Distinctive growth patterns between cerebral and cerebellar astrocytomas--a tissue culture study.

Astrocytomas have been alternatively considered as a single entity with topographical variabilities or as two different tumours--cerebral astrocytomas and mid line-cerebellar, astrocytomas. Twenty-two astrocytomas, 13 of the cerebral hemispheres, six cerebellar, two brain stem and one of spinal cord, have been studied by short-term tissue cultures. Two distinctive growth patterns have been found. Cerebral astrocytomas grew in the first week as radially arranged bipolar cells and subsequently by multipolar astrocytes in a reticular pattern. On the other hand, astrocytomas of the cerebellum, brain stem and spinal cord showed radial growth of long bipolar cells which persisted during the first 2-3 weeks. Only in the fourth week did a reticular pattern develop, but most of the cells remained bipolar. After the fourth week, a small number of multipolar astrocytes appeared and in two cases Rosenthal fibres were found. It is thus suggested that astrocytomas may be subdivided into two entities, those of the cerebral hemispheres and others in the cerebellum, optic nerve, brain stem and spinal cord which can be grouped as midline astrocytomas.