RESUMEN
BACKGROUND: Adenosquamous carcinoma of the lung involves both adenocarcinoma and squamous cell carcinoma, each comprising at least 10% of the tumor. Atypical adenomatous hyperplasia (ADH), bronchiolar columnar cell dysplasia (BCCD), basal cell dysplasia (BCD), columnar cell dysplasia (CCD), bronchial epithelial dysplasia with transitional differentiation (BEDT) and squamous dysplasia (SD) are preinvasive lesions. The aim of this study is to define the preinvasive lesions and evaluate the role of MUC1, bcl-2, and the preinvasive and invasive components of adenosquamous carcinoma. METHODS: A group of 31 patients with adenosquamous carcinoma of the lung were selected. The ratio of squamous to glandular differentiation, the associated preinvasive lesions, the features of peritumoral tissue, the stroma of the tumor, necrosis, perineural and vascular invasion were analyzed. For the immunohistochemical study, blocks containing squamous cell carcinoma, adenocarcinoma and preinvasive lesions were selected. MUC1 and bcl-2 analyses were performed by the immunoperoxidase method using the avidin-biotin complex. RESULTS: Associated preinvasive lesions amd SD, BCCD, BEDT, AAH and CCD were observed in 24, 6, 3, 1 and 6 cases, respectively. Expression for MUC1 was positive in the squamous component of 30 cases, the adenocarcinoma component of 27 cases and in 34 preinvasive lesions. A strong correlation was found between MUC-1 expression in the squamous component and tumor localization (p = 0,01). The positive expression of Bcl-2 in the adenocarcinomatous component was correlated with the presence of preinvasive lesions (p = 0,01). CONCLUSIONS: Squamous dysplasia was the most frequent preinvasive lesion of adenosquamous carcinomas. MUC1 and bcl-2 expression levels were strongly associated with preinvasive lesions in adenosquamous carcinomas.