Periprostatic Solitary Fibrous Tumor Mimicking Prostatic Mass: A Case Report

Solitary fibrous tumors (SFTs) are rare mesenchymal neoplasms commonly arising from the pleura, but can occasionally occur in extrapleural sites, including the pelvis. Periprostatic SFTs are exceptionally rare and may mimic prostatic masses on imaging and clinical examination, leading to diagnostic confusion. We report a case of a 60-year-old male presenting with acute urinary retention and a history of lower urinary tract symptoms. Imaging revealed a large pelvic mass displacing the bladder and effacing fat planes with the prostate. A transrectal ultrasound-guided biopsy suggested a spindle cell tumor, and immunohistochemistry (IHC) confirmed the diagnosis of SFT with diffuse STAT6 positivity. The patient underwent cystoprostatectomy with ileal conduit diversion. Intraoperative findings revealed a mass inseparable from the prostate and bladder. Histology showed a mitotic index of 9/10 high-power fields, consistent with a potentially malignant SFT. Postoperative recovery was uneventful, and follow-up imaging showed no recurrence. Periprostatic SFTs are exceedingly rare and can mimic prostatic neoplasms. Diagnosis requires integration of imaging, histology, and STAT6 IHC. Radical surgical resection remains the cornerstone of treatment, especially in large or potentially malignant tumors. Long-term follow-up is warranted due to recurrence risk.