Intracranial malignant lymphomas: clinicopathological study of 26 autopsy cases.

We examined 26 autopsy-proven cases of intracranial malignant lymphoma (IML) in immunocompetent patients to determine the extent of neoplastic involvement of the central nervous system (CNS) and to evaluate the effects of radiation on the tumor and brain tissue. All tumors were identified as diffuse non-Hodgkin's lymphomas of B-cell origin. In six patients who had not received radiotherapy, the clinical course of the disease was short and extensive infiltration of the tumor was seen. The remaining 20 patients were treated with radiotherapy and had a longer survival time. Leptomeningeal involvement was common, but extensive subarachnoid proliferation of the tumor was seen in only two cases. The posterior, but not anterior, lobe of the pituitary was involved in 5 of 22 cases, and choroid plexus involvement was seen in 4 of 21. Direct invasion of the tumor into the spinal cord, which tended to occur in patients with posterior fossa masses, was observed in 5 of 21 cases. Following irradiation, coagulation necrosis was frequently found in the invading zone as well as in the tumor mass, and degeneration of the white matter was also seen. We suggest that IML can extensively infiltrate into the CNS, including the posterior lobe of the pituitary and spinal cord, and that radiation injury to the brain appears to occur relatively easily in this disease.