Multiparametric MRI appearances of primary granulomatous prostatitis.

Radiological features of granulomatous prostatitis (GP) overlap with those of prostate adenocarcinoma. Identification of specific GP features may aid diagnosis. We aimed to evaluate the multiparametric MRI (mpMRI) features of GP. We retrospectively reviewed 16 patients from a cohort undergoing mpMRI and transperineal sector-guided prostate biopsies between July 2012 and May 2017. Images were analysed for lesion location, shape, size, extracapsular extension, signal intensity (SI), apparent diffusion coefficient (ADC) values, dynamic contrast enhancement (DCE) pattern and PI-RADS (Prostate Imaging - Reporting and Data System) v2 score. Histology revealed 13 cases of nonspecific GP and 3 cases of xanthogranulomatous prostatitis. GP lesions were diffuse involving > 50% of the prostate ( GP is difficult to differentiate from prostate cancer, but typically gives diffuse changes involving > 50% of the gland on mpMRI, with extracapsular extension and rim-enhancing areas. It should be considered a differential diagnosis in patients with recent urinary tract infection (UTI) or prior Bacillus Calmette-Guerin (BCG) treatment. Prostate MRI imaging features including diffuse changes, extracapsular extension and rim-enhancing areas, in patients with recent UTI or BCG treatment may help identify granulomatous prostatitis cases.