Plasmoblastic lymphoma as cause of perianal fistula: a case report and literature review.

We report the case of a 33-year-old HIV-infected man who presented with a recurrent, nonhealing perianal fistula. After multiple benign biopsies, the diagnosis of plasmablastic lymphoma (PBL) eventually was made. The patient underwent chemotherapy and radiation with a complete response. Perianal fistulas are frequent in HIV-positive patients, but PBL as a cause is extremely rare. This often delays the diagnosis and treatment of this highly aggressive disease. We review the literature and discuss the pitfalls in the diagnosis and management of the disease.