[Silicosis characterized by increasing serum CA 19-9 in parallel with progression of lung fibrosis]

In November 1997, a 61-year-old man was admitted to our hospital complaining of dyspnea. He had worked as a miner for 10 years and had received medical treatment based on a diagnosis of idiopathic interstitial pneumonia at our hospital since 1984. In conjunction with the progression of interstitial pneumonia, the patient's serum CA 19-9 had gradually increased since 1992, reaching 9,920 U/ml in 1997. Though cancer of the pancreas or other organs was suspected, an extensive examination revealed no malignancy. In April 1998, the patient died of bacterial pneumonia. Lung autopsy specimens disclosed severe interstitial fibrosis with prominent silicotic nodules. Based on these findings, silicosis was diagnosed. In immunohistochemical staining for CA 19-9, the lumina of severely fibrotic lesions covered with epithelial cells stained positively with anti-CA 19-9 antibody. These findings suggested that serum CA 19-9 may have been produced in the epithelial cells. We speculated that increased serum CA 19-9 levels in patients with interstitial pneumonia may occasionally be more indicative of the magnitude of destruction of lung architecture than the degree of disease activity.