[An autopsy case of intravascular malignant lymphomatosis with intracranial lymphomatous mass lesions].

A 50-year-old man was admitted to our hospital, because of weakness in his right leg. On admission, he had generalized hyperreflexia and positive Babinski signs bilaterally. After admission, weakness in his left leg and confusion developed. A cerebrospinal fluid examination revealed increases in cell counts and protein but was negative for malignant cells. Blood chemistry was normal except for elevated LDH. A bone marrow biopsy yielded lymphoma cells. Successive T2-weighted cranial MRI showed a progressively expanding high signal area in the right parieto-occipital lobe. His confusional state improved after chemotherapy; however, two months later another cranial CT showed multiple enhanced mass lesions. The patient died 20 months after the onset of illness. Postmortem examination revealed widespread intravascular aggregates of malignant lymphomatous cells in the cerebrum, lungs and kidney, as well as multiple infarcts without atherosclerosis in the cerebrum. These pathological findings are compatible with those of intravascular malignant lymphomatosis. In addition, extravascularly expanding tumor cells formed multiple nodular lesions in the cerebral hemisphere. An immunohistochemical study showed that the tumor cells were positive for B-cell marker L26. Intracranial lymphomatous mass lesion rarely occurs in cases of intravascular malignant lymphomatosis. In the present case, tumor cells were presumably restricted to intravascular spaces, occluded them and resulted in ischemic lesions in the cerebrum in the early phase, but they expanded extravascularly and developed mass lesions in the terminal stages. In conclusion, intravascular malignant lymphomatosis is considered to be phenotypes of malignant lymphoma. This is the first case of intravascular malignant lymphomatosis associated with intracranial lymphomatous mass lesions in Japan.