[Clinicopathologic Features and Genetic Profile of the Redefined Large Cell Lung Carcinoma]

To investigate the clinicopathologic features and genetic profile of large cell lung carcinoma (LCC) redefined by new classification. Basing on 2015 WHO classification criteria in redefining large cell lung carcinoma, the expression of specific markers (TTF1, Napsin A, p40, CK5/6, CK, vimentin and ZEB1) was detected by immunohistochemistry and D-PAS staining in 303 surgically-removed lung specimens previously diagnosed as large cell lung carcinoma. The clinicopathologic and genetic characteristics (including EGFR, KRAS, BRAF, ALK and ROS1 gene mutation) were analyzed. Based on the new definition of LCC, 116 cases (116/303, 38.3%) of LCC formerly diagnosed were reclassified as solid adenocarcinoma, 49 cases (49/303, 16.2%) as squamous cell carcinoma, 6 cases (6/303, 2.0%) as adenosquamous carcinoma, 22 cases (22/303, 7.3%) as spindle cell carcinoma and only 110 cases (110/303, 36.3%) as large cell carcinoma. Redefined