Intravascular lymphomatosis.

Intravascular lymphomatosis, also known as endovascular lymphoma or angiotropic large cell lymphoma, is a rare malignancy typically diagnosed at autopsy. We describe a case in which the diagnosis was made at an early stage. Specific electrodiagnostic findings suggested concomitant polyneuropathy and myopathy. Suspicion of a paraneoplastic syndrome during electrodiagnostic testing prompted muscle biopsy, which revealed myopathy due to the direct infiltration of neoplastic cells. Resultant treatment with a standard chemotherapy regimen not only increased the patient's survival, but also improved neurological function.