Elastin fibers in the sputum of patients with necrotizing pneumonia.

We have observed five patients for whom the presence of fibers of elastin in potassium hydroxide (KOH) preparations of sputum represented the first evidence of necrotizing pulmonary disease. In four cases, the discovery of elastin fibers in sputum provided additional evidence supporting initiation or modification of antibiotic therapy. Necrotizing disease was confirmed in all cases by autopsy or by the development of cavitation on chest x-ray film. Cytochemical staining, electron microscopy, and elastase digestion all suggest that the refractile fibers seen on KOH wet mount of sputum are elastin. The test, first described in 1846, is simple to perform, requires little experience to read, and may be a valuable adjunct to the chest roentgenogram in the diagnosis of pulmonary parenchymal destruction.