Idiopathic Interstitial Pneumonia with Increased Serum Levels of Cancer-Associated Antigens, CA19-9 and SLX

We report a case of idiopathic interstitial pneumonia (IIP) with elevated serum levels of carbohydrate antigen 19-9 (CA19-9) and sialyl Lewisx-i (SLX). A 67-year-old Japanese woman was admitted to our hospital with a fever, dry cough and dyspnea on exertion. She had previously been admitted and had then been diagnosed as IIP. The serum level of SLX, measured by radioimmunoassay (RIA), was markedly elevated (120 U/mL; cut-off, < 38 U/mL). The serum level of CA19-9, measured by RIA, was at a slightly high level (46 U/mL; cut-off, < 40 U/mL). The values of CA19-9 and SLX were changed during her clinical course. These cancer-associated antigens were immunohistochemically expressed on the hyperplastic bronchiolar epithelium, on the surface epithelium cells of microscopic honeycombing and on exudates in air space. Repeated damage to the lungs may have forced these antigens of the markers into the blood circulation, which may have resulted in the elevated serum levels of CA19-9 and SLX observed in this patient.