Differentiating bronchioloalveolar carcinoma from adenocarcinoma

The recognition of bronchioloalveolar carcinoma (BAC) as distinct from adenocarcinoma of the lung, is controversial. Using strict pathologic criteria, 43 consecutive patients with BAC were matched by year of diagnosis and compared with a similar number of patients with adenocarcinoma, and for contrast, with those with squamous and oat cell carcinoma of the lung. We demonstrated that BAC is not sex related, and is not as smoking related as the other neoplasms. Unlike epidermoid carcinoma, BAC does not show a predilection for those occupations requiring manual labor. Also, BAC is frequently distinguishable radiologically from the other three by being smaller and peripheral. A pleural tag and an air bronchogram in a mass are rather specific, and BAC is less likely to have large airway involvement and adenopathy. The percentage of patients who were free of tumor after 2 yr was greater in the BAC group than in the others, but the overall survival rate between the BAC group and the adenocarcinoma group was not. Based on inter-observer variability, there is some overlap pathologically between these 2 groups. However, when the overlap between the adenocarcinoma and the BAC groups is compared with that between the adenocarcinoma and the squamous cell carcinoma groups, the difference is not significant. We conclude that BAC should be considered a distinct clinical entity.