Cytologic study of tissue repair in human bronchial epithelium.

The cytologic findings of atypical cells considered to be tissue repair cells after mechanical injury to the bronchial epithelium are reported. These cells were studied in sequential bronchial brushing smears from patients who underwent repeated bronchoscopies for the diagnosis of lung cancer. The cellular findings varied according to the length of time since the previous bronchial brushing. Many cell clusters of highly atypical cells in two-dimensional sheets with large nuclei and prominent nucleoli were observed in specimens taken two or three days after a previous brushing; mitotic figures were observed on day two. In specimens taken on days four and five, the number of atypical cells was decreased and the degree of atypia was slight.