Table 1. 2011 International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification of lung adenocarcinoma in research specimens.

Pre-invasive lesions

Atypical adenomatous hyperplasia

Adenocarcinoma in situ (≤3 cm formerly solitary BAC)

Non-mucinous

Mucinous

Mixed mucinous/nonmucinous

Minimally invasive adenocarcinoma (≤3 cm lepidic predominant tumour with ≤5 mm invasion)

Nonmucinous

Mucinous

Mixed mucinous/nonmucinous

Invasive adenocarcinoma

Lepidic predominant (formerly nonmucinous BAC pattern with >5 mm invasion)

Acinar predominant

Papillary predominant

Micropapillary predominant

Solid predominant with mucin production

Variants of invasive adenocarcinoma

Invasive mucinous adenocarcinoma (including formerly mucinous BAC)

Colloid

Fetal (low and high grade)

Enteric

BAC: bronchoalveolar carcinoma. Reproduced from [11] with permission from the publisher.