Dermal nerve sheath myxoma. A light and electron microscopic, histochemical and immunohistochemical study.

Two cases of dermal nerve sheath myxoma have been examined by light and electron microscopy, and by immunohistochemical and histochemical methods. The nomenclature of this tumor has been debated, and the histogenesis unsettled. Light microscopically, the lobulated myxoid tumors were generally composed of spindle-shaped and stellate tumor cells in an abundant matrix of mucosubstances. Ultrastructural features indicated an origin from the peripheral nerve sheath; among the pertinent findings were a single or duplicated external lamina investing the cells, desmosome-like junctions, cytoplasmic microfilaments and myelin figures, and interdigitating cytoplasmic processes. S-100 protein was demonstrated by means of the immunoperoxidase technique within both tumors, further supporting this origin. The histochemical analysis of the mucosubstance showed the presence of sulphated glucosaminoglycans. The name dermal nerve sheath myxoma, suggested by Harkin and Reed, is recommended.