Differentiating cytological features of bronchioloalveolar carcinoma from adenocarcinoma of the lung in fine-needle aspirations: a statistical analysis of 27 cases.

Abstract

Bronchioloalveolar carcinoma (BAC) is an uncommon type of lung carcinoma that is important to distinguish from adenocarcinoma (adenoCA) because of its different biological behavior. Although the features of BAC have often been described in cytological material other than fine-needle aspirations (FNA), they have rarely been detailed in FNA specimens. We undertook to delineate the differentiating cytological features of 13 cases of BAC (7 of the nonsecretory type and 6 of the secretory type) and of 14 cases of bronchogenic adenoCA in FNA material, looking at 17 cytological criteria and using statistical analysis. When statistically analyzed with chi-square and Pearson's correlation, only 3 of the 17 features were found to be good discriminants for distinguishing nonsecretory BAC (NS-BAC) from adenoCA: prominence of monolayered tumor sheets, fine chromatin pattern, and mild cellular pleomorphism correlated significantly with NS-BAC. On the other hand, only the prominence of nuclear grooves and the abundance of extracellular mucin correlated significantly with secretory BAC (S-BAC) when compared to adenoCA. When using a logistic regression analysis, NS-BAC and S-BAC were best discriminated from adenoCA by the prominence of monolayered tumor sheets and by the abundance of extracellular mucin, respectively. We conclude that, in most instances, it is possible to make an accurate diagnosis of BAC and to distinguish it from adenoCA of the lung in FNA material.