ABSTRACT
Adenosquamous carcinoma (ASC) of the lung is a unique type of lung cancer. The pathological definition is a carcinoma showing components of both squamous cell carcinoma (SCC) and adenocarcinoma, with each accounting for ≥10% of the tumor. Definitive diagnosis requires a resection specimen sampled appropriately. Biopsy and cytology can not make the diagnosis of adenosquamous carcinoma. The research by applying microdissection and next-generation sequencing showed that the genotype of adenocarcinoma component and SCC component in ASC are similar, which is very close to the pure adenocarcinoma and significantly different from the pure SCC. So far, the theory of common precursor stem cell differentiating to adenocarcinoma and SCC is the most accepted among the hypotheses about adenocarcinoma origin.