Robotic Surgery for Rare Pelvic Tumours: A Case of Retroperitoneal Schwannoma By Dr. Rubina Shanawaz

A 77-year-old woman came to Fortis Hospital, Bannerghatta Road, with complaints of right leg pain and a persistent limp. What initially appeared to be a possible gynecological condition turned out to be a rare pelvic schwannoma. With the help of robotic-assisted surgery, the tumour was safely removed, leading to significant improvement in her mobility and overall quality of life.

What is Schwannoma?

Schwannomas are benign tumours that develop from Schwann cells in the sheath of peripheral nerves. While they are most commonly seen in the head, neck, or limbs, their occurrence in the pelvis is rare. Because of their location and proximity to major nerves and vessels, pelvic schwannomas can be difficult to diagnose and treat. This case illustrates how robotic-assisted surgery can provide a safe and effective solution in complex pelvic surgeries.

Case Presentation

A 77-year-old obese woman presented with right leg pain and difficulty walking. She was evaluated with MRI of the spine for suspected nerve compression, which unexpectedly revealed a right-sided adnexal mass.

Clinical findings included:

• A 10 × 10 cm pelvic mass extending to the lateral wall
• Normal tumour markers
• Initial impression: possible adnexal malignancy

Given the complexity, robotic-assisted surgery with intraoperative frozen section was planned.

Intraoperative Findings

During surgery, both adnexa were found to be normal. Instead, a retroperitoneal mass was discovered in the right obturator space.

Key intraoperative observations:

• Encapsulated, solid-cystic, golden-yellow mass
• Located inferomedial to the external iliac vessels , displacing obturator nerve medially with levator ani muscle of the pelvic floor as it’s base
• Safely dissected and excised using robotic precision

Histopathology: Frozen section and final report confirmed the mass as a benign schwannoma.

Discussion

Schwannomas are slow-growing, encapsulated tumours. Pelvic schwannomas are rare and may mimic gynecological conditions, making diagnosis challenging. Symptoms depend on the tumour’s size and site, often presenting as pain, weakness, or a palpable mass. Malignant transformation is very uncommon.

Surgical excision is the standard treatment, but the location of pelvic schwannomas makes them technically demanding. In this case, the robotic platform offered magnification, stability, and precise dissection — allowing safe removal without injury to vital pelvic nerves or blood vessels of the lateral deep pelvic space. 

Outcome

The surgery was uneventful and followed the ERAS (Enhanced Recovery After Surgery) protocol. The patient was mobilised early and discharged on the first postoperative day. Notably, her preoperative limp resolved, and she was able to walk comfortably after surgery.

Conclusion

Pelvic schwannomas, though rare, should be considered in the differential diagnosis of pelvic masses. This case highlights how robotic-assisted surgery can play an important role in treating such tumours, enabling safe removal, faster recovery, and improved functional outcomes for patients.