A Painful Perianal Lesion

Abstract

Gastroent Question: A 54-yearold white man with a history of infection with human immunodeficiency virus complicated with disseminated bartonellosis infection was recently diagnosed with multicentric Castleman disease. He was treated with 4 weekly doses of rituximab 375 mg/m and methylprednisone 4 mg/d. His further treatment consisted of ritonavir boosted daranuvir, emtricitabin, and tenofovir. His CD4 count was 100/ mL, and his viral load 151 copies/mL. During his second course of chemotherapy, he developed complaints of anal pain and rectal bleeding. On physical examination, he had a deep, solitary, punched-out perianal ulcer with granulating base and raised indurated edges (Figure A). His leukocyte count was 3400/mL, with 59% neutrophils and 34% lymphocytes. Serological testing was negative for Bartonella henselae immunoglobulin M enzyme-linked immunosorbent assay and Treponema pallidum rapid plasma reagent. Tissue cultures of the ulcer were negative for fungi, mycobacteria and pathogenic bacteria, as was the polymerase chain reaction (PCR) for Chlamydia trachomatis and Neisseria gonorrhoeae and the direct immunofluorescence assay for Herpes simplex types 1 and 2. Biopsies from the border of the ulcer showed a mixed inflammatory infiltrate (mainly consisting of neutrophils, without granuloma formation) in the basal layer of the stratified squamous epithelium (Figure B, arrow). Specific staining could not demonstrate any acid-fast bacilli, fungi, or herpesvirus antigens. What are major differential diagnoses, and how may you proceed? See the Gastroenterology web site (www.gastrojournal.org) for more information on submitting your favorite image to Clinical Challenges and Images in GI.