Malignant monstrocellular brain tumours. A study of 42 surgically treated cases.

A series of 42 cases of monstrocellular brain tumour (MBT) who received surgery over a 34 year period is reviewed with the aim of gaining more understanding of the biology of this oncotype. A case of benign pleomorphic xanthoastrocytoma was identified among the cases and is discussed in another paper. In this series, as in most others taken from the literature, MBTs were more frequent in young subjects (55% were under 50 years of age and 17% were children) and presented as a superficially located (63%), often sharply circumscribed (42%) mass. The mean survival time for 24 patients treated by surgery and radiotherapy (RT) was 57 weeks compared to 32 weeks for 12 treated by surgery alone (p less than 0.02). Patients younger and older than 50 years showed the same survival and the slightly better course of children did not reach statistical significance. Besides postoperative RT, the only other factor that showed a significantly positive influence on survival was the presence of a definite lymphocytic infiltration (LI) in the tumour (p less than 0.05). This result confirms our previous study on the prognostic influence of LI in glioblastoma (GB). Actually, we noted that the prolonged survival of both MBT and GB patients exhibiting a definite LI (67% and 11.5%, respectively, in the two series) was strikingly similar. We conclude that MBT is a peculiar oncotype with a probably better prognosis than GB in the majority of cases. Lymphocytes seem to play a major prognostic role and giant-monstrous cells are indirectly implicated, reasonably enhancing the host's immune response by magnifying the antigenic stimulus.