increased in FDG intensity from the early to the delayed images. The histopathological studies confirmed the diagnosis of pancreatic hamartoma. Immunohistochemically, the cell membrane of the accessory glands and ducts showed homogeneous expression of glucose transporter type I and hexokinase II.ConclusionPancreatic hamartomas causing dilatation of the MPD are extremely rare, and this appears to be the first case of a hamartoma to take up FDG avidly. It was a rare occurrence and should be noted that pancreatic hamartomas can cause an obstruction of the MPD and show avid FDG uptake, thereby mimicking malignant pancreatic tumors.

Duodenal Schwannoma: An Incidental Finding on PET Scan

Introduction: Gastrointestinal schwannomas (GS) are benign nerve sheath tumors arising from Auerbach's plexus. They are rare, accounting for 0.4-1% of all submucosal tumors. GS are most common in the stomach followed by small bowel, then colon and rectum. They may be associated with neurofibromatosis or present as isolated lesions. We present an incidental finding of duodenal schwannoma (DS). Case report: A 58 year old male with history of HTN presented as an outpatient for evaluation of an FDG-avid incidental duodenal mass discovered on PET scan. He was initially found to have nontender cervical lymphadenopathy on routine dental exam. He was otherwise asymptomatic and physical exam was unremarkable. He had no significant past surgical, family, or social history. A lymph node biopsy revealed poorly differentiated squamous cell carcinoma (SCC) of unclear origin. He then underwent PET scan, which identified an oral and duodenal lesion. Primary site of cancer was later confirmed as oropharyngeal SCC, for which he underwent modified radical neck dissection and adjuvant chemoradiation. The duodenal lesion was further evaluated with EGD/EUS with FNA. Endoscopically, an 18x12 mm pedunculated, subepithelial lesion with a long, broad-based stalk was seen in the second portion of the duodenum. Sonographically, it appeared mostly hypoechoic with internal hyperechoic, non-shadowing regions. The exact wall layer of origin could not be delineated. FNA revealed a spindle and epithelioid cell neoplasm, which stained positive for S-100 and SOX10, but negative for CD117, DOG-1 and desmin, supporting the diagnosis of DS. Laparoscopic-assisted, minimally-invasive transduodenal resection is currently scheduled.Figure: Endoscopic view of 18x12mm pedunculated duodenal lesion.Discussion: GS is a mesenchymal tumor of the GI tract. Endoscopic and radiologic exams can identify submucosal lesions but cannot differentiate between the types of mesencyhmal tumors. The diagnosis is made histologically, with immunohistochemical staining for S-100 indicating GS. Although benign, schwannomas can demonstrate avid FDG uptake on PET imaging, and may be mistaken for malignant lesions.GS are typically asymptomatic but can present with nonspecific symptoms. Surgical excision or endoscopic submucosal dissection is recommended for large tumors to avoid complications, such as bleeding or bowel obstruction. Endoscopic surveillance is an option for smaller tumors with asymptomatic presentation due to the benign nature of GS.Figure: Sonographic image of the duodenal lesion taken during EUS.Figure: Fine needle aspiration of subepithelial duodenal lesion showing spindle and epithelioid cell neoplasm, favoring schwannoma (A). Tumor cells positive for schwannoma markers S100 (B) and SOX10 (C).

A Case of 1:1 Correlation Between PET/CT Scan and Endoscopic Findings of Diverticular Disease

Diverticulosis is the most common lesion found on routine colonoscopy and its complications impose a significant burden on US healthcare.It effects 70% of those 80y or older in the US and its incidence is expected to increase with the growing aging population.While diverticular disease may be identified on CT scan, colonoscopy is used to define extent of disease.In cases of brisk diverticular bleeding, nuclear medicine bleeding scans can aid in localizing bleeding source for further intervention, such as angiographic embolization or segmental colonic resection.We present an incidental case of subclinical diverticulitis found on PET/CT scan which was confirmed by endoscopic evaluation. A 55-year old African American male presented to the ED with dyspnea and right upper extremity swelling.CXR and CT demonstrated a pulmonary mass and pathology confirmed stage IIb non-small cell lung cancer. He underwent chemotherapeutic treatment and follow-up PET/CT scan was advised. In addition to confirming the presence lung malignancy, PET/CT scan revealed 3cm of intensely avid FDG uptake in the descending colon, concerning for diverticulitis v. neoplasm.The patient denied bleeding symptoms, weight loss, abdominal pain, change in bowel habits, previous colonoscopy or family history of colon cancer.Outpatient colonoscopy identified scattered diverticular disease in the descending colon, correlating exactly with the location of increased FDG activity on PET/CT scan. One month later, repeat PET/CT scan was performed for surveillance.The two foci of intense short segment activity in the descending colon remained unchanged in intense activity. The lesions demonstrated a perfect 1:1 correlation with the diverticular disease found on colonoscopy. We report the first case of 1:1 correlation between PET/CT and endoscopic findings of diverticular disease. The utility of PET/CT has been well described in the detection of malignant lesions, but our case demonstrates the ability of PET/CT to recognize non-cancerous inflammatory conditions. As PET/CT is twice as costly with radiation exposure comparable to CT, this modality should not be considered as a screening tool.PET/CT may have a role in select cases of pan-colonic diverticulosis to identify areas of severe inflammation amenable to segmental resection instead of total abdominal colectomy.Further studies should investigate whether this functional molecular imaging test may be implemented in this manner.

