抄録
We encountered with a case of spontaneously occurring malignant cystic schwannoma on the intracranial trigeminal nerve in a rat (32-week-old male Crj:Wistar). The tumor was intermixtures of the solid and cystic areas. The solid area was densely cellular, and pleomorphic spindle-shaped cells with elongated bizarre nuclei, and mitoses were present. The cystic area was less cellular, and cells with less cytoplasm were sporadically present in the area. Morphologically and immunohistochemically (staining with S-100), the solid and cystic areas were considered typical Antoni type A and B, respectively. Taken together, the results indicate that the tumor is a spontaneous malignant cystic schwannoma. In this connection, most cells lining the cysts were positive for S-100 and negative for Factor VIII, while HE staining showed that degenerative vessels were absent in the tumor. Therefore, in this case, we assumed that the origin of the cysts was not from the vessel but from the tumor per se.
