胸鎖乳突筋に発生した増殖性筋炎の1例

A case of proliferative myositis of the left sternocleidmastoid muscle

Ⅰ．はじめに

　増殖性筋炎は横紋筋内に生じる良性の線維性増殖性疾患であるが，頭頸部領域での発生は比較的稀である^1,2）。臨床経過上では比較的急速に腫瘤を形成するため，悪性腫瘍との鑑別が重要となる。今回われわれは左胸鎖乳突筋に発生した増殖性筋炎の1例を経験したので，若干の文献的考察を加えて報告する。

　Although proliferative myositis（PM） is benign, the condition had been initially confused with a malignant disease because of its rapid growth. A 76-year-old female visited our hospital with the chief complaint of the left lateral neck swelling and tenderness. An elastic hard mass was palpable on that lesion. The skin color was slightly reddish and the border was unclear. Open biopsy was performed and the microscopic diagnosis was PM. The mass was disappeared with conservative treatment one month after the diagnosis. Clinical course was uneventful until now.