神経皮膚黒色症と鑑別を要した巨大色素性有毛性母斑と星細胞腫が合併した稀な1例

A Rare Case of Diffuse Astrocytoma Complicated with Giant Pigmented Hairy Nevi,Suspected Neurocutaneous Melanosis

Ⅰ．はじめに

　神経皮膚黒色症（neurocutaneous melanosis）は全身性に先天性巨大色素性有毛性母斑（congenital giant pigmented hairy nevi）あるいは獣皮様母斑を呈し，脳軟膜や実質におけるメラニン色素増殖部位および皮膚母斑部位から悪性黒色腫（malignant melanoma）を生ずる可能性がある稀な疾患である．今回，神経皮膚黒色症が疑われた先天性巨大色素性有毛性母斑を有する6歳女児において頭蓋内星細胞腫を合併した1例を経験した．巨大色素性有毛性母斑，星細胞腫瘍の合併例はこれまで報告がなく極めて稀であるが，神経皮膚黒色症における脳軟膜および脳実質原発悪性黒色腫と予後は大きく異なり星細胞腫は外科治療を含めた集学的治療対象となり得るため，両者の鑑別は非常に重要である．画像上の差異を含め過去の文献を踏まえ報告する．

　A 1-year-old female infant presented with congenital giant, hairy and pigmented nevi. MRI scan as screening test revealed a cerebellar tumor. A diagnosis of provisional neurocutaneous melanosis was made on the basis of the patient's MRI and physical findings. At her 6 years of age, MRI revealed the tumor grown up to 3 cm diameter in 5 years. The cerebellar tumor was removed partially using the occipital transtentorial approach for tissue diagnosis. The color of the cerebellar tumor was whitish and contained neither benign nor malignant melanocyte. Pathological examination revealed diffuse astrocytoma. Finally residual cerebellar tumor was totally removed at a second surgical resection. To our knowledge, this is the first patient to be reported with astrocytoma complicated giant skin nevus except neurocutaneous syndrome cases.