[The relationship between adenomatous hyperplasia of alveolar epithelium and bronchioalveolar carcinoma]

Surgical specimens of 7 cases of bronchioalveolar carcinoma complicated with pulmonary fibrosis and 4 cases of simple pulmonary fibrosis were examined histopathologically and immunohistochemically. The morphology and histogenesis of adenomatous hyperplasia (AH) of alveolar epithelium and its relation to bronchioalveolar carcinoma were investigated. The AH was classified as types I and II according to their microscopic morphologic characteristics. In this group, 6 cases of type I-AH and 5 cases of type II-AH were observed. The results of anti-SA, anti-SSEA-1 and anti-CEA monoclonal antibody examinations indicate that AH is a nonspecific hyperplastic lesion of alveolar epithelium occurred during chronic pulmonary inflammatory diseases. Both type I and II AH originated from type B alveolar epithelial cells. The latter developed on the basis of the former, but with a more immature tendency and hyperplastic potential, being a pre-malignant alteration. It could be considered that certain cases of bronchioalveolar carcinoma are originated from type B alveolar epithelial cells, some of which underwent malignant change from type II alveolar hyperplasia.