Change in cytokeratin 19 fragment level according to the severity of pulmonary alveolar proteinosis.

A 48-year-old man was diagnosed with primary alveolar proteinosis (PAP). Whole lung lavage was performed for treatment, and the opacity on his chest X-ray completely disappeared. The value of cytokeratin 19 fragment (CYFRA) in the serum was high at the beginning, decreased after lung lavage, and became elevated again when the disease recurred 7 months later. As PAP is thought to be a problem of surfactant secreted from type II pneumocytes, and a cytokeratin is present in the alveolar epithelial tissue, the value of serum CYFRA might be related to the severity of PAP.