Anal Pain Research Articles

Physiotherapy management of anorectal dysfunction

Anal incontinence and defecatory difficulties are common and have a considerable impact on quality of life and health cost. Conservative management should be the first line management of anorectal dysfunction because there is minimal risk and a high rate of success with completion of therapy. This article aims to describe the principles of the physiotherapy assessment and the diagnostic process and to summarise published literature focusing on level 1 evidence of the physiotherapy strategies utilised as first-line conservative management of the following anorectal disorders: anal incontinence, defecatory difficulties and functional anorectal pain.

Mpox: What Practicing Gastroenterologists Need to Know

Mpox: What Practicing Gastroenterologists Need to Know

Monkeypox Manifesting as Rectal Pain and Constipation.

Monkeypox Manifesting as Rectal Pain and Constipation.

CASE STUDY OF A PARAVAGINAL HAEMATOMA FOLLOWING VAGINAL DELIVERY

We present the case of a primigravida who had an induced delivery for mild IUGR at 38+6weeks. She had a normal vaginal delivery with right mediolateral episiotomy and minimal vaginal bleeding. She complained of increasing rectal pain in the postpartum period. Vaginal examination revealed a large left sided vaginal haematoma with intact episiotomy wound site.The haematoma was evacuated ,wound exploration done and sutured in layers. Vaginal packing was done. Postoperatively she again complained of rectal pain. Urgent CT scan conrmed nding of a large left pararrectal haematoma with possibility of small left broad ligament extension. She was managed conservatively with vaginal and rectal packing, analgesics,intravenous antibiotics and 3units of packed red cell transfusion. Follow up ultrasound showed reduction in the size of the haematoma and eventual resolution. This case supports the conservative management of even large paravaginal haematomas, when surgical evacuation is technically difcult as long as the patient is clinically stable.

S74 IMHMV: A Rare IBD Mimicker Successfully Treated With Hyperbaric Oxygen Therapy

Background: Idiopathic myointimal hyperplasia of the mesenteric veins (IMHMV) is a rare cause of chronic intestinal ischemia. It is believed to be related to nonthrombotic occlusion of the small to medium sized mesenteric veins due to intimal smooth muscle proliferation. The etiology, pathophysiology and diagnostic criteria are poorly understood and often results in delayed diagnosis. IMHMV is a mimicker of inflammatory bowel disease (IBD) with symptoms including abdominal pain, bloody diarrhea, and weight loss as well as endoscopic evaluation shows ulcerations, edema, and friability. Surgical resection is usually curative. Case presentation: A 50-year-old man with history of kidney transplant on immunosuppressive medications, presented with 2 months’ history of increased urgency, tenesmus and severe rectal pain. Workup showed inflammatory changes in the rectosigmoid colon on CT abdomen-pelvis. Colonoscopy demonstrated a segmental area in the sigmoid colon with severely ulcerated mucosa. He was diagnosed with IMHMV and treated with off-label hyperbaric oxygen therapy (HBOT) with complete resolution of his symptoms and colonic ischemia. Conclusion: IMHMV is a rare mimicker of IBD that requires surgical resection. However, this is the first case in the literature that showed successful treatment of IMHMV with HBOT.

Characteristics and clinical manifestations of monkeypox among people with and without HIV in the United States: a retrospective cohort.

