Multiparametric MRI characterization of giant benign prostatic hyperplasia with an intraprostatic calculus: Operative and histopathologic correlation in a case report

Multiparametric MRI can characterize extreme prostatic enlargement, assess cancer suspicion, and define obstructive urinary tract changes. We describe radiologic and operative correlation in giant benign prostatic hyperplasia. MRI demonstrated a prostate measuring 12.0 × 8.5 × 10.1 cm, with an ellipsoid volume of 539.4 mL and grade III intravesical prostatic protrusion measuring 2.5 cm. The transition zone was replaced by well-circumscribed heterogeneous nodules, some with a nodule-in-nodule appearance. No focal suspicious diffusion abnormality or early enhancement was identified; the highest reported assessment category was PI-RADS v2.1 category 2. Findings also included bladder-wall thickening and trabeculation, a left anterolateral bladder diverticulum, mild bilateral upper urinary tract dilatation, and a solitary 2.07 × 2.11 × 1.99 cm right anterior transition-zone focus. The focus was markedly T2 hypointense, intermediate on T1-weighted and STIR images, hypointense on b = 1400 s/mm² DWI, hyperintense on the ADC map, and nonenhancing, indicating facilitated diffusion. The 60-year-old patient had catheter-dependent urinary retention and prostate-specific antigen of 98 ng/mL. Systematic biopsy showed benign prostatic hyperplasia with chronic inflammation. Open transvesical prostatectomy with diverticulectomy yielded a 510 g adenoma and an approximately 2 × 2 × 2 cm calculus at the corresponding location. Representative prostatectomy sections showed nodular glandular and stromal hyperplasia without identified carcinoma. At 18 months, symptoms, postvoid residual urine, and prostate-specific antigen improved, with preserved continence and resolved upper urinary tract dilatation. MRI localized and characterized the focus but could not prospectively determine its composition; operative correlation established the diagnosis.