脳原発の悪性黒色腫の1例—特徴的なMRI所見について

A Case of Primary Intracranial Malignant Melanoma with Characteristic Magnetic Resonance Imaging

I．はじめに

　中枢神経系に原発する悪性黒色腫は，1987年の脳腫瘍全国集計調査報告^17）によると，全脳腫瘍の0.07％を占めるにすぎない．

　最近著者らは，脳軟膜に原発したと思われる悪性黒色腫の1例を経験したが、MRIにおいて腫瘍の一部がT₁強調像で高信号域を，T₂強調像で低信号域を呈していた．他の脳腫瘍と異なるこの特徴的なMRI所見について報告するとともに，その発現機序についても若干の文献的考察を加えた．

The authors reported a rare case of primary malig-nant melanoma in the central nervous system and dis-cussed the findings of MRI.

A 60-year-old male was admitted for examinations to discover the cause of his generalized tonic convulsions. On admissin, he had neither neurological deficits, nor were there any abnormalities revealed during physical examination. Ct scan disclosed a slightly high-density mass with perifocal edema in the right parietal cortex which enhanced markedly after injection of contrast material.