Seminal Vesicle Schwannoma: Transrectal and Intraoperative Sonographic Findings.

Schwannomas, namely neurilemmomas, are benign nerve sheath tumors and comprise the myelin sheaths around the peripheral nerves. Schwannomas commonly occur in the head and neck, or extremities, less found in the mediastinum and retroperitoneum, and rarely in the pelvis. We report a 40-year-old male presenting with an 18-month history of nocturia and urinary frequency. Transrectal ultrasound revealed a well-defined, 2.81 cm × 3.77 cm in size, homogeneous, hypoechoic mass in the tail of the left seminal vesicle, compatible with the finding of a well-demarcated mass at the left seminal vesicle with homogeneous contrast enhancement on computed tomography. He underwent laparoscopic excision of the mass via da Vinci robotic surgical system. Intraoperative sonography showed that the mass exhibited the majority of hypoechoic density with some hyperechoic spots inside. Pathology reveals schwannoma. Both of erectile and ejaculatory functions were claimed postoperatively. Our case report highlights the potential of either intraoperative or preoperative sonography in the assessment of the seminal vesicle schwannoma.