Surgical management of melanotic schwannomas: a 28-year mayo clinic experience and comparative literature analysis

Introduction: Melanocytic schwannoma is a rare nerve sheath tumor characterised by neoplastic melanin-producing Schwann cells. We present our institution's experience treating spinal melanotic schwannomas and compare it to the literature.

Methods: Data were collected for eight patients treated surgically for spinal melanotic schwannomas between 1996 and 2022 at all Mayo Clinic locations and 63 patients in the literature. Time-to-event analysis showing the risk of metastasis, recurrence, and death by tumor location and type of treatment received was created for all 71 cases combined. Unpaired two-sample t-tests and Fisher's exact tests assessed statistical significance between groups.

Results: Our hospital operated on eight melanotic spinal schwannomas between 1996 and 2022, while the literature cited 63. Like those in the literature, our patients were 43 at diagnosis.
The literature reported 16 instances, 23 recurrences, and 13 fatalities, while our institution had 2 metastatic cases, 5 long-term recurrences, and 5 deaths. All 71 patients showed higher postoperative metastasis rates after GTR, STR, or GTR plus radiation (p < 0.005). The highest postoperative recurrence rate was observed following GTR, followed by STR, STR with radiation, and GTR (p < 0.005). GTR alone, STR with radiation, and GTR with radiation and STR alone resulted in death (p < 0.005). Nerve root melanotic schwannomas had a higher metastasis and death rate after surgery but a lower recurrence rate than intradural ones.

Conclusion : Sacral or presacral schwannomas' outcomes depend on demographics, tumor features, symptoms, and surgery. Pain dominates these patients' symptoms. Patients treated with GTR plus radiation had the lowest postoperative metastasis and recurrence, while those treated with STR alone had the highest survival. Nerve root melanotic schwannomas exhibited higher postoperative metastasis and death but lower recurrence than intradural ones.