P1.03-076 Nodal Staging of Patients with Pulmonary Malignancies - The Predictive Value of Different Patterns of Mediastinal 18FDG-PET Activity

In patients with pulmonary malignancies, 18FDG uptake in mediastinal nodes is a sensitive but non-specific indicator of metastatic disease. The pattern of tracer uptake may improve the predictability of such findings. To retrospectively i) compare 18FDG-PET scans and EBUS findings in patients with documented pulmonary malignancies; and, ii) compare the pattern of 18FDG uptake in mediastinal nodes in patients with / without documented mediastinal node metastases. 62 patients with documented pulmonary malignancies underwent 18FDG-PET scintigraphy followed by EBUS within the ensuing 3 weeks. One-two nodes were assessed in each patient, determined by 18FDG-PET findings and accessibility of the FDG-positive nodes. The mediastinal nodal status from each procedure was compared. EBUS resulted in mediastinal nodal status downgrading in 25 (40%) patients. No upgrading was noted. Downgrading most likely occurred when there several non-enlarged lymph nodes of similar 18FDG-avidity distributed randomly and bilaterally in the mediastinum, often with bilateral hilar uptake (17 of 25 patients). Further, only 2 of 19 patients exhibiting such a pattern of mediastinal tracer distribution were found to have lymph node metastases (10%), and both had metastatic disease elsewhere on the PET scan. 21 of 23 patients with positive EBUS findings demonstrated discrete 18FDG-avid lymph nodes ipsilaterally, with minimal-to-no 18FDG-avid nodes contralaterally. EBUS findings in 14 (23%) patients were inconclusive, despite multiple sampling. Enlarged, rounded lymph nodes with avid FDG uptake (SUV>4) were also more likely to harbor metastatic disease. Conversely, a Hounsfield unit of >55 was associated with benign disease. The pattern of mediastinal 18FDG uptake was highly predictive of metastatic disease, and may circumvent the need for EBUS evaluation. Prospective analysis of these parameters will be undertaken.

Recurrent Primary CNS Lymphoma Presenting with Central Neurogenic Hyperventilation

Background: Tumor-induced Central Neurogenic Hyperventilation (CNH) is exceedingly rare, about half resulting from Primary CNS Lymphoma (PCNSL) despite their rarity. Results: We present a 75 year-old, immunocompetent woman with recurrent PCNSL leading to CNH. She was initially diagnosed with PCNSL via biopsy of the single enhancing left caudate focus among diffuse, nonenhancing CNS infiltrative disease without diffusion restriction or CSF or intraocular dissemination. She received 5 cycles of biweekly rituximab and methotrexate, initially dosed at 3.5 gm/m2 with procarbazine and vincristine, then dosed at 8 gm/m2 with monthly temozolomide 150 mg/m2. Repeat brain MRI revealed no residual enhancement with confluent subcortical nonenhancing signal without brainstem involvement suggesting methotrexate-related leukodystrophy. Two weeks after cytarabine consolidation, she presented with intractable emesis without gastrointestinal cause. A week later, she developed marked tachypnea without cardiopulmonary etiology. Blood glasses revealed respiratory alkalosis (maximal pH=7.67, respiration=27, pO2=241; minimum pCO2=10). She remained otherwise neurologically intact. For suspicion of CNH, she was intubated and brain MRI revealed progressive nonenhancing disease without restricted diffusion extending periventricularly from dorsal midbrain to vermis. CSF profile revealed normal protein (40 mg/dL), RBC 97/µL, WBC 3/µL (88% lymphocytes) with negative bacterial cultures, toxoplasma IgG and HSV, JC, CMV, EBV and JC PCRs. Flow cytometry and cytology revealed no lymphoma cells. Brain and body PET revealed avid FDG-uptake in the new periaqueductal nonenhancing tumor, confirming lymphoma recurrence; no extracranial disease was evident. Her CNH resolved though remission was only brief following posterior fossa radiation (30Gy, 17fx), dexamethasone 40 mg/day, and off-label nivolumab 3 mg/kg q 2 weeks. Repeat brain MRI revealed diffuse cerebral nonenhancing disease progression at 4 months after recurrence. She died shortly after transfer to hospice. Conclusion: This represents the first recurrent PCNSL leading to CNH, which was a presenting symptom in all prior PCNSL cases reported and lead to death in the majority.

