[Granular cell tumor and the phagocytozing form of Schwann cells. Electron microscopic examinations of 3 cases (author's transl)].

In granular cell tumors, the granule-containing tumor cells and their processes form rounded complexes surrounded by a common bounding membrane. In the tumor, these complexes are closely related to the peripheral nerves and are seen in the perineurium and in the endoneurium. In addition, there are mixed complexes composed both of Schwann cells and granular tumor cells: the two types of cells are in close contact with each other and are also surrounded by a common bounding membrane. Furthermore, there one contacts between granular tumor cells and axons. These observations strongly suggest the existence of a relationship between Schwann cells and the cells of granular cell tumors. A comparison between the granular tumor cells and the phagocytic forms of Schwann cells reveals striking similarities: the granular cell tumor complexes are comparable with the Büngner bands of phagocytozing Schwann cells. A relationship between granular cell tumors and the phagocytozing form of Schwann cells is therefore assumed.