[Mono-radiculopathy multiplex--multiple infarction of the cauda equina caused by intravascular lymphomatosis].

A 55-year-old man had felt numbness of the bilateral peroneal sides of legs for 6 months. Then hepatosplenomegaly, anemia, body weight loss and fever developed, and a diagnosis of malignant histiocytosis (MH) was made by revealing the presence of innumerable atypical histiocytes with hemophagocytosis in the bone marrow. Soon later, sensory disturbance of bilateral peroneal sides of legs (right side dominant) developed and aggravated with painful dysesthesia and weakness of the legs for the last 2 weeks before death. Electrophysiologically, sensory conduction velocity of the sural nerve was normal and somatosensory evoked potentials from tibial nerve were normal before P15 but were not evoked at all after the lumbar potential, suggesting lumbosacral radiculopathy. Autopsy showed multifocal ischemic lesions and secondary degeneration of the lumbosacral nerve roots associated with necrosis and fibrosis of the radicular vessels and intravascular infiltration of atypical mononuclear cells which were positive for B cell markers. The neurological manifestations and the distribution of ischemic lesions, which were similar to those of vasculopathic mononeuropathy multiplex, would deserve the name of "monoradiculopathy multiplex".