筋肉内転移で発見された腎細胞癌

RENAL CELL CARCINOMA DETECTED BY METASTASIS TO THE SKELETAL MUSCLE

　45歳，男性。4か月前，右上腕の腫瘤に気づいたが，疼痛がないので放置していた。その後検査を希望し，当院整形外科を受診。悪性が疑われ摘出術を施行，組織学的に腎細胞癌の筋肉内転移と診断された。腎細胞癌の筋肉内転移はきわめて稀で，これまでに本邦で2例の報告がある。

We reported a case of renal cell carcinoma detected by metastasis to the skeletal muscle found in 45-year-old man. He has noticed a painless mass in the right upper arm 4 months before. He visited our department for evaluation of the mass. Histological examination revealed the mass to be skeletal muscle metastasis of renal origin. This is extremely rare, and to the best of our knowledge, the third reported case in the Japanese literature.