Human herpesvirus-8 positive iatrogenic Kaposi's sarcoma in the setting of refractory ulcerative colitis

Although Kaposi sarcoma (KS) has been more traditionally considered an AIDS-defining illness, it may also be seen in individuals on immunosuppresive therapy. We report a case of a patient who presented to the hospital in the setting of increasingly refractory ulcerative colitis. Computed tomography scan of the abdomen was consistent with sigmoid diverticulititis and blood cultures were positive for Klebsiella. After a course of antibiotics with resolution of infection, a colonoscopy was performed to evaluate his diverticulitis and incidentally revealed a new rectal tumor. Immunohistochemistry showed the tumor was consistent with KS, with cells staining strongly positive for human herpesvirus-8. This case not only illustrates a rare case of KS found in an HIV-negative individual, but it also highlights the importance of considering an alternative diagnosis in a patient refractory to medical treatment. We discuss the management and care of an ulcerative colitis patient diagnosed with KS on immunosuppressive therapy.