Surgical management of sporadic and schwannomatosis-associated pelvic schwannomas.

Pelvic schwannomas are rare tumors that may occur either sporadically or in the context of schwannomatosis. We retrospectively reviewed the charts of patients harboring a pelvic schwannoma under conservative management or operated at our reference center between 2016 and 2023. All patients were operated by a multidisciplinary team, combining a vascular surgeon and a neurosurgeon. Twenty-four patients harboring 33 pelvic tumors were included in the cohort, including 12 patients with sporadic lesions, 2 patients with NF2-related schwannomatosis, and 10 patients with NF2-independent schwannomatosis. Multi-nodular tumors were more frequent in schwannomatosis compared to sporadic cases (p = 0.005). The mean age at diagnosis was 41 years old. Schwannomas were located on branches of the sciatic nerve (23/33, 70%), the femoral nerve (6/33, 18%), and the obturator nerve (4/33, 12%). Over the course of the study, 16 patients were operated, including 11 sporadic cases. The indication for surgery was pain (12/16, 75%) or tumor growth (4/16, 25%). Complete resection was achieved in 14 of 16 patients (87%). The mean post-operative follow-up was 37 months (range: 2-168 months). At last-follow-up, complete pain relief was achieved in all 12 patients with pre-operative pain. Post-operative morbidity included 3 long-term localized numbness and one MRC class 4 motor deficit in a multi-nodular tumor in a schwannomatosis patient. Despite its limited size, our series suggests that nerve-sparing resection of pelvic schwannomas offers satisfying rates of functional outcome both in sporadic and schwannomatosis cases, except for multi-nodular tumors.