[Peripheral nerve ectomesenchymoma (neuroectomesenchymoma): a malignant tumor made up of neural crest elements]

Characteristics of a little-studied tumor of soft tissues are described on the basis of the author's own material (4 observations) and data from the literature. The matter at issue is a benign or malignant schwannoma (less frequently, ganglioneuroblastoma) in which there are areas of rhabdomyosarcoma and sometimes tumor elements of mesenchymal origin (angio- lipo-, or osteogenic sarcoma). As a rule, this tumor is located along the peripheral nerve or arises in one of the nodes in Recklinghausen's disease and has a trend to hematogenic metastasising. It is suggested that the source of growth of neoplasias of this kind are the cells of "neural crest" migrating in the process of embryogenesis. These cells are responsible for the formation of lemmocytes, ganglial elements and melanocytes, as well as ectomesenchyma from which, in its turn, a part of cross-striated musculature is formed. Therefore, the tumors described in the paper should be designated as "neuroectomesenchymoma" (according to some authors, ectomesenchymoma).