Colonic Mass and Chronic Diarrhea in a Renal Transplant Patient: An Uncommon Case of Malakoplakia

Abstract

Introduction: Malakoplakia is an uncommon chronic granulomatous disease that is histologically characterized by diffuse histiocytic infiltration (von Hansemann's cells) with eosinophilic granular cytoplasm containing the basophilic, laminated cytoplasmic inclusions called Michaelis-Gutmann bodies. With the urinary tract being the most commonly affected site, other affected areas may include colorectum, stomach, gall bladder and pancreas. We report a case of malakoplakia presenting as a partially obstructing sigmoid colon mass with chronic diarrhea in a renal transplant patient. Case presentation: A 68-year-old man with end stage renal disease post kidney transplantation was admitted to our hospital for generalized weakness, poor appetite, chronic diarrhea and weight loss. Physical examination was unremarkable except for dry oral mucosa. Laboratory workup revealed acute kidney injury and hyperkalemia. Stool infection studies were negative. At colonoscopic exam, a partially obstructing polypoid mass was found in the sigmoid colon (Fig. A). Biopsies revealed ulcerations, granulation tissue and marked submucosal histiocytic proliferation. Von Kossa calcium stain revealed several Michaelis-Gutmann bodies (Fig. B). Malakoplakia of sigmoid colon was diagnosed and patient was treated with ciprofloxacin 250 mg twice daily for 6 months. Chronic diarrhea resolved after treatment and a 6-month follow-up colonoscopy revealed a small residual mucosal lesion in the area of the prior mass lesion (Fig. C).Figure: Endoscopic appearance of sigmoid colonic mass at presentation.FigureFigure: Follow-up colonoscopic appearance of sigmoid colon malakoplakia after 6 month of treatment.Discussion: Although the etiology is still unclear, there has been increasing number of reported cases of malakoplakia in immunocompromised individuals, such as organ transplant patients. Some investigators believe the origin to be infectious (e.g. E. coli) and others believed that the diminished capacity of macrophages for lysis of bacteria leads to deposition of calcium and iron in the underlying defect (1). Endoscopic manifestations of malakoplakia of the colon have been described in 3 different forms: 1) isolated sessile/polypoid masses in the rectosigmoid colon, 2) diffuse serpiginous lesions or ulcers of the colon, 3) mass occurring in association with cancer of the colon. It is associated with colorectal cancer in up to 30%. Management with the appropriate antibiotics regimen that concentrate in the macrophages is a key step in the management, and raising awareness among gastroenterologists regarding this uncommon entity and its potential cure is fundamental.