Background: Malakoplakia is a rare, granulomatous disorder that is typically triggered by infections in immunocompromised patients and most commonly affects the bladder. Herein, we report the seventy-fourth case of prostatic malakoplakia in the world literatures and the first case reported in Thailand. The paper will also be the first to compare the multiparametric (mp) magnetic resonance imaging (MRI) of malakoplakia before and after treatment, for differentiating the combined concurrence of malakoplakia and prostatic adenocarcinoma.

Case Report: A case of prostatic malakoplakia in a 70-year-old Thai man with a history of recurrent urinary tract infections who presented with acute urinary retention and prostatitis. An mpMRI study showed a Prostate Imaging- Reporting and Data System (PI-RADS) 5 lesion. His serum prostate specific antigen level (PSA) had risen to be 47.53 ng/mL. All findings strongly indicated prostate cancer. The patient underwent MRI-TRUS (Transrectal ultrasound) fusion-guided prostate biopsy and pathology slides revealed, microscopically, macrophages known as von Hansemann cells with scattered targetoid intracytoplasmic inclusions known as Michaelis-Gutmann bodies. He underwent transurethral resection of the prostate combined with antibiotic therapy. There was no longer any evidence of the PI-RADS 5 lesion by mpMRI six months after the treatment.

Conclusion: We reported that prostatic malakoplakia can present as prostatitis and a PI-RADS score 5 lesions. This awareness can prevent misdiagnosis and overtreatment of such a rare but benign condition. Combined surgical excision and antibiotic courses were effective in the treatment, and the importance of long-term follow-up of the patient is emphasized.

Keywords: Malakoplakia; Michaelis-Gutmann bodies; Prostate; Multiparametric magnetic resonance imaging