Bronchial epithelial changes associated with small cell carcinoma of the lung

From 1976 to 1991, 151 cases of small cell carcinoma of the lung were diagnosed by fiberoptic bronchoscopic biopsy at our institution. One hundred twenty-eight of 151 cases provided suitable material for the examination of the morphologic changes in the bronchial surface epithelium. Thirty-seven percent of the cases showed normal bronchial epithelium, 47% showed benign squamous metaplasia, 9% showed atypical squamous metaplasia, and 5% showed squamous cell carcinoma in situ. Immunohistochemical examination for bombesin and epidermal growth factor was performed on selected biopsy specimens. The biopsy specimens chosen for immunohistochemistry included 20 specimens that showed normal bronchial epithelium, 20 specimens with benign squamous metaplasia, 12 specimens with atypical squamous metaplasia, and seven specimens with squamous cell carcinoma in situ. All the specimens showed positive staining with anti-bombesin. With anti-epidermal growth factor 10% of biopsy specimens with normal epithelium showed positive staining. The positive reaction increased from 25% for biopsy specimens with benign squamous metaplasia to 58% for biopsy specimens with atypical squamous metaplasia and to 71% for biopsy specimens with carcinoma in situ. These findings suggest a connection between epidermal growth factor production by small cell carcinoma of the lung cells and changes in the bronchial surface epithelium.