[Lymphomatoid granulomatosis of the brain with multiple lesions on MRI].

A 28-year-old man was admitted to our hospital, because of double vision, memory disturbance and dysarthria. These symptoms developed in November, 1994. His mental activity was gradually decreased and he became apathetic. A physical examination on admission was unremarkable. There were no lymphadenopathy, hepatosplenomegaly or skin rash. Neurological examination revealed disorientation, decreased mental activity and left gaze-evoked nystagmus. Neuropsychological tests demonstrated impairment of recent memory and performance but frontal lobe functions were maintained. Laboratory data showed hyponatremia, elevation of antinuclear antibodies and IgG-antibodies to Epstein-Barr virus capsid antigen and Epstein-Barr virus nuclear antigen. A brain MRI revealed multiple lesions in the cerebral subcortex, cerebellum and brainstem. These lesions showed high signal intensity on T2-weighted images and enhanced high signal intensity on T1-weighted images using Gd-DTPA injection. A cystic mass was seen between bilateral lateral ventricles and contacted with the fornix and thalamus. Lymphomatoid granulomatosis was diagnosed by an open brain biopsy, which showed diffuse infiltration of small lymphocytes, histiocytes and plasma cells, especially around the small vessels. Epithelioid granuloma or necrosis was not seen. An immunohistochemical study showed that nearly all lymphocytes were MT-1 positive T lymphocytes. The patient was treated by whole brain irradiation (30Gy) and pulse therapy of methylprednisolone. Multiple lesions in the brain responded to these modalities with complete resolution of the lesions and clinical improvement. In this case, impressive multiple and cystic lesions seen on brain MRI disappeared by whole brain irradiation and steroid. Since etiologies of multiple lesions on MRI includes many possibilities, histological diagnostic methods should be performed to obtain a definitive diagnosis. This is the first case of lymphomatoid granulomatosis that showed multiple and cystic lesions on brain MRI in Japan.