Melanotic schwannoma: a case with strong CD34 expression, with histogenetic implications.

Melanotic schwannomas (MS) are rare tumors composed of cells with both schwannian and melanocytic features, which usually occur in the setting of Carney's Complex. We describe a case of a 36-year-old male who presented with a mass that was attached to the vertebral body as well as the nerve roots of L2 and L3. Immunohistochemical positivity for S-100, HMB-45, and Pan-melanoma markers, as well as characteristic morphologic and ultrastructural findings, suggested that the lesion was a MS. The interest in this case lies in the fact that this case of MS showed strong CD34 expression, a marker that is generally negative in melanocytic tumors. We discuss the biologic significance of the high CD34 expression by the tumor cells and attempt to shed light on the histogenesis of this rare entity.