19. The many faces of colonic malakoplakia: A case series and review of the literature

Abstract

Background: Malakoplakia is a rare inflammatory response to Gram-negative bacteria, involving intracellular deposition of iron and calcium. It is associated with immunosuppression, and occurs most often in the bladder. Although rare, the colon is the most common extra-genitourinary site. Aims and methods: To identify cases of colonic malakoplakia, the Royal Prince Alfred Hospital histopathology data base was searched from 2009. A literature review was performed using PubMed with the term ‘malakoplakia’. Formalin-fixed paraffin-embedded slides were stained with haematoxylin and eosin, PAS and von Kossa. Results and conclusions: A 10-year case file review identified four cases of colonic malakoplakia. Ages ranged from 50–79 with 2 males and 2 females. Clinical presentation and endoscopic appearances varied widely with an incidental polyp, mucosal changes mimicking inflammatory bowel disease, and a pelvic mass lesion with overlying normal mucosa seen. In all cases the biopsies revealed numerous histiocytes and chacteristic Michaelis-Gutmann bodies highlighted with PAS and von Kossa stains diagnostic of malakoplakia. A literature review identified 31 published case reports in adults and 10 in children of colonic malakoplakia. These cases highlight the protean manifestations of colonic malakoplakia. Consideration should be given to the diagnosis in histiocytic infiltrates in the large bowel to facilitate appropriate clinical management.