[Two cases of interstitial pneumonitis with marked increase of tumor-associated carbohydrate antigens in serum].

Tumor-associated carbohydrate antigens, CA19-9 and SLEX have been used clinically as markers for malignancy. However, it is also known that these antigens are frequently elevated in the serum of patients with benign lung diseases. We have experienced two cases of interstitial pneumonitis with marked increase of carbohydrate antigens in serum, the level of which changed according to their clinical course. Case 1. A 64-year-old woman was admitted because of a cough and exertional dyspnea. Despite treatment with various antibiotics and prednisolone, she died of respiratory failure approximately two months after admission. Her CA19-9 and SLEX in serum elevated from 500 U/ml to 5506 U/ml and 167 U/ml to 1187 U/ml respectively in accordance with clinical deterioration. Autopsy revealed no malignancy. Case 2. A 57-year-old woman, who had been suffering from interstitial pneumonitis associated with rheumatoid arthritis, was admitted with a cough and fever. She responded to prednisolone therapy, however two years later she readmitted because of exacerbation and died of respiratory failure. The initial CA19-9 level in serum was 876 U/ml and dropped to 42 U/ml with prednisolone therapy. The serum antigen level again increased during the period of exacerbation, and showed 133 U/ml immediately before death. An immunohistochemical study of CA19-9 and SLEX in various tissues obtained by autopsy was performed in case 1. The distribution of these antigens in tissue was similar to that of normal individuals. The exceptions were the expression of these antigens on epithelial cells of microscopic honeycombing and on mucinous exudates in air spaces.