Isolated schwannoma of the urinary bladder: a case report and review of the literature

Diagnostic accuracy of multiparametric ultrasound for peripheral nerve schwannoma

BACKGROUND

Ultrasound (US) diagnostic techniques have the advantages of low cost, convenient operation, and high availability.

PURPOSE

To explore the diagnostic accuracy of multiparametric US in evaluating signs of peripheral schwannoma.

MATERIAL AND METHODS

This retrospective case-control study included patients with soft-tissue masses on the limbs (divided into the schwannoma and non-schwannoma groups) between January 2017 and November 2020. US features were compared between the two groups, and receiver operating characteristics analysis was used to evaluate the diagnostic efficacy of these features.

RESULTS

A total of 165 patients were included in this study; of them, 63 (38.2%) were diagnosed with schwannoma. Regular morphology (95.2% vs. 39.2%), cystic degeneration (71.4% vs. 27.5%), target sign on elastography (82.5% vs. 0), and polar blood supply sign (87.3% vs. 14.7%) were more common in schwannomas than in non-schwannoma lesions (all P < 0.001). Combining the four signs for diagnosis of schwannomas, the sensitivity, specificity, and accuracy were 95.24%, 96.08%, and 95.76%, respectively, with an area under the curve (AUC) of 0.987 (95% confidence interval = 0.955-0.998). Entering and exiting nerve sign was observed in 87.3% of schwannomas and in 3.0% of non-schwannoma lesions (P < 0.001), while split-fat sign was similar between the two groups (9.5% vs. 2.0%; P = 0.068).

CONCLUSION

Polar blood supply sign and target sign on elastography are specific US signs in peripheral schwannomas. The combination of two-dimensional imaging, color flow imaging, and elastography can achieve an excellent diagnostic accuracy in schwannomas.

Laparoscopic partial cystectomy through extraperitoneal space for primary bladder schwannoma

BACKGROUND

Schwannomas can occur in the body where nerve sheaths are present. Genitourinary schwannomas are very rare, especially primary bladder schwannomas. They account for only 0.1% of bladder tumours. The literature reports that simple surgical resection has a good effect and prognosis.

CASE PRESENTATION

A 39-year-old man had no significant improvement in symptoms due to frequent urination and urgency for 1 month following the treatment of prostatitis for 2 weeks. Ultrasound and computed tomography (CT) showed a mass in the left side wall of the bladder (size approximately 2.0 × 1.9 cm) that had clear boundaries and protruded outward from the bladder. After the extraperitoneal space was dilated with a balloon, a minimally invasive laparoscopic partial cystectomy was performed in this space to remove the tumour. The pathological diagnosis was bladder schwannoma. Immunohistochemical staining showed that it was strongly S100 protein positive. There was no recurrence after 2 years follow-up by cystoscopy and CT.

CONCLUSIONS

Bladder schwannomas are clinically rare benign bladder lesions and no specific clinical manifestations. Laparoscopic partial cystectomy through the extraperitoneal space is a safe and feasible treatment option.