Oncology - Prostate
Introduction & Objective :
Granulomatous prostatitis (GP) secondary to Bacillus Calmette-Guerin (BCG) exposure is a well-described clinical entity. Influence of previous BCG exposure on imaging findings in patients undergoing multiparametric Magnetic Resonance Imaging (mpMRI) for detection and management of prostate cancer is poorly understood. As such, we describe a cohort of patients with previous BCG exposure who underwent US/MRI fusion biopsy at our institution.
We reviewed our prospective database containing patients who underwent US/MRI fusion biopsy (n=444) and identified men with prior intravesical BCG exposure. We then reviewed mpMRI results and subsequent fusion prostate biopsy findings.
Ten men treated with BCG who were found to have PIRADS 4 or 5 lesions on mpMRI and underwent fusion biopsy were identified (Table 1). Men who were biopsy naïve (30%), had history of previous negative biopsy (30%) and who were on Active Surveillance for low risk prostate cancer (40%) were included. The cohort was a median 64 (IQR 59-69) years of age and had median PSA of 6.3 (IQR 4.5-9.2). 80% of patients demonstrated biopsy-proven granulomatous prostatitis (GP). Pathology revealed clinically significant (Gleason Grade Group (GG Group) ≥ 2) prostate cancer in 3 patients (30%) with 1 additional patient (10%) harboring GG Group=1 disease. Targeted biopsy of MRI abnormalities revealed significant cancer in 20% of cases, with 90% demonstrating GP. Previously-described “Actionable Intelligence Metric” (AIM) was 0% for this cohort (i.e. targeted cores did not provide additional information over information from the 12-core template).
In this largest series to date, we show that although high risk lesions on mpMRI in patients with previous exposure to intravesical BCG likely represent GP, clinically significant prostate cancer may be present and is radiographically indistinguishable from granulomas. These limited data question the clinical utility of mpMRI in patients who have received intravesical BCG.