肝様腺癌の成分を有する肺原発高悪性度胎児型腺癌

High-grade Fetal Lung Adenocarcinoma with Hepatoid Adenocarcinoma Component

高悪性度胎児型腺癌（H-FLAC）は全肺癌のうち0.4～0.7％1，2）の頻度で生じるまれな組織型である．また，肝細胞癌と類似した組織像を示す肝様腺癌もYangらの報告では41例（1981〜2017年）3）を認めるのみで，比較的まれな組織型である．われわれは，きわめてまれな肝様腺癌の成分を含むH-FLACの1例を経験したので報告する．

A 71-year-old man with a history of smoking 1 pack of cigarettes per day for the past 53 years visited our department with chest pain, and was diagnosed as spontaneous pneumothorax. A chest computed tomography scan revealed a nodular shadow in the upper portion of the left lobe of the lung, which was found to be adenocarcinoma by transbronchial lung biopsy. A left upper lobectomy and lymphadenectomy were performed. The pathological diagnosis was a high-grade fetal lung adenocarcinoma （H-FLAC） with a hepatoid adenocarcinoma component （pT2aN0M0, pStageⅠB）. H-FLAC comprises at least 50％ fetal lung-like cells, while hepatoid adenocarcinoma comprises hepatocellular carcinoma-like cells. Following the diagnosis, adjuvant chemotherapy with uracil-tegafur was started. Although both these neoplasms are known to have a poor prognosis, no recurrences were observed at 11 months postsurgery.