To compare characteristics and clinical manifestations of monkeypox (MPX) between people with and without HIV in the United States. Retrospective cohort study using TriNetX, a federated research network. Patients 18 years and older with MPX were identified based on the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) diagnosis code B04 and divided into two groups: people with HIV (PWH) and people without HIV. Differences in baseline characteristics, clinical manifestations, and all-cause healthcare utilization were examined between groups. Outcomes were reported before and after propensity score matching. Of 322 cases of MPX included, 29% ( n = 93) were PWH. Baseline characteristics were similar, but PWH were more likely to identify as Black or African American persons (24% vs. 11%, P = 0.0303) or as Hispanic or Latino persons (24% vs. 11%, P = 0.0345) and more likely to report lifestyle factors affecting health status. Rash and rectal pain were more common in PWH (25% vs. 11%, P < 0.01, and 25% vs. 10%, P < 0.001, respectively). In addition, PWH had higher rates of anal or rectal abscesses (11% vs. 0%, P < 0.0001), phimosis (11% vs. 0%, P < 0.0001), and pneumonia (11% vs. 0%, P < 0.0001). More PWH required urgent care visits (53% vs. 29%, P < 0.0001) and hospitalizations (11% vs. 4%, P = 0.0314), but not emergency department visits (42% vs. 58%, P = 0.0085). PWH had higher rates of clinical manifestations and required greater utilization of healthcare resources for any reason compared with those without HIV.

Successful Use of Granulocyte Transfusion Therapy As a Bridge to Hematopoietic Stem Cell Transplant in a Child with Aplastic Anemia and Refractory Perirectal Abscess

Background: Idiopathic aplastic anemia (IAA) is a rare, life-threatening acquired form of bone marrow failure characterized by multilineage cytopenias and hypocellular bone marrow. Profound neutropenia associated with very severe aplastic anemia (vsAA) is an important risk factor for development of life-threatening fungal and bacterial infections. Perirectal cellulitis and perianal abscess are one such infection and are associated with high rates of morbidity. The ability to eradicate infections in IAA is limited by the lack of imminent neutrophil recovery prior to treatment with either immune suppressive therapy (IST) or hematopoietic stem cell transplant (HSCT). We describe the successful use of granulocyte transfusion to treat antibiotic refractory proctitis with perianal abscess in a profoundly neutropenic child with vsAA. Case: A 7yoF presented with fever and pancytopenia in the setting of Human Metapneumovirus and Parainfluenza. Bone marrow biopsy showed hypocellularity (60-70%) with granulocytic and megakaryocytic hypoplasia, favoring viral suppression. Ultimately, she progressed to transfusion dependence. Repeat bone marrow aspirate and biopsy ultimately revealed bone marrow aplasia, DEB chromosomes, telomere lengths, and PNH clones were negative, confirming the diagnosis of vsAA. She was subsequently admitted for febrile neutropenia (F&N) and was found to have mild respiratory COVID-19, but began to complain of rectal pain that was initially attributed to her history of constipation. She defervesced on IV antibiotics (abx) and was discharged home with negative cultures. Within a week she represented with hematochezia and F&N and was found to have proctitis with perianal fistula on MRI (figure 1); GI PCR panel was + Enteroaggregative E. coli, no resistant organisms were identified. She clinically improved and discharged on IV piperacillin-tazobactam (pip-tazo). Despite 2 weeks of IV abx, she developed new fever and imaging confirmed persistent proctitis with peri-rectal abscess. As she had limited response to abx alone we trialed a short course of granulocytes with improvement in anorectal inflammation by CT. She was discharged with a plan to continue IV pip-tazo until achieving radiographic cure; however, interval imaging after an additional 2 weeks of abx showed rebound of her proctitis and she was again admitted with F&N and rising inflammatory markers. Her failure to eradicate her peri-rectal infection despite prolonged antibiotics (>4weeks), along with her previous response to a short course of granulocyte transfusion prompted us to prescribe a prolonged 10-day course of granulocytes with continued antibiosis. Her post-granulocyte CT showed resolution of her perirectal abscess and proctitis (figure 2). With resolution of her infection, she was able to proceed to HSCT which she completed without recurrence of her anorectal infection. Discussion: Conventional granulocyte transfusions are considered when patients have severe neutropenia (<500/uL), bacterial or fungal infection refractory to antimicrobials, and reasonable expectation of neutrophil recovery, but evidence for efficacy is limited. In our case, there was no expectation of imminent bone marrow recovery and our patient's infection limited her ability to proceed to IST or HSCT for treatment of her vsAA. Thus, in conjunction with infectious disease and transfusion medicine, and given her known response to granulocytes, we successfully re-attempted a prolonged, but limited, 10-day course of granulocyte transfusions and were able to eradicate a case of antibiotic-refractory proctitis with peri-anal fistula. We suggest an expanded application for the use of granulocytes in profoundly neutropenic patients without imminent recovery for severe, anti-microbial refractory infection. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Anal pain.

