Prognosis of the so-called "diffuse" cerebellar astrocytoma.

The term "diffuse cerebellar astrocytoma" was originally introduced by Russell and Rubinstein to describe that minority of cerebellar tumors microscopically similar to the cerebral hemispheric astrocytoma. The aim of this study was to verify some recent reports warning against the less favorable long term prognosis of the "diffuse" form of the cerebellar astrocytoma. We reviewed our series of cerebellar astrocytomas in children and collected 49 cases operated on before 1966 (i.e., with a follow-up ranging from a minimum of 15 years to 29 years). In addition, we reexamined all recurrent cerebellar astrocytomas observed during a 30-year period, looking for the eventual occurrence of the "diffuse" form. In the first group, 10 cases (20%) were classified as "diffuse" and 39 cases (80%) were classified as "classic". However, in 3 cases largely featuring a diffuse pattern, we also noted some areas of the classic type. These two subgroups showed no significant differences in patient sex and age, the incidence of macrocysts, the surgical technique used, the eventual x-ray therapy, and the long term functional results (P greater than 0.05). When we studied recurrent tumors that were reoperated on, we did not find any case showing histologically the "diffuse" pattern. To conclude, we cannot agree with the pessimism about the ominous long term prognosis of the diffuse cerebellar astrocytoma. In our opinion, the so-called diffuse cerebellar astrocytoma does not exist as a separate clinicopathological entity.