Malakoplakia of the prostate masquerading as locally advanced prostate cancer on mpMRI

Abstract

A 66-year-old man was referred for urological evaluation for an abnormal digital rectal exam (cT2a, subtle nodule at left base, 121 cc prostate) and an elevated prostate specific antigen (PSA) of 8.0 ng/ml. Subsequent 12-core transrectal ultrasound (TRUS)-guided biopsy revealed Gleason 3+4 adenocarcinoma in seven of 12 cores, including all six cores on the right side and one core at the left apex. No extraprostatic extension was identified. Post-biopsy, the patient developed urinary retention requiring a catheter, as well as an Escherichia coli (E. coli) urinary tract infection (UTI) requiring hospitalization and intravenous antibiotics.

Fig. 1.

Axial T2 (upper left), ADC map (upper right) and DWI (lower left) slices from 3T-multiparametric MRI demonstrating a mass with restricted diffusion (arrows) from the left mid-gland of the prostate extending beyond the capsule to the rectum, with loss of the intervening fat plane. An image from the dynamic contrast enhancement series (bottom right) demonstrates hypervascular enhancement of the lesion (arrow).

Fig. 2.

Typical histological features of malakoplakia, including Michaelis-Gutmann bodies within prostatic histiocytes (left). The low-power view (right) demonstrates malakoplakia inflammation (❉), normal prostatic capsule (⨀), and adenocarcinoma (♦).