Leptomeningeal dissemination of cerebellar malignant astrocytomas.

Primary malignant astrocytomas of the cerebellum are extremely rare, and the dissemination patterns and effectiveness of postoperative radiation therapy are unclear. Five consecutive cases of histologically proven cerebellar malignant astrocytoma, two anaplastic astrocytomas, one anaplastic pilocytic astrocytoma, and two glioblastomas, were treated between 1997 and 2001. Four patients underwent surgical removal, local irradiation, and chemotherapy, and one patient with anaplastic pilocytic astrocytoma received subtotal removal followed by gamma knife radiosurgery for the residual tumor. Two patients had no recurrence at the primary site. All patients developed leptomeningeal dissemination. Four patients had supratentorial dissemination and two patients had spinal metastases. The time interval between the diagnosis of the primary cerebellar tumor and the diagnosis of leptomeningeal dissemination was 5-29 months (mean 14.6 +/- 10.4 months). All patients died at 10-38 months (mean survival 22.2 +/- 13.6 months). Intensive treatment including chemotherapy and radiotherapy may be required in cerebellar malignant astrocytomas, considering the high incidence of symptomatic leptomeningeal dissemination.