Histogram analysis for characterization of indeterminate adrenal nodules on noncontrast CT.

To determine the effectiveness of the CT histogram method to characterize indeterminate adrenal nodules above 10 Hounsfield units (HU) on noncontrast CT. Retrospective review of clinical CT data from January 2005 through 2008 identified 194 indeterminate adrenal nodules (>10 HU on noncontrast CT) in 175 patients. 20 nodules in 18 patients were excluded due to large standard deviation (SD > 30) of HU values. Of the remaining 174 nodules, 131 were classified as benign lipid-poor nodules based on size stability for ≥1 year (104), in- and opposed-phase MRI (17), adrenal washout CT (3), or biopsy (7). 43 were classified as malignant by size increase over a short time (30), avid FDG uptake on PET/CT (15), or biopsy (5). Histogram analysis was performed by drawing a circular region of interest on all adrenal nodules. Mean attenuation, total number of pixels, number of negative pixels, and percentage of negative pixels were recorded for each nodule. At the threshold value of >10% negative pixels, 59/131 benign nodules were correctly characterized, but 1/43 malignant nodules was falsely characterized as benign (sensitivity 45%, specificity 98%, positive predictive value 98%). With a slightly higher threshold value of >15% negative pixels, there were no false benign judgments. 36 nodules had more than 15% negative pixels, all of which were benign (sensitivity 27%, specificity 100%, positive predictive value 100%). In the subgroup of benign nodules measuring 11-20 HU, 80% and 54% were identified with threshold values of >10% and >15% negative pixels, respectively. The CT histogram method with a threshold value of >10% negative pixels can identify many benign adrenal nodules with attenuation values >10 HU on unenhanced CT with extremely high specificity. A threshold of >15% negative pixels can achieve 100% specificity. This method is highly robust provided very "noisy" CT examinations (SD > 30) are eliminated.

18F-FDG PET/CT Imaging of Malignant Hepatic Solitary Fibrous Tumor

Solitary fibrous tumor of the liver was rarely documented. F-FDG PET/CT imaging of malignant hepatic solitary fibrous tumor in a 49-year-old male patient was reported. The multifocal hepatic lesions demonstrated avid FDG uptake. FDG PET/CT might be potentially useful in the differentiation of benign and malignant solitary fibrous tumor.

Hepatic Tuberculosis Mimics Metastasis Revealed by 18F-FDG PET/CT

Extrapulmonary tuberculosis can affect almost any organ in the body. Here, we report a rare case of primary hepatic tuberculosis presented as multiple hepatic lesions and enlarged lymph nodes in the retroperitoneum and porta hepatis. PET/CT imaging showed avid FDG uptake by these lesions but did not find any definite primary malignancy. Finally, a diagnosis of primary hepatic tuberculosis was made with histopathologic examination.

Leukemic Infiltration of Peripheral Nerve: Case Series and Review of the Literature (P06.133)

Objective: To review the clinical, laboratory, electrophysiologic, radiologic and pathologic characteristics of leukemic infiltration of peripheral nerve. Background Leukemic infiltration of peripheral nerve is rare. Reported cases have occurred solely in patients with known systemic disease. Design/Methods: Mayo Clinic cases of leukemic infiltration of peripheral nerve identified between January, 2004 and October, 2011 were reviewed. Results: Five patients were identified. All were men with median age of 68 yrs (range 46-72) at time of symptom onset. Three patients had acute myeloid leukemia (AML) and 2 had chronic lymphocytic leukemia (CLL). In 3 patients the diagnosis of leukemia preceded neurological symptoms by 3-25 months. Two patients presented with peripheral nerve involvement and were found to have positive CSF cytology confirming the diagnosis of AML. All patients had painful, progressive motor and sensory deficits. Clinical patterns were mononeuropathy (1), multiple mononeuropathies (1), and plexopathy (3). Electrophysiological examination in 3/4 patients demonstrated a chronic axonal process and 1/4 demonstrated both axonal and demyelinating features. MRI detected mass lesions in 4/5 cases with PET imaging demonstrating avid FDG uptake. Three patients underwent peripheral nerve biopsy, 2 of which were diagnostic of leukemic infiltration. All patients received systemic chemotherapy (three with additional intrathecal chemotherapy) and 3 received radiation therapy. Patients experienced improvement in pain and partial improvement of neurological deficits. Four patients had disease relapse, 4 systemic and 1 also in peripheral nerve. Conclusions: Leukemic infiltration of peripheral nerve is rare. Patients may present with a progressive, painful mononeuropathy or plexopathy. CSF cytology can be diagnostic of leukemia in the absence of systemic involvement. MRI and PET imaging are useful in suggesting a hypermetabolic mass, raising suspicion of neoplasm. Nerve biopsy aids in confirming leukemic infiltration. Treatment with chemotherapy and/or radiation is recommended, but most patients ultimately experience disease relapse. Disclosure: Dr. Reddy has nothing to disclose. Dr. Mauermann has nothing to disclose. Dr. Begna has nothing to disclose. Dr. Ringler has nothing to disclose. Dr. Jerath has nothing to disclose. Dr. Amrami has nothing to disclose. Dr. Spinner has nothing to disclose.

