1924 Bleeding Beyond the Line: Anorectal Melanoma as a Cause of Lower Gastrointestinal Bleeding

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INTRODUCTION: Anorectal melanoma is a rare malignancy that can present as hematochezia similar to other gastrointestinal bleeding sources. The diagnosis of anorectal melanoma may be challenging given its rarity, nonspecific presentation, and need for histopathology, but accurate and timely diagnosis is essential given that associated bleeding may not respond to conventional treatments. CASE DESCRIPTION/METHODS: An 88-year-old male was admitted for septic shock after being found lethargic at his nursing facility. He was started on intravenous antibiotics and vasopressors and intubated for airway protection. Though slowly improving overall, on hospital day 6, he had 4 episodes of large red clots per rectum. Rectal examination showed bright red blood and a rubbery mass palpable on the posterior rectal wall without visible hemorrhoids. Due to the acute drop in hemoglobin to 6.3 g/dL, the patient was transfused 2 units of packed red blood cells, empirically started on intravenous pantoprazole, and administered parenteral Vitamin K and a dose of desmopressin. Over the next two days, the patient continued to have multiple bowel movements with blood clots requiring additional blood transfusions. Given these findings, the patient underwent flexible sigmoidoscopy. DISCUSSION: Flexible sigmoidoscopy revealed a 3 cm ulcerated mass in the distal rectum which involved the dentate line. Endoscopic hemostasis was not feasible, but a biopsy was obtained which showed malignant melanoma invading the lamina propria and muscularis with associated ulceration. Considering the patient's age, clinical status, and advanced dementia, the medical team and unrepresented patient committee agreed that it was ethically appropriate to not pursue further work-up or treatment of the patient's melanoma. Following medical stabilization, the patient was transitioned to home comfort care. This case illustrates a rare etiology of bright red blood per rectum and the importance of additional investigation in the setting of clinically significant anemia and/or inadequate response to conservative measures. Anorectal melanoma, similar to other rare disorders which can mimic internal hemorrhoidal bleeding, frequently requires endoscopic techniques for diagnosis and management. Despite this patient's clinical course and the generally poor prognosis of anorectal melanoma, early diagnosis can allow for surgical excision and/or adjuvant therapies that may provide a potentially curative outcome or delay disease progression and mitigate bleeding complications.