Mucinous bronchioloalveolar carcinomas display a specific pattern of mucingene expression among primary lung adenocarcinomas

Lung adenocarcinomas are heterogeneous clinically and histologically. Expre ssion of the mucin genes was analyzed as a molecular marker of glandular cy todifferentiation in primary lung adenocarcinomas. Expression was correlate d with histopathologic subtypes of World Health Organization classification with the aim of investigating the histogenesis of primary lung adenocarcin omas, Thirty-four primary lung adenocarcinomas were examined by in situ hyb ridization for mucin gene expression (MUC1-4, MUC5AC,MUC5B, MUC6-7) and by immunohistochemistry for MUC5AC and MUC5B apomucin expression. Mucinous bro nchioloalveolar carcinoma (BAG) had a homogeneous pattern of mucin gene exp ression different from those of other types of lung adenocarcinoma, involvi ng secreted mucins (MUC5AC, MUC5B, and MUC6) and membrane-bound mucins (MUC 1, MUC3, and MUC4). Non-BAG adenocarcinoma and mucinous BAC aberrantly expr essed mucin genes MUC3, and MUC3 and MUC6, respectively, which are undetect able in normal fetal and adult lung. Our results show the particular phenot ype of mucin gene expression in mucinous type of BACs and the heterogeneous expression of respiratory and nonrespiratory mucins in the other types. Th is finding supports the theory of a common progenitor cell with the potenti al of multicellular differentiation. From a practical point of view, the ab errant expression of MUC3 and MUC6 could serve as a diagnostic marker in th e management of the mucinous type of bronchioloalveolar carcinomas. HUM PAT HOL 32:274-281. Copyright (C) 2001 by W.B. Saunders Company.