[MR spectroscopy findings of a case of intravascular malignant lymphoma: usefulness for differential diagnosis].

We report a 49-year-old previously healthy woman with acute onset of decrease in attention, dysarthria and ataxia, accompanied by drowsiness. On admission, there were cloudness of consciousness, hallucination and left hemiparesis. Cerebrospinal fluid study revealed a cell count of 1/mm3, and the cytology was class I with a slight increase in protein. MRI of the brain performed on admission showed multiple gadolinium-enhanced lesions with a T2 weighted high intensity area in the cerebral white matter. At first the patient was diagnosed as acute disseminated encephalomyelitis (ADEM), and treated with methylprednisolon pulse therapy. Soon after, she showed transient clinical improvement, but her condition soon worsened. MR spectroscopy revealed elevated choline peak, decreased NAA peak and lactate peak, which indicated a neoplastic lesion. The brain biopsy disclosed diffuse intravascular lymphoma (IVL). MRS was useful in the differential diagnosis of IVL from ADEM.