To investigate the clinicopathological features, immunohistochemical phenotypes and molecular characteristics of adenosquamous carcinoma of the lung(ASC)in elderly patients.

Clinical data of 72 ASC patients in the Department of Pathology, The Second Affiliated Hospital of Soochow University from January 2009 to December 2020 were retrospectively analyzed, and 48 patients aged ≥60 years were selected.Clinical manifestations, imaging findings, histopathological and immunohistochemical characteristics were collected, and gene mutations were detected by the amplification refractory mutation system(ARMS-PCR).

There were 48 patients including 32 males and 16 females with a mean age of 70 years(range: 60-84 years). The maximum diameters of the tumors ranged from 0.3 to 9.0 cm(mean: 2.8 cm). Microscopically, the tumors contained two components, squamous cell carcinoma and adenocarcinoma, with the squamous cell carcinoma tissue showing intercellular bridges and the adenocarcinoma tissue showing papillary, acinar or tubular structures.Immunohistochemistry assays detected varying expression levels of CK7(30/31), CK5/6(20/28), TTF1(12/31), P40(15/17), and P63(12/13). Molecular testing showed that the EGFR mutation rate was 58.8%(10/17)and the ALK fusion mutation rate was 5.9%(1/17), while ROS1 and MET mutations were not detected.All 48 patients underwent surgical resection.

ASC cases are relatively rare and prone to misdiagnosis.The diagnosis requires the combination of HE morphology, immunohistochemistry and imaging examination, and surgery is the main treatment option.The mutation rate of the EGFR gene is relatively high in ASC patients.

Lung neoplasms; Pathology, clinical; DNA mutational analysis