Lymphomatoid Granulomatosis: CT and FDG-PET Findings

ObjectiveLymphomatoid granulomatosis (LG) is a rare, aggressive extranodal Epstein-Barr virus (EBV)-positive B-cell lymphoproliferative disease. The purpose of our study was to analyze the CT and fluorodeoxyglucose positron emission tomography (FDG-PET) findings of pulmonary LG.Materials and MethodsBetween 2000 and 2009, four patients with pathologically proven pulmonary LG and chest CT were identified. Two of these patients also had FDG-PET. Imaging features of LG on CT and PET were reviewed.ResultsPulmonary nodules or masses with peribronchovascular, subpleural, and lower lung zonal preponderance were present in all patients. Central low attenuation (4 of 4 patients), ground-glass halo (3 of 4 patients), and peripheral enhancement (4 of 4 patients) were observed in these nodules and masses. An air-bronchogram and cavitation were seen in three of four patients. FDG-PET scans demonstrated avid FDG uptake in the pulmonary nodules and masses.ConclusionPulmonary LG presents with nodules and masses with a lymphatic distribution, as would be expected for a lymphoproliferative disease. However, central low attenuation, ground-glass halo and peripheral enhancement of the nodules/masses are likely related to the angioinvasive nature of this disease. Peripheral enhancement and ground-glass halo, in particular, are valuable characteristic not previously reported that can help radiologists suggest the diagnosis of pulmonary LG.

Positron emission tomography may underestimate the extent of thoracic disease in lung cancer patients☆

Although widely utilised in the staging of lung cancer various studies have questioned whether the accuracy of this staging modality is sufficient to replace conventional invasive staging techniques. We have therefore reviewed our experience in order to assess the accuracy of PET CT as an intrathoracic staging tool for non-small cell lung cancer (NSCLC). Two hundred patients referred for surgery between June 2006 and January 2008 underwent PET CT followed by staging mediastinoscopy and, if appropriate, resection. Results of scans and histopathology were correlated and analysed. Overall, PET CT correctly staged 99 out of 200 patients (49.5%), under-staged 59 (29.5%), and over-staged 42 (21%). Superior mediastinal nodes were incorrectly staged by PET CT in 35 (19%) of 186 patients undergoing mediastinoscopy: in 15 (8%) mediastinoscopy revealed metastatic disease not detected on PET CT and 20 (11%) had negative histology despite a positive scan. Five (2.5%) resections were benign despite avid FDG uptake, and 6 (3%) were malignant despite a negative scan. PET CT had false positive result of 6.5%, 5.5%, 4.5% and 3.5%, respectively for hilar, station 2, 7 and 5 node groups. The false negative result was 12.5%, 10.5% and 8%, respectively for hilar, intrapulmonary and station 4 nodes. Twelve (6%) of patients were under-staged regarding chest wall and mediastinal invasion, and 10 (5%) patients had metastatic nodules in the lung (T4) not detected by PET CT. Stage I or II disease was identified by PET CT in 141 patients of whom 26 (18.4%) had IIIa or higher stage disease. The false positive and negative predictive values for PET CT with respect to N2 or greater status were 17.2% (11.8-24.2) and 48.6% (32.2-65.3), respectively. Our experience would suggest that PET CT alone is not sufficiently accurate to replace mediastinoscopy and other conventional biopsy techniques in the evaluation of NSCLC cases. It may better be viewed as a valuable additional tool with which to inform decision making and to screen for disseminated disease.

