Prostatic Malakoplakia: Case Report and Review of the Literature

Abstract

Abstract A 69-year-old Asian man with a history of overactive bladder presented with postvoid dribbling and urinary incontinence in the past three years. He had cervical spinal stenosis surgery one month ago and two episodes of urinary tract infections with multidrug-resistant Escherichia coli species in urine culture in the last three months. Digital rectal examination revealed a 1-cm hard nontender nodule within the right side of his prostate, concerning for possible prostatic malignancy. Ultrasound study identified a hypoechoic area in the right lateral prostate. Serum prostate-specific antigen level was 2.03 ng/mL (reference range, ≤5.40 ng/mL). Biopsies of the prostate showed only focal chronic inflammation in the left lobe, but there were collections of abundant histiocytes with associated plasma cells and lymphocytes, as well as fibrosis in 5 of 7 cores in the right lobe. Within the histiocytic infiltrate, abundant Michaelis-Gutmann bodies, both intracytoplasmic and extracellular, were identified and confirmed with periodic–acid Schiff and von Kossa stains. The morphologic features and histochemical stains support the diagnosis of malakoplakia. So far, 68 cases of prostatic malakoplakia including ours have been reported (mean age, 63.5 years). Most patients presented with urinary tract symptoms and positive urine culture for E. coli. Eight patients also had associated prostatic adenocarcinoma. Serum prostate-specific antigen may be significantly elevated in patients with prostatic malakoplakia without associated adenocarcinoma. Prostatic malakoplakia can clinically and radiographically mimic prostatic adenocarcinoma. Pathologically malakoplakia should be distinguished from granulomatous prostatitis and other benign and malignant prostatic diseases.