Prostatic Involvement in Granulomatosis with Polyangiitis: A Case Report and Scoping Review

Background and Clinical Significance: Granulomatosis with polyangiitis (GPA) is a systemic antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis that typically affects the respiratory tract and kidneys. Prostatic involvement is rare and may mimic infection or malignancy, delaying diagnosis. We report a case of exceptionally extensive urogenital destruction and provide a scoping review of prostatic involvement in GPA published since the last comprehensive review in 2019. Case Presentation: A 60-year-old man underwent repeated antibiotic courses and urological procedures for sterile, antibiotic-refractory prostatic and periurethral necrosis, initially attributed to infection or malignancy. Imaging showed a contiguous necrotising process extending from the prostatic fossa to the urethra, bladder trigone, penile base, and left upper urinary tract. With concurrent sinonasal and mastoid disease, karyorrhectic necrosis on histology, and low-titre ANCA positivity, GPA was diagnosed and treated with glucocorticoids and cyclophosphamide followed by rituximab, with regression of active disease but persistent structural sequelae. A PRISMA-ScR-guided search of PubMed, Scopus, Web of Science and Embase (24 August 2026) identified post-2019 reports of prostatic involvement in GPA. Fifteen publications plus the present case yielded 16 cases for structured extraction. Mean age at first prostatic manifestation was 55.1 years, and the mean reported interval to diagnosis was 4 months. Prostatic abscess was the most frequently reported imaging finding. PR3-ANCA positivity (13/16) and pulmonary involvement (13/16) were reported most often; renal involvement was reported in 4/16 cases and death in 4/16. Rituximab was reported more often than cyclophosphamide (10/16 vs. 7/16). Conclusions: Reports of prostatic involvement published from 2019 onward appear broadly consistent with the profile described in the last comprehensive review. These proportions, however, describe a small, publication-selected case series and are not estimates of the characteristics, prognosis or treatment response of prostatic involvement in GPA. Prostatic involvement may extend contiguously into the urethra, bladder, penile structures and upper urinary tract; the present case is one of the most extensive examples identified in this review. Sterile, antibiotic-refractory urogenital lesions, especially with extra-urogenital disease, low-titre or discordant ANCA serology, should prompt consideration of GPA before irreversible anatomical loss.