[Neurological disturbances caused by intravascular lymphomatosis]

Intravascular malignant lymphomatosis (IML) is a relatively rare type of malignant lymphoma that is mostly caused by B-cell type neoplastic lymphocytes and rarely by T-cell and NL-cell type cells. B-cell type IML is currently considered to consist of 2 types: a conventional European type and an Asian variant that was originally reported from Japan. In IML, the tumor cells primarily grow within the blood vessel lumina but may cause minimal extravascular infiltration around the involved vessels in some patients. IML usually affects elderly patients and is characterized by B symptoms, general fatigue, disorders of various organs, and elevated serum lactate dehydrogenase (LDH) and soluble interleukin-2 receptor (sIL-2R) levels. Common symptoms include skin eruptions, neurological abnormalities, and gastrointestinal abnormalities. The skin changes and neurological symptoms are more frequent in the conventional type of IML but are not rare in the Asian variant. Neurological manifestations are primarily caused by varying degrees of ischemia due to intravascular tumor cells. These symptoms are usually subacute in onset and have a progressive course: They include, in the order of frequency, 1) multiple cerebral infarcts, 2) disorders of lumbosacral cord and its nerve roots accompanied by paraparesis, 3) subacute encephalopathy, and 4) mononeuropathy and multiple mononeuropathy that include cranial nerves. The most important diagnostic finding in IML is the histological demonstration of tumor cells within small vessel lumina. Although the antemortem diagnosis of IML has been difficult, the results of recent studies involving random skin biopsy are promising for such a diagnosis. Since the recent addition of rituximab to CHOP therapy has proven to markedly improve the prognosis of IML. We should therefore try to avoid overlooking this treatable disease.