Prototheca zopfii associated diverticulitis in an immunosuppressed host, a case presentation and literature review

Clinical infection with Prototheca species can present in many ways including cutaneous, bursal, or disseminated forms. Of these clinical forms, protothecal intestinal infections are a very rare occurrence, and there have only been a few documented cases within the medical literature. We present a case of a 67 year old African American male who presented to our veterans hospital with bowel obstruction. The patient has a pertinent medical history of prolonged immunosuppressive therapy for cadaveric renal transplant, Clostridium difficile infection, herpetic perirectal ulcer, and diverticulosis. The patient presented with symptoms of weight loss, left lower quadrant pain, and pencil thin stool. Colonoscopic and barium studies confirmed a complete obstruction at the level of the distal descending colon. Carcinoembryonic levels were within normal limits. The patient underwent a left hemicolectomy, and gross examination of the specimen revealed a markedly thickened bowel wall with multiple diverticula. Histologic examination revealed diverticular disease with associated transmural inflammation and numerous associated dark round structures. The basophilic round structures appeared to contain cell walls and stained positively for fungal stains. Overall, the diagnosis of Prototheca zopfii was made based on the characteristic histopathologic features and the results of the fungal staining pattern. To our knowledge, this is the first reported case of a colonic diverticulitis with involvement by Prototheca zopfii. We present an overview of the biology, epidemiology, histopathologic features, clinical manifestations, and treatment options of Prototheca as it relates to our patient