肺原発平滑筋肉腫の1例

Surgical Case of the Primary Pulmonary Leiomyosarcoma：Report of a Case

はじめに　肺原発平滑筋肉腫は，肺原発悪性腫瘍のうち0.5％程度にすぎないまれな腫瘍である．われわれは，肺原発平滑筋肉腫の1切除例を経験したので報告する．

A 70-year-old man was referred for an abnormal chest shadow. Enhanced computed tomography （CT） revealed a well-circumscribed lung tumor of 53 mm in diameter in the left upper lobe with slight enhancement. Positron emission tomography-CT showed a high maximum standardized uptake value for the tumor but no metastasis in the lymph nodes or other organs. Although a definitive diagnosis could not be made by transbronchial biopsy, the tumor was highly suspected to be malignant based on the radiological findings, and a left upper lobectomy with mediastinal lymph nodes dissection was performed for definitive diagnosis and treatment. A pathological examination showed the tumor to be composed of mitotic spindle-shaped cells, which were positive for α-smooth muscle actin, desmin, and caldesmon. The MIB-1 labelling index was 60～70％．According to these pathologic findings, the tumor was identified as a leiomyosarcoma. Metastases to the skin of chest and hilar lymph nodes were noted six months after the surgery for which radiotherapy was performed.