Colonic Leishmaniasis Mimicking a Malignant Stricture: Initial Presentation of Human Immunodeficiency Virus Infection - A Case Report.

Colonic involvement in visceral leishmaniasis (VL) is exceptionally rare. We report a case of a 39-year-old man who presented with anorexia, weight loss, and diarrhea. Imaging revealed hepatosplenomegaly and extensive retroperitoneal lymphadenopathy, while laboratory tests showed pancytopenia and renal dysfunction. He was newly diagnosed with human immunodeficiency virus (CD4+ count: 3 cells/μL), and VL was confirmed by identification of amastigotes and positive PCR in bone marrow aspirate. During hospitalization, he developed severe hematochezia. Colonoscopy revealed a pseudotumoral, ulcerated, and stricturing lesion in the ascending colon; histology confirmed colonic leishmaniasis. The patient progressed to hemorrhagic shock, requiring urgent right hemicolectomy. This case underscores an uncommon and fulminant presentation of VL in the setting of profound immunosuppression, highlighting the importance of considering parasitic infections in the differential diagnosis of gastrointestinal bleeding in HIV-positive individuals.