Elevated CYFRA 21-1 level in ascites associated with pulmonary adenocarcinoma

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.