喉頭平滑筋肉腫の1例

A case of leiomyosarcoma of the larynx

I．はじめに

　喉頭原発の悪性腫瘍はほとんどが扁平上皮癌で，非上皮性腫瘍は約1％と少ない^1）。一方，非上皮性腫瘍のうち肉腫については，頭頸部領域では横紋筋肉腫が多くを占め，平滑筋肉腫は稀である^1）。平滑筋肉腫の診断は，臨床的にも組織学的にもほかの間葉系腫瘍との鑑別が困難であるとされているが，近年の免疫組織学的検査法の進歩によりその報告も徐々に増えつつある。しかし喉頭原発の平滑筋肉腫は本邦では十数例の報告があるのみで，治療方針も確立されていない。今回われわれは，喉頭に発生した平滑筋肉腫の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。

A 42-year-old man presented with a tumor of the larynx originated from the right vocal cord. The biopsy specimen was composed of long spindle-shaped cells with blunting nuclei. Immunohistochemical examinations showed that these cells were positive for anti-α-smooth muscle actin and vimentin,but negative for S-100 protein. This tumor was diagnosed as leiomyosarcoma by these findings. Vertical hemi-laryngectomy was performed. After three-year's follow-up,no recurrence has been noted. The incidence of leiomyosarcoma of head and neck is rare,although the number of case reports is increasing recently. Surgical resection is the first choice of therapy because the effectiveness of radiation therapy and chemotherapy is limited. Long-term follow up is necessary since local recurrence or distant metastasis is known.