Malacoplakia of the prostate sonographically mimicking carcinoma.

Malacoplakia is an uncommon granulomatous inflammatory disorder that usually affects the urinary bladder and only rarely affects the prostate. Prostatic malacoplakia was detected in five patients by means of transrectal sonography and confirmed by means of ultrasound-directed transrectal biopsy. Hypoechoic peripheral zone lesions, which are suggestive of carcinoma, were found in all five patients, including two with capsular irregularity and one with a lobular prostatic contour suggesting stage C disease. The results of this study suggest that, with the increased use of sonographically directed transrectal biopsy, prostatic malacoplakia may be found to be more common than previously suspected.