腺様嚢胞癌肺転移の画像所見

Radiologic findings of lung metastases from adenoid cystic carcinoma

腺様嚢胞癌（adenoid cystic carcinoma：ACC）は筋上皮細胞をもつ外分泌腺から発生する低悪性度腫瘍であり，頭頸部に発生することが多いとされている。比較的緩徐な増大速度のため，短期的な予後は良好であるが，神経周囲浸潤を伴った局所での再発や，肺および骨をはじめとする遠隔転移が高率に出現し，長期的な予後は不良との報告がある^1-8）。また肺原発のACCは，多くは中枢気管支発生で，末梢性のものは肺原発ACCの10％程度とされている^9）。

Adenoid cystic carcinoma（ACC）is a low-grade tumor originating from exocrine glands with myoepithelial cells, most commonly in the head and neck. The short-term prognosis is good due to its relatively slow growth rate. But the long-term prognosis is poor, because of local recurrence with perineural invasion and of distant metastases of lung and bone^1-8）. Although primary pulmonary ACCs have almost the origin in central bronchus, the cases of ACCs in peripheral lung were often reported^9）, and it led to argument where the ACCs were primary or metastatic lung tumors.

Because of the slow growth of pulmonary metastases, they may be misdiagnosed as benign lesions and treatment for the patients with ACC may be delayed. Even if the nodule may be resected, the histopathological diagnosis of primary pulmonary ACC may interfere with postoperative management.

We reviewed the imaging findings of metastatic pulmonary ACCs of four patients who underwent surgical resection at our institution and compared them to metastatic pulmonary tumors of other histologic types.