18F-FDG PET/CT findings of sinonasal inverted papilloma with or without coexistent malignancy: comparison with MR imaging findings in eight patients

Sinonasal inverted papilloma (IP) is known for high rate of associated malignancy. The purpose of this study was to identify (18)F-FDG PET/CT findings of sinonasal IPs. We also tried to compare the PET/CT findings with the MR imaging findings. We retrospectively reviewed PET/CT and MR images of eight patients with sinonasal IP with (n = 6) or without (n = 2) coexistent squamous cell carcinoma (SCC). Particular attention was paid to correlate the PET/CT findings with the MR imaging findings in terms of area distribution of standard uptake values (SUVs) and a convoluted cerebriform pattern (CCP). In two benign IPs, the maximum SUVs measured 8.2 and 7.8, respectively (mean, 8.0). In both tumors, MR images demonstrated a diffuse CCP. In six IPs with coexistent SCC, the maximum SUVs ranged from 13.3 to 31.9 (mean +/- SD, 20.2 +/- 6.6). In these tumors, MR images demonstrated a diffuse CCP in two, a partial CCP in three, and no CCP in one. A wide discrepancy was noted between MR imaging and PET/CT in terms of area distribution of a CCP and SUVs. In sinonasal lesions with MR imaging features of IP, (18)F-FDG PET/CT demonstrating avid FDG uptake does not necessarily imply the presence of coexistent malignancy. In our small series, although IPs containing foci of SCC had consistently higher SUVs than IPs without SCC, the limited literature on this subject suggests that PET cannot be used reliably to make the distinction.

Fluorodeoxyglucose positron emission tomography (FDG-PET) and PET/computed tomography imaging characteristics of thyroid lymphoma and their potential clinical utility

A relative paucity of data exists in the literature with regard to the utility of fluorodeoxyglucose positron emission tomography (FDG-PET) imaging in the clinical management of patients with primary lymphoma of the thyroid gland (PTL). To explore the FDG-PET imaging characteristics and their potential role in PTL, and to compare the results with anatomical imaging modalities. Patients with thyroid lymphoma who had undergone whole-body FDG-PET or PET/computed tomography (CT) during their course of the disease were identified by examination of case records. PET scans were reevaluated, and maximum standardized uptake value (SUV(max)) was calculated and used as the semiquantitative measure of FDG uptake for this analysis. CT and/or magnetic resonance imaging (MRI) studies carried out within 1 week of FDG-PET scan and without any therapeutic intervention between the two studies were considered for the purpose of comparison. A total of six patients with 20 studies (14 FDG-PET and six PET/CT examinations) were identified following the criteria. All patients were female (age 16-83 years). Among these, five were proven to have PTL. Two patients had localized PTL (stage IE), two patients had associated regional nodal involvement (IIE), and one patient had associated nodal involvement on both sides of the diaphragm (IIIE) at presentation. Except for one patient with follicular B-cell lymphoma, all others were diffuse large-B-cell lymphoma (DLBCL) subtype. Avid FDG uptake was observed in both cases of untreated PTL, with SUV(max) of 23 and 7.6, respectively. One patient showed focal FDG uptake (SUV(max) 6.7) in the thyroid in the setting of a responding abdominal non-Hodgkin lymphoma (NHL) and was subsequently proven as adenomatous nodule with Hurthle cell changes. Following successful therapy, SUV(max) declined consistently with improvement in disease status. In one patient, complete response was noted earlier by FDG-PET compared to CT. Disease recurrence was detected earlier by FDG-PET compared to CT in two patients with increased FDG activity in both thyroid lobes without any corresponding CT abnormality. FDG-PET is a useful and sensitive modality for assessing disease activity in thyroid lymphoma. Its ability to detect disease recurrence was found to be superior compared to CT in two patients.

Avid FDG uptake in a rapidly enlarging common carotid artery mycotic aneurysm, mimicking lymphadenopathy

We present a case of mycotic pseudoaneurysm of the right common carotid artery, which demonstrated avid FDG uptake mimicking lymphomatous involvement on a non-contrast FDG-PET/CT scan. Within 6 days of initial presentation, the pseudoaneurysm enlarged rapidly and required emergent surgical repair. To the best of our knowledge, this is the first reported case both of a PET-positive non-aortic aneurysm and a rapidly enlarging common carotid artery pseudoaneurysm. This case highlights the importance of contrast administration with PET/CT and the heralding nature of FDG uptake in an aneurysm wall for impending aneurysm rupture.

Avid FDG Uptake in the Right Ventricle Coupled with Enhanced Intercostal Muscle Hypermetabolism in Pneumoconiosis

Avid FDG Uptake in the Right Ventricle Coupled with Enhanced Intercostal Muscle Hypermetabolism in Pneumoconiosis