Diagn Pathol 2019 Mar 13;14(1):22. Epub 2019 Mar 13.
Department of Radiology, Maisonneuve-Rosemont Hospital, 5415 Boulevard de L'Assomption, Montreal, QC, Canada.
Background: Malakoplakia is a chronic inflammatory disease characterized by tissue infiltrates of large granular macrophages containing distinctive intracytoplasmic inclusions termed Michaelis-Gutmann (MG) bodies. The genitourinary system is the most commonly involved site, followed by the gastrointestinal tract. Malakoplakia may occur as a complication of primary or secondary immunosuppression and, therefore, renal transplant recipients are at risk. The graft itself or extra-renal sites may be involved. Regarding the latter, six cases of colorectal malakoplakia have been reported following renal transplantation, with all but one patient experiencing significant morbidity. We describe a further example of colorectal malakoplakia following renal transplantation. The other previously reported cases are reviewed.
Case Presentation: A 72 year old female presented with left lower quadrant abdominal pain and vaginal bleeding. She had received a cadaveric renal transplant for chronic renal failure ten months previously. Abdomino-pelvic computerized tomography (CT) scanning demonstrated two lesions in the mesocolon: the first adjacent to the descending colon and the second involving the sigmoid colon. A diagnosis of sub-acute perforated diverticulitis with two phlegmons was proposed. The sigmoid lesion was resected. The descending colon lesion was treated by creation of a cutaneous fistula. Microscopy of the sigmoid lesion showed the typical features of malakoplakia. She was discharged on sulfamethoxazole-trimethoprim. Nine months later, no longer receiving antibiotic therapy, the patient reported lower left quadrant discomfort. CT scanning showed para-rectal and pelvic abdominal masses with cutaneous and intestinal fistulas. Treatment with tazobactam-piperacillin was begun and sulfamethoxazole-trimethoprim was reinstated, with subsequent slow clinical improvement. Subsequent abdominal CT scans have shown persistence of the lesions.
Conclusions: Physicians caring for renal transplant recipients should be aware of colorectal malakoplakia as a rare but serious complication. The onset may be within months or as long as a decade or more following transplantation. The clinical presentation is varied, nonspecific, and will likely suggest more common diseases. Although radiologic imaging is also nonspecific, awareness of malakoplakia is of importance to radiologists when formulating the differential diagnosis of mass lesions of the colorectum in this clinical setting. Definitive diagnosis remains dependent on pathologic examination of a biopsy or surgical resection specimen.