Granulomatous Prostatitis

Clinical History: In September 2011, a 76-year-old male presented for a routine multiparametric MRI to follow a Gleason 6 cancer as part of his Active Surveillance program. This cancer was proven by biopsy the previous year. Initial prostate imaging confirmed low-grade, low risk disease (Figure A, Figure B, Figure C).

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Figure A. T2-weighted axial image                                

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Figure B. Parametric overlay

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Figure C. Kinetic analysis

Imaging also revealed an incidental bladder polyp on the left  (Figure D, Figure E).  

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Figure D. Coronal T2-weighted image of the polyp

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Figure E. Axial T2-weighted image

The polyp was subsequently biopsied and proven to be bladder cancer for which he received treatment.

On routine digital rectal examination (DRE) follow up in May 2012, a nodular mass was appreciated in the left lobe of the prostate gland. Color Doppler showed increased blood flow and the patient’s PSA had increased.

Multiparametric MRI was performed and compared to the previous study in September 2011. Dramatic change was evident in the left peripheral zone (PZ) mid-gland to base with bulging of the capsule (Figure F, Figure G, Figure H) and positive spectroscopic findings.

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Figure F. Axial T2-weighted image                                  

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Figure G. Parametric overlay image

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Figure H. Kinetic analysis

Diagnosis: Biopsy showed prostatitis.

Discussion: Notably, this patient was treated with intravesical bacillus Calmette-Guérin (BCG) immunotherapy for his bladder tumor. This caused BCG-induced granulomatous prostatitis, nicely demonstrated as change from baseline.

References
1. Aust TR, Massey JA. Tubercular prostatic abscess as a complication of intravesical bacillus Calmette–Guérin immunotherapy. International Journal of Urology. 2005;12:920–921.
2. Lafontaine PD, Middleman BR, Graham SD, et al. Incidence of granulomatous prostatitis and acid-fast bacilli after intravesical BCG therapy. Urology. 1997;49:363–366.

Robert Princenthal, MD, Rolling Oaks Radiology, Thousand Oaks, CA