Local and diffuse spread of juvenile cerebellar astrocytomas in subarachnoid space. Light and electron microscopic study.

Based on 5 cases of juvenile astrocytomas the unusual behaviour of this type of tumor is described. It is expressed by local and/or diffuse spread of the neoplasms in the subarachnoid space of the brain hemispheres, cerebellum and spinal cord. The light and electron microscopic examinations have revealed the morphological features of well differentiated tumors of astrocytic origin and of fibrillary type which in a great number of cases have a favourable prognosis. The cause of break through into the subarachnoid space, despite its morphology which indicates on a high degree of differentiation of the tumors, is not known. The relation of primary to secondary infiltration of the subarachnoid space or of the leptomeninges is discussed.