Gastroenterology clinical image challenge: A 51-year-old Asian man has a known history of AIDS on antiretroviral therapy with dolutegravir and emtricitabine/tenofovir. He presented with a one-month history of proctalgia, abdominal pain and bloody diarrhea with urgency about 11 times per day. He was previously treated for PCP pneumonia and otherwise he has no significant past medical history. He was first evaluated by a gastroenterologist at an outside clinic for his symptoms.
Routine stool studies did not reveal an infectious cause of diarrhea. A computed tomography scan of the abdomen and pelvis showed rectal wall thickening, perirectal fat stranding and lymphadenopathy. Colonoscopy revealed severe erythema, edema, friability and granularity in the rectum about 15 cm, confirming severe proctitis. He had acute and chronic inflammation with necrosis on histopathology. Upper endoscopy showed hiatal hernia and pyloric ulcers that tested negative for Helicobacter pylori. The patient was presumptively diagnosed with Crohn’s disease and treated with rectal budesonide and metronidazole for 21 days with no improvement. He had progressive proctalgia, diarrhea and a weight loss of 41 lbs over the following two months.
He presented to our hospital for a second opinion. His CD4 count one month earlier was 700 cells/μL and the current CD4 count was 330 cells/μL. Repeat colonoscopy showed multiple rectal ulcers sparing the colon and terminal ileum (figure). Histopathology showed chronic active proctitis with ulcerated mucosa suggestive of inflammatory bowel disease. The examination was negative for dysplasia, and immunohistochemistry for cytomegalovirus and herpes simplex virus infection was negative. Given that the patient experienced poor response to previous treatment with steroids, further workup was initiated.
What is the diagnosis? And what is the best next step?
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