肺コロイド腺癌の1例

A case of pulmonary colloid adenocarcinoma

コロイド腺癌は多量の粘液の中に腫瘍細胞が浮遊する特徴的な腺癌で，肺癌の中でその頻度は0.13％とされ非常にまれである。細胞外粘液が肺胞腔を破壊しながら進展していき，粘液の量に比して腫瘍細胞が少ないことから，生検での術前診断は困難とされる。画像所見では豊富な粘液貯留を反映した所見を呈し，肺内気管支原性嚢胞や粘液産生性腺癌の肺転移などが鑑別に挙がる。今回我々は，まれなコロイド腺癌の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。

We report a case of pulmonary colloid adenocarcinoma, an extremely rare malignant tumor of the lung. Chest computed tomography（CT）revealed a solitary mass with cystic features, showing contrast enhancement and abnormal uptake on fluorodeoxyglucose positron emission tomography（FDG-PET）at the peripheral region of the lesion. Two transbronchial biopsies were performed preoperatively, but both failed to yield a definitive diagnosis. Due to the progressive enlargement of the mass, surgical resection was undertaken. Postoperative histopathological examination confirmed the diagnosis of colloid adenocarcinoma. Although pulmonary colloid adenocarcinoma is exceedingly rare, it should be included in the differential diagnosis when an enlarging cystic lesion is observed in the lung.