Anal pain.

Acute Gastrointestinal Toxicity Results from a Multi-Institution, Phase 2, Randomized Controlled Trial Comparing 3D-Conformal Radiotherapy (3DCRT) Versus Intensity Modulated Radiotherapy (IMRT) for Locally-Advanced Rectal Cancer (TRI-LARC).

<h3>Purpose/Objective(s)</h3> The primary aim of this trial was to compare the incidence of grade 2 or above acute gastrointestinal (GI) toxicity for patients undergoing 3DCRT versus IMRT in the preoperative setting for locally-advanced rectal cancer. Secondary objectives included quality of life and other acute and late toxicity. <h3>Materials/Methods</h3> The trial was designed to have 80% power to detect a difference between a hypothesized 37% acute toxicity rate in the 3DCRT arm (Bosset et al, 2006) and 20% in the IMRT arm, with a sample size of 120 per arm, and a 0.05 two-sided level of significance. Eligible participants were adults aged 18 or over scheduled to receive pre-operative pelvic chemo-radiotherapy for histologically-confirmed rectal adenocarcinoma. Exclusion criteria included prior pelvic radiotherapy, inflammatory bowel disease, hip replacements, and previous bowel surgery. Prescription dose was 50.4 Gray in 28 fractions over 5.5 weeks with concurrent 5-fluorouracil or capecitabine chemotherapy. Participants were centrally randomized 1:1 to receive 3DCRT or IMRT. Each individual radiotherapy volume and plan was reviewed centrally to ensure compliance with the trial's RTQA specifications. Toxicity was graded and reported according to CTCAE version 4.0 (National Institutes of Health National Cancer Institute). Acute toxicity was assessed weekly during radiotherapy, and at 2- and 4-weeks post-treatment. <h3>Results</h3> 94 patients were enrolled. 77% were male and median age was 59.4. Two participants from the 3DCRT arm did not complete radiotherapy as planned and were excluded from analysis. 25 (56%) of participants from the 3dCRT arm and 23 (49%) from the IMRT arm experienced acute grade 2 or above GI toxicity (p=.670). Rates for grade 3 GI toxicity were 8 (18%) and 5 (11%) for 3dCRT and IMRT, respectively (p=.494). Grade 3 GI events included diarrhea (n=11), nausea (n=2), intestinal obstruction (n=1), oral mucositis (n=1), and rectal pain (n=1). The study closed early due to absence of evidence of a difference between arms at the interim analysis. <h3>Conclusion</h3> No significant difference in rates of acute GI toxicity with IMRT versus 3DCRT for locally advanced rectal cancer was seen. Although IMRT can reduce dose to organs at risk, it appears to be similarly safe in terms of acute GI toxicity to deliver this treatment with 3DCRT.

The American Society of Colon and Rectal Surgeons Clinical Practice Guidelines for the Management of Anal Fissures.

The American Society of Colon and Rectal Surgeons Clinical Practice Guidelines for the Management of Anal Fissures.

Relationship Between Abuse History and Gastrointestinal and Extraintestinal Symptom Severity in Irritable Bowel Syndrome.

