Non-invasive bronchial epithelial papillary tumors.

Nineteen papillary, non-invasive tumors arising from the bronchial epithelium but excluding carcinoid tumors are reviewed. Eight were solitary papillomas of which three were covered with a mixture of epithelial types. Seven were benign but one had a focus of carcinoma in situ. A similar change was seen in bronchial epithelium adjacent to a papilloma. Two cases of recurrent papillomas were seen and in one, carcinomatous changes eventually occurred. Two combined benign brochial cystadenomas with papillomas are described. One transitional celled papillary carcinoma in situ and five other papillary carcinomas in situ are described. One bronchial papilloma covered with dysplastic epithelium was considered an intermediate stage in the development of carcinoma in situ. Two papillary tumors may have arisen from peripheral bronchi or brochioles. Their lining cells resembled Clara cells, they grew by local expansion, and there was an absence of malignant features. The differential characteristics of two secondary carcinomatous polypoidal tumors are described.