Gastrointestinal Kaposi Sarcoma in Inflammatory Bowel Disease: Clinicopathological, Endoscopic, and Follow-Up Study of 6 Patients With Review of the Literature.

Gastrointestinal Kaposi sarcoma (GI-KS) in inflammatory bowel disease (IBD) is exceedingly rare. Herein, we report 6 biopsy-proven HHV8(+)-GI-KS in IBD patients with a review of the literature. Our patients include 5 men and 1 woman, 26 to 41 (mean = 34) years, 3 Crohn disease, 3 ulcerative colitis (UC), 4 HIV(+), and 2 HIV(-), with 5 of 6 (83%) diagnosed with GI-KS on endoscopic biopsy. Tumor sites included stomach and rectum (2/6; 33% each), and duodenum and left colon (1/6; 17% each). In 1 HIV(-) patient, GI-KS was missed on the initial biopsy and identified at total colectomy for "refractory" UC; besides the rectal tumor, the appendix and a lymph node were also involved. Endoscopy showed flat or mass-like lesions (3/6; 50% each). Histologically, GI-KS shows a classic morphology of spindle cell proliferation in 4 (67%) and subtle paucicellular variants in 2 (33%) patients. All patients were treated with chemotherapy or surgery, with highly active antiretroviral therapy added for all HIV(+) patients. On follow up (mean = 64.7, median = 55.5, range = 6-162 months), all patients were alive with endoscopic remission (3/5; 50%), stable or improved IBD, and no disseminated disease. Fifteen patients with HHV8(+) GI-KS were previously reported, with 54% diagnosed only after surgery, suggesting a high false-negative rate on endoscopic biopsy. In conclusion, GI-KS rarely occurs in IBD, appears to have a high risk of being missed on endoscopic biopsy, has a good outcome, and should be considered in patients with "refractory" IBD. Multiple sites of involvement do not portend a worse prognosis. Accurate diagnosis is essential to initiate appropriate therapy, since IBD immunosuppressive regimens may exacerbate GI-KS.