Gastroduodenal Kaposi Sarcoma Without Cutaneous Lesions in an Immunosuppressed Patient

Kaposi sarcoma (KS) is an angioproliferative neoplasm that develops as a result of infection with human herpesvirus 8 (HHV-8). The disease most commonly appears as painless, nonpruritic, violaceous papules, plaques, or nodules on the skin, but it can also affect lymph nodes, mucosal surfaces, and internal organs. A 53-year-old man from Guinea-Bissau with membranous nephropathy who was being treated with prednisolone and cyclophosphamide presented with abdominal pain, early satiety, anorexia, and fever. His symptoms emerged while he was taking antibiotics for a recent respiratory tract infection. Physical examination showed epigastric tenderness and bilateral ankle edema. Abdominopelvic CT revealed loss of the fat plane between the pancreatic head and the duodenum, along with multiple mesenteric and peripancreatic lymph nodes, some of which had necrotic changes. Serologic testing for HIV was negative, and both blood and mycobacterial cultures did not grow any organisms. Upper gastrointestinal endoscopy demonstrated lobulated, erythematous lesions in the gastric body, with similar changes in the duodenal bulb and the second portion of the duodenum. Biopsy showed a spindle-cell neoplasm, and immunohistochemistry confirmed KS, establishing the diagnosis of iatrogenic KS with gastroduodenal involvement. This HIV-negative case highlights that gastrointestinal KS should be considered in patients who are immunosuppressed due to medical therapy.