S5184 When Kaposi Sarcoma Stays Within: A Unique Case of Isolated Colonic Kaposi Sarcoma with Concurrent Cytomegalovirus Infection

Introduction: Kaposi sarcoma (KS), a well-established AIDS-defining malignancy, arises from infection with human herpesvirus-8, promoting development of low-grade vascular tumors predominantly affecting mucocutaneous sites. While gastrointestinal (GI) tract involvement is a recognized feature of AIDS-associated or ‘epidemic’ KS, it typically occurs in conjunction with cutaneous lesions. GI exclusive sarcomatous lesions are an exceedingly rare manifestation in those with epidemic KS. Colonic cytomegalovirus (CMV) infection is also a co-occurrence infrequently reported. We describe a unique instance of KS with exclusive GI involvement, likely promoted by CMV co-infection. Case Description/Methods: A 38-year-old man with uncontrolled HIV noncompliant with HAART, syphilis, and intravenous drug use presented complaining of chronic diarrhea. He reported year-long, non-nocturnal diarrhea, characterized by 7-8 loose bowel movements daily associated with dyschezia. Examination revealed diffuse abdominal tenderness, distention, external hemorrhoids, and diminished bilateral lower extremity strength. He had no cutaneous lesions. Laboratory studies noted hyponatremia (125 mmol/L), normocytic anemia, and acute kidney injury. CD4+ count was 52/mcL. Infectious studies showed HIV RNA 855,755 copies/mL, RPR titer of 1:128, and stool positivity for Shigella and Entamoeba histolytica. Abdominal imaging revealed active mild-to-moderate long-segment colitis and moderate ascites. ID restarted HAART, along with ciprofloxacin, metronidazole, and penicillin. After 2 weeks, CD4+ count improved (151 cells/mcL). His diarrhea persisted, now refractory to antimicrobials and antidiarrheals. Colonoscopy showed nodular erythematous mucosa in the descending and transverse colon with severe inflammation and luminal narrowing from the rectum to sigmoid colon. Pathology confirmed the diagnosis of Kaposi sarcoma, and immunohistochemical staining also demonstrated concurrent CMV infection within the colonic mucosa. Discussion: Isolated gastrointestinal involvement is only noted in about 10-15% of endemic KS cases. Visceral involvement of KS, without identifiable skin manifestations, may lead to a delay in diagnosis, as was the case in our patient, ultimately delaying treatment. Furthermore, CMV co-infection has been implicated in the development or progression of KS lesions. Understanding internal involvement of AIDS-defining illnesses, by the physician and patient, will aid efficient care and HAART compliance.