Neurilemmoma of a seminal vesicle

Neurilemmoma, also named Schwannoma, is usually a benign tumour composed of Schwann cells.1,2 It is commonly located in the retroperitoneum, mediastinum, head and neck, and is rarely seen in the genitourinary organs. Only 2 cases of neurilemmoma originating from the seminal vesicle have been reported.3,4 Here we present the third case. CASE REPORT A 31 year old man complaining of haemospermia and irritable voiding during previous month was admitted to our hospital in August 2005. Digital rectal examination showed a rubbery mass in the area of right seminal vesicle. Transrectal ultrasound showed a 2.2 cm soft tissue mass in the right seminal vesicle. Enhanced noncontrast CT scan of the pelvis revealed a soft tissue mass involving the right seminal vesicle, and the attenuation was 17 HU. CT contrast enhanced scan showed high-density area in the middle of the seminal vesicle mass, and the attenuation was about 40 HU (Fig. 1). There was no evidence of local invasion on CT scan. The serum prostate specific antigen level was 0.7 ng/ml. Cystoscopy was negative. Transrectal, ultrasound guided biopsy of the mass was performed and the pathological testing revealed a neurilemmoma of the seminal vesicle.Fig. 1.: Computed tomography scan shows a soft tissue mass in the right seminal vesicle (arrow indicating high-density area in the middle of the seminal vesicle mass).Transperitoneal laparoscopic excision of the seminal vesicle neurilemmoma was performed with the patient under general anaesthesia. Three laparoscopic ports were used: a 10 mm port at the infraumbilicus, a 5 mm port in the middle 5 cm above the pubis and a 10 mm port two thirds of the way along the line from the umbilicus to the right anterior iliac crest. A transverse incision was made in the retrovesical peritoneum. The vas deferens was identified and was used as a guide to find the seminal vesicle. The occupying lesion was then exposed, clipped and transected without adjacent injury. The specimen was removed through the 10 mm port in the lower abdominal quadrant (Fig. 2).Fig. 2.: The cross section of specimen demonstrates a small yellow transparent structure.Total operative time was 110 minutes. There were no postoperative complications and hospital stay was 5 days. Histological examination of the excised tissue confirmed the diagnosis of neurilemmoma (Fig. 3). The patient has been asymptomatic and free of local recurrence for 9 months of followup.Fig. 3.: Histopathological examination shows lower cellular density of the tumour cells with loose plasma (Haematoxylin-eosin staining, original magnification×20).DISCUSSION Neurilemmoma is a benign peripheral nerve tumour composed of well differentiated Schwann cells.1–4 The tumour is most commonly found in young and middle aged adults and is typically found along peripheral nerves.4,5 Neurilemmomas arising from the seminal vesicle are extremely rare. Only two cases have been reported in the literature. In 2002, Iqbal et al3 described the first case in a 79-year-old man with a history of nocturia.3 Subsequently, Latchamsetty et al4 reported another one in a 48 year old man who presented with right lower quadrant abdominal pain. Neurilemmomas of seminal vesicle are usually asymptomatic until they have been found incidentally or become large and compress the surrounding tissues. Abdominopelvic or transrectal ultrasound is the most useful initial diagnostic tool. Computed tomography or magnetic resonance imaging can be performed to evaluate the location, size and extension of the tumours. However, the diagnosis of neurilemmoma is difficult because of nonspecific presentation and radiographic appearance. In addition to neurilemmoma, the differential diagnosis of seminal vesicle tumours includes papillary adenoma, cystadenoma, fibroma and leiomyoma.4 A biopsy may be needed for confirming the diagnosis before operation. Surgical resection is the curative treatment for seminal vesicle neurilemmoma. Open surgical procedures may be the treatment of choice. However, the seminal vesicles are difficult organs to access. Because of the deep location of the seminal vesicles in the retrovesical space, open surgical access necessarily involves a large incision and extensive bladder mobilization.6 Therefore, traditional open seminal vesiculectomy may be associated with significant postoperative morbidity, such as ureteral injury, rectal and bladder wall injury. Recent reports of laparoscopic management of seminal vesicle cystic lesions have demonstrated that the transperitoneal laparoscopic approach provides straightforward access and excellent visualization of the retrovesical seminal vesicles with minimal postoperative morbidity.6–8 The blood supply can be meticulously controlled and the seminal vesicles can be cleanly dissected free of the bladder and prostate without entering the bladder or rectum.6 The operative time of our patient who underwent laparoscopy was only 110 minutes. The patient had minimal postoperative pain and short hospitalization. From our experience and a review of the literature, we conclude that laparoscopy may be the optimal minimally invasive approach in the surgical treatment of seminal vesicle pathologic conditions.