Melanotic schwannoma with drop metastases to the caudal spine and high expression of CD117 (c-kit)

Abstract

Melanotic schwannomas (MS) are tumors of Schwann cell origin characterized by cytoplasmic deposition of melanin. The authors present the case of a 61-year-old man who experienced progressive weakness of the lower extremities over 2 years. This was followed by acute deterioration, which prompted his presentation. MRI of the spine revealed an intradural, extramedullary lesion at the level of T7 with severe spinal cord compression. More caudally, there was involvement of the lumbar spine with drop metastases to the conus medullaris and cauda equina. The patient underwent thoracic laminectomy for tumor resection. A diagnosis of MS was made based on histologic morphology, immunohistochemical profile, and ultrastructural findings. In this report, the authors describe a MS with expression of CD117 (c-kit) and review the literature pertaining to this condition.