MALAKOPLAKIA OF THE URINARY BLADDER AND COLON AS A MIMIC OF LOCALLY ADVANCED MALGINANCY IN A RENAL TRANSPLANT RECIPIENT: A CASE REPORT

Middleton W1, Govindarajulu S1

1Toowoomba Hospital, Toowoomba, Australia

Background: Malakoplakia is a rare granulomatous disease seen in immunosuppressed patients, including renal transplant recipients. It is usually associated with recurrent urinary tract infection (r-UTI), particularly gram-negative rods.

The pathogenesis is hypothesised to be due to impaired phagolysosomal degradation of bacteria by macrophages and monocytes. It has been described in almost every organ system but most commonly affects the urinary tract. Macroscopic appearance can include plaques, nodules, and masses that can be mistaken for tumours and hence histology is fundamental to aid with the diagnosis.

Case Report: A 53-year-old male, renal transplant recipient,  presented with increased urinary frequency and r-UTI with pseudomonas and E.Coli 12 months post transplant.

He had an episode of sigmoid diverticulitis treated successfully two months before presentation with r-UTI, and cadaveric renal transplant 12 months prior for autosomal dominant polycystic kidney disease. He had previously been treated with anti-thymocyte globulin for borderline acute cellular rejection and was on tacrolimus, mycophenolate and prednisolone at the time of presentation.

Ultrasound of the transplant kidney and a subsequent Computerised tomography scan demonstrated a lobulated, hyperattenuating irregular mass in the bladder with continuity to adjacent sigmoid colon. Colonoscopy did not demonstrate an intraluminal lesion. Cystoscopy revealed a colovesical fistula and a biopsy of the lesion was consistent with malakoplakia with the pathognomonic findings of Michaelis-Guttman bodies, histiocytes infiltrating the lamina propria of the bladder mucosa. The fistula was corrected with high anterior bowel resection and wedge cystectomy.

Conclusions: Malakoplakia is a rare disease seen in renal transplant patients that can mimic tumours and histology is fundamental to aid with the diagnosis. Awareness of this condition is important


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