Table 1. Pathology of lung adenocarcinomas according to previous 2004 WHO and current IASLC/ATS/ERS classifications.
| 2004 WHO classification |
| Mixed subtype |
| Acinar |
| Papillary |
| BAC |
| Non mucinous |
| Mucinous |
| Mixed |
| Solid adenocarcinoma |
| Colloid |
| Fetal |
| Mucinous cystadenocarcinoma |
| Signet-ring |
| Clear-cell |
| Major changes in the new IASLC/ATS/ERS classification |
| Discontinuation of the term BAC |
| Discontinuation of the mixed subtype |
| Comprehensive pathologic subtyping in 5% increments and classification of adenocarcinomas according to the predominant subtype |
| Introduction of AIS and MIA as new entities |
| Introduction of micropapillary adenocarcinoma as a predominant subtype |
| Introduction of lepidic predominant adenocarcinoma and lepidic growth as new terminologies |
| Exclusion of signet-ring and clear cell adenocarcinomas |
| IASLC/ATS/ERS classification |
| Pre-invasive lesions |
| Atypical adenomatous hyperplasia |
| AIS |
| Non-mucinous |
| Mucinous |
| Mixed |
| MIA |
| Non-mucinous |
| Mucinous |
| Mixed |
| Invasive adenocarcinomas |
| Lepidic predominant |
| Acinar predominant |
| Papillary predominant |
| Micropapillary predominant |
| Solid predominant with mucin production |
| Variants of invasive adenocarcinomas |
| IMA |
| Colloid |
| Fetal |
| Enteric |
WHO, World Health Organization; IASLC, International Association for the Study of Lung Cancer; ATS, American Thoracic Society; ERS, European Respiratory Society; BAC, bronchioloalveolar carcinoma; AIS, adenocarcinoma in situ; MIA, minimally invasive adenocarcinoma; IMA, invasive mucinous adenocarcinoma.