This study aimed to investigate the associations between the different abuse types, and gastrointestinal (GI) and extraintestinal symptom severity in irritable bowel syndrome (IBS), and possible mediators of these relationships. We assessed sexual and physical abuse in childhood and adulthood with the Drossman and Leserman abuse questionnaire, whereas GI and extraintestinal symptoms were assessed with the Gastrointestinal Symptom Rating Scale and the Symptom Check List-90 Revised. General linear models with bootstrapping tested the mediating role of depressive symptoms, anxiety symptoms, and GI-specific anxiety and rectal pain threshold. A path model analysis testing all relationships simultaneously was also performed. Among our 186 patients with IBS, an overall history of abuse (i.e., at least one type) was found in 37%. The effects of child and adult sexual abuse on GI symptom severity were fully mediated by GI-specific anxiety and rectal pain threshold (F = 21.540, R2 = 0.43, and F = 22.330, R2 = 0.44, respectively; p < .001 for both). The effect of adult sexual abuse and child physical abuse on extraintestinal symptom severity was fully mediated by GI-specific anxiety, depressive symptoms, and rectal pain threshold, whereas the effect of child sexual abuse was partially mediated (F = 14.992, R2 = 0.28; F = 15.065, R2 = 0.30; and F = 18.037, R2 = 0.32, respectively; p < .001 for all). When analyzed in a single path model, child sexual abuse and adult physical abuse only had a direct effect on extraintestinal symptom severity, whereas child physical abuse had an indirect effect through depressive symptoms. Abuse is associated with increased GI and extraintestinal symptom severity in IBS. These associations are mediated by levels of GI-specific anxiety, depressive symptoms, and rectal sensitivity.

PSAT303 Fecal Impaction as a Gastrointestinal Prodrome of Myxedema Coma in an Elderly Woman with Multiple Co-morbidities

Abstract Introduction Fecal impaction is a common occurrence in the elderly, with the most common risk factor being chronic constipation. A common cause of chronic constipation that can be overlooked in the elderly is hypothyroidism. If left untreated, hypothyroidism can have life-threatening manifestations including myxedema coma. In this case report, we describe a rare case of myxedema coma with prodromal fecal impaction. Case description An 87-year-old female with a past medical history of colon cancer status post partial colectomy, stroke, and end stage renal failure (ESRD) requiring hemodialysis, presented to the emergency department with extreme rectal pain. She was found to have fecal impaction on abdominal x-ray and was manually disimpacted and discharged home. Five days later, she presented with altered mental status in the setting of a new active herpes zoster infection and possible pneumonia. She was hypothermic (95F) and hypoxic, needing supplemental oxygen (2 L nasal cannula). Her labs showed hyponatremia (133 mg/dL), hypoglycemia (43 mg/dL), an elevated TSH level (100.0 mIU/ml) and decreased free T4 level (0.9 ng/L). Her EKG showed first-degree AV block with low voltage QRS complexes and her chest x-ray demonstrated bilateral pleural effusions. A CT scan of her head did not show hemorrhage or stroke. Given her classic clinical presentation and lab work findings, myxedema coma was diagnosed and the patient was treated with levothyroxine and hydrocortisone, though she was later transitioned to hospice as per her wishes. Discussion Chronic constipation is a known etiology of fecal impaction and can be caused by many chronic conditions in the elderly including ESRD, immobility, and hypothyroidism. Fecal impaction is easily identified but the investigation for the etiology is often overlooked. In this case, we argue that patients with an initial presentation of fecal impaction or with severe and unexplained constipation may warrant screening for hypothyroidism as a manageable risk factor for fecal impaction. By doing so, early recognition and treatment of hypothyroidism may prevent potentially fatal patient outcomes such as myxedema coma. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.

Type of Rectal Barostat Protocol Affects Classification of Hypersensitivity and Prediction of Symptom Severity in Irritable Bowel Syndrome.

Background/AimsVisceral hypersensitivity is an important pathophysiologic mechanism in irritable bowel syndrome (IBS). We compared 2 barostat distension protocols and their ability to distinguish between IBS patients and healthy controls, identify subjects with rectal hypersensitivity, and their associations with gastrointestinal symptom severity.MethodsWe retrospectively reviewed all patients at our unit that had undergone barostat investigations 2002-2014. Protocol 1 (n = 369) used phasic isobaric distensions with stepwise increments in pressure and protocol 2 (n = 153) used pressure controlled ramp inflations. Both protocols terminated when subjects reported pain or maximum pressure was reached. Thresholds for first sensation, urgency, discomfort and pain were established. Age- and gender-matched controls were used for comparison. The gastrointestinal symptom rating scale–IBS, and the hospital anxiety and depression scale were used for symptom reports.ResultsA significantly higher proportion of patients was classified as having hypersensitivity in protocol 1 vs protocol 2 for all thresholds (P < 0.001). Patients with visceral hypersensitivity, defined based on rectal pain thresholds in protocol 1 had more severe gastrointestinal symptoms overall as well as anxiety, whereas these associations were weaker or in most cases absent when visceral hypersensitivity was defined based on rectal pain thresholds in protocol 2.ConclusionOur study indicates that a rectal barostat protocol using phasic isobaric distensions with stepwise pressure increments is more sensitive in IBS patients with respect to identifying subjects with rectal hypersensitivity and a link with IBS symptoms.

