腹水中のシフラ21-1が高値を示した肺腺癌の腹膜播種の1例

Elevated CYFRA 21-1 Level in Ascites associated with Pulmonary Adenocarcinoma

要旨　患者は61歳，男性．左背部痛を主訴に当科外来を受診．胸部Ｘ線写真で左胸水を認めたため入院し，肺腺癌と診断された．胸膜癒着術後，全身化学療法を施行されたが奏効しなかった．可溶性のサイトケラチン19フラグメントである血清シフラ21-1は治療開始前から17.7ng/mlと高値であり，徐々に上昇した．診断から9カ月後に大量の腹水が出現し，腹水中から腺癌細胞を認めた．シフラ21-1は血清(237.0ng/ml)，腹水(458.0ng/ml)ともに著明高値であった．剖検では腹膜播種を認め，サイトケラチン19の免疫染色を施行したところ，原発巣，腹膜播種巣ともに濃染を認めた．肺癌の腹膜転移は稀ではないものの，大量腹水を来すものは少ない．また，胸水中のシフラ21-1は非小細胞癌による悪性胸水の鑑別に有用とされているが，今回の経験から腹水中のシフラ21-1についても同様の診断的意義がある可能性が示唆された．

Summary

　A 61-year-old man was admitted to our hospital because of pleural effusion. Upon diagnosis of adenocarcinoma, he was treated with chemotherapy and cranial radiation for a brain metastasis. He was readmitted due to massive ascites nine months after the initial diagnosis. Adenocarcinoma cells were detected in his peritoneal fluid, and the CYFRA 21-1 level was increased in both serum and peritoneal fluid. The autopsy revealed primary pulmonary adenocarcinoma with peritoneal dissemination. Immunohistochemical staining of the autopsy specimens revealed that carcinoma cells were intensely positive for cytokeratin 19 in both the lung and peritoneum. Although metastatic involvement of the peritoneum is not a very rare autopsy finding, massive ascites caused by metastases of lung cancer has been rarely reported. CYFRA 21-1 assay of pleural fluid has been shown to be useful for discriminating malignant from benign pleural effusion, especially in patients with non-small cell lung cancer. We thought that the CYFRA 21-1 assay of peritoneal fluid might have a diagnostic value equivalent to that of pleural effusion for discriminating malignancy.