Melanotic Schwannoma of the Mediastinum: Light and Electron Microscopic Study

Abstract

A case of a melanotic schwannoma of the mediastinum was studied by light and electron microscopy. Ultrastructurally the tumor cells were found to contain morphologically abnormal melanosomes. In addition, several peculiar, membranous, multi-chambered spheroids were seen arising from the plasma membrane of the tumor cells. The significance of these findings is briefly discussed. Melanotic schwannoma is a rare tumor, 23 cases of which have been reported in the literature. Only one of these occurred in the mediastinum.