Clinical and Epidemiological Features of Hospitalized and Ambulatory Patients with Human Monkeypox Infection: A Retrospective Observational Study in Portugal.

Monkeypox, a neglected and re-emergent zoonotic disease caused by monkeypox virus (MPXV) infection, has been endemic in Central and Western Africa for decades. More recently, an outbreak has spread to a global level, occurring in sites with no previous reported cases and being clustered among men who have sex with men, suggesting new modes of transmission. There is an urgent need for research for a better understanding of the genomic evolution and changing epidemiology of the Orthopoxvirus group. Our work aimed to characterize the clinical and epidemiological features of a cohort of patients with MPXV infection in a Portuguese hospital, admitted between 5 May and 26 July 2022. In this retrospective observational study, aggregate data of a case series on the presentation, clinical course, and outcomes of confirmed MPXV infections are reported. The study included 40 men and 1 woman, with a mean age of 37.2 years old; 92.7% identified as men who have sex with men, 90.2% had unprotected sex or sex with multiple or anonymous partners in the previous month, and 39.0% reported to have had sex with an MPXV-confirmed case; 59.5% had previously known human immunodeficiency virus (HIV) infection, all of whom were under antiretroviral therapy, and no patients had acquired immunodeficiency syndrome (AIDS) criteria. About a quarter of patients were observed only a week after symptom onset. All patients had skin or mucosal lesions and the anogenital region was the most frequent lesion site. There were no statistically significant clinical differences between HIV-positive and negative individuals. Four patients were admitted to the inpatient clinic, two of whom had proctitis with difficult-to-manage anal pain. There were no reported deaths. Our findings suggest the sexual route as a relevant mode of transmission of MPXV and confirm the mostly benign presentation of this disease.

Retrospective Analysis of Proton Beam Therapy for Postoperative Locally Recurrent Rectal Cancer

<h3>Purpose/Objective(s)</h3> The outcomes of postoperative locally recurrent rectal cancer (PLRRC) are unsatisfactory in the multimodal treatment era. We retrospectively analyzed the outcomes of proton beam therapy (PBT) for PLRRC at our institution. <h3>Materials/Methods</h3> We included 79 PBT-treated PLRRC patients between December 2008 to December 2019. We excluded patients with prior history of salvage surgery, radiotherapy, or distant metastasis before PBT, and those treated with postoperative adjuvant PBT. We included patients who had history of chemotherapy. We estimated the overall survival (OS), disease-free survival (DFS), and local control (LC) using the Kaplan–Meier method. The prognostic factor for each outcome was verified using a Cox proportional hazards model. <h3>Results</h3> We enrolled 23 patients. The median follow-up time was 36.8 months. The median age was 64 (range, 34–83) years. The median time from surgery to recurrence was 18.1 months. Twenty patients (87%) had adenocarcinoma, two had carcinoid, and one had neuroendocrine carcinoma. The postoperative recurrent sites were presacral (12 patients), pelvic side wall (seven patients), and anastomoses (four patients). The median recurrent tumor size was 37 (range, 16–130) mm. The median maximum standardized uptake value (SUV_max) of Fluorine-18-fluorodeoxyglucose-positron emission tomography/computed tomography (18^F-FDG-PET/CT) before PBT was 7.4. Twenty-one patients (91%) received PBT alone. The median total dose was 72.6 (range, 60–87) Gy relative biological effectiveness. The treatment response was stratified by initial imaging (median, two months) after PBT. Of 23 patients, 16 (70%) received 18^F-FDG-PET/CT for initial imaging modality. Eleven patients had complete response (CR), eight had partial response, two had stable disease, and two had progressive disease. Eleven patients (48%) had lumbar or anal pain before PBT and had symptomatic pain improvement after PBT. Three- and five-year OS, DFS, and LC were 71.5%/43.3%, 37.3%/37.3%, and 54.5%/46.7%, respectively. The SUV_max of 18^F-FDG-PET/CT before PBT (cut-off value:10) showed significant difference for OS (<i>P</i>=0.0135), DFS (<i>P</i>=0.047), and LC (<i>P</i>=0.0239). The patients who achieved CR after PBT had significantly better LC compared with those with non-CR (HR 4.71, 95% CI 1.18–18.65, <i>P</i>=0.0177). Elderly patients (≧65 years) had significantly better LC and DFS. The patients with pain before PBT and larger tumor (≧30 mm) also had significantly lower DFS. Of 23 patients, 12 (52%) had further local recurrence after PBT. One patient developed grade 2 acute radiation dermatitis. Grade 4 late gastrointestinal toxicity (perforation) was recorded in three patients, two of which were associated with reirradiation for further local recurrence after PBT. <h3>Conclusion</h3> The outcomes of PBT for PLRRC are better than those of conventional photon therapy, and are comparable with those of surgery. 18^F-FDG-PET/CT before/after PBT correctly reflected the treatment effect and prognosis.

Imaging features of anorectal proctitis in monkeypox infection

The monkeypox outbreak of 2022 saw the first community-sustained transmission of the monkeypox virus outside of Africa, and rapidly developed into multi-country spread. A common presenting sign of monkeypox infection during this outbreak has been rectal pain due to proctitis. Proctitis with large hypoattenuated anorectal ulcers on CT scan should invoke consideration for monkeypox infection in young homosexual or bisexual men with associated skin eruptions.

An Unusual Cause of Diarrhea in Young Adulthood

Question: A 31-year-old woman presented to the gastroenterology clinic for a second opinion regarding chronic intermittent abdominal pain and alternating diarrhea and constipation for more than 10 years. She occasionally noticed a greasy film on the toilet water, but there was no blood in the stool, rectal pain, or weight loss. She had undergone computed tomographic (CT) imaging about 10 years before presentation for similar symptoms (Figure), and recently underwent esophagogastroduodenoscopy and colonoscopy with normal duodenal and colon biopsies, respectively.

Electron microscopy images of monkeypox virus infection in 24-year-old man

A 24-year-old man presented to our clinic reporting severe anal pain and a pustular rash on his trunk, arms, penis, and fingers. The patient said the pain started 3 days after he had condomless penetrative and receptive anal intercourse with a man; he then developed a fever, chills, and inguinal lymphadenopathy. The skin lesions appeared approximately 8 days after the sexual activity: 2 days before he attended our clinic. The patient was previously fit and well with no medical history.

S2233 Anorectal Melanoma

Introduction: Mucosal melanoma is rare and accounts for approximately 1% of all melanomas. Mucosal melanomas occur primarily in the head and neck (55%), anorectal, and vulvovaginal regions (18%). Anorectal mucosal melanoma accounts for 0.05% of all colorectal malignancies and 1% of all anal canal cancers. Case Description/Methods: A 61 year-old-male patient with no significant past medical history presented to the hospital with anal pain for one month with subsequent rectal bleeding. On examination, his heart rate and blood pressure were within normal limits. His digital rectal exam was remarkable for a palpable anorectal mass. His blood tests showed no anemia. Colonoscopy revealed a large non-obstructing cauliflower mass occupying the anorectum with overlying friable mucosa that easily bleeds on touch (Figure A, B). Histopathology showed undifferentiated spindle and round cell malignancy consistent with nodular type of malignant melanoma. Immunohistochemical staining revealed strong positivity for S100, Melan A, and HMB45 markers confirming the diagnosis of malignant melanoma. Magnetic resonance imaging (MRI) of the abdomen and pelvis redemonstrated a large anorectal endoluminal mass lesion with multiple enlarged presacral and bilateral internal iliac lymph nodes. Positron emission tomography-computed tomography scan (PET-CT) showed a fluorodeoxyglucose (FDG)-avid anorectal wall thickening and internal iliac lymph nodes. After a multidisciplinary team discussion, the patient underwent abdominoperineal resection with bilateral iliac lymph nodes dissection (Figure C). Discussion: Malignant melanoma of the anorectum is a rare mucosal neoplasm that typically presents in the fifth or sixth decade. Mucosal melanoma occurs in the anorectum due to abundance of the melanocytes in the mucosa of the anal canal. It usually presents with nonspecific complaints such as anal pain or rectal bleeding that can be misdiagnosed as hemorrhoids or rectal polyps and lead to delayed diagnosis. Surgical resection is the mainstay of treatment, while the benefit of radiotherapy and chemotherapy remains uncertain. This tumor is an aggressive tumor that carries a poor prognosis; and even with surgical intervention, the reported 5-year overall survival rate is 6%–15%.Figure 1.: Endoscopic image of the anorectal mass lesion on retroflection (A) and with the i-Scan (B). (C) Abdominoperineal resection with bilateral iliac lymph nodes dissection.

S2594 Hematochezia and a Messy Malignant Melanoma

Introduction: Lower gastrointestinal bleeding is a common complaint amongst patients seen in the outpatient setting and carries a wide differential diagnosis. This ranges from benign conditions such as hemorrhoids, angioectasia, diverticulosis, anal fissures, etc., to serious, life-threatening conditions including malignancy. We present a unique case of rectal bleeding caused by anorectal melanoma. Case Description/Methods: A 50-year-old Hispanic female with history of hypertension presented to her primary care physician for rectal bleeding. She endorsed two months of constipation, decreased caliber of stools, and intermittent hematochezia. Her physical exam revealed a rectal prolapsing mass, and laboratory results revealed a hemoglobin of 12.3 g/dL, unchanged from prior. Due to these findings, she was referred to gastroenterology for evaluation. The patient underwent a colonoscopy which demonstrated a large, non-circumferential, three centimeter, partially obstructing mass in the rectum. The mass appeared to originate from the dentate line. No bleeding was present, however the mass appeared vascular in nature with dark purple areas, suggestive of a large thrombosed hemorrhoid. She was referred to the advanced endoscopists for an endoscopic ultrasound, which showed a hyperechoic mass with internal hypoechoic regions suggestive of necrosis. The endosonographic borders were well defined and the mass appeared confined to the mucosa. Biopsies were obtained and histopathology demonstrated atypical cells with prominent nucleoli and melanin pigment. The cells were positive for MART-1 and SOX10, confirming the diagnosis of malignant melanoma. A CT of the chest, abdomen, and pelvis was negative for lymphadenopathy or metastatic disease. She was referred to colorectal surgery and underwent local excision (Figure 1). Discussion: Melanoma can arise from the mucosal epithelium of the respiratory, gastrointestinal, or genitourinary tracts in addition to the skin. Mucosal melanoma accounts for approximately 1.3% of all melanoma and usually carries a worse prognosis. Anorectal melanoma accounts for 1% of all anal canal malignancies. Symptoms can include rectal bleeding, anal pain, and change in bowel habits. The diagnosis is often missed as the signs and symptoms can be mistaken for hemorrhoids or polyps. Anorectal melanoma can even appear amelanotic, making the diagnosis more difficult. It is important for endoscopists to consider anorectal melanoma as a diagnosis as early detection and treatment is associated with improved prognosis.Figure 1.: (A) Large rectal mass visualized during colonoscopy (B) Tumor with melanin pigment undermining squamous mucosa (H&E, 20×).