Isolated melanotic schwannoma

Definition

A rare nervous system tumor characterized by cells phenotypically representing Schwann cells but containing melanosomes and expressing melanoma markers. The entity occurs as a non-psammomatous (typically affecting spinal nerves) or a psammomatous (also involving nerves of the intestinal tract and heart) variant. About 50% of psammomatous tumors are associated with Carney complex. Slightly over 10% of melanotic schwannomas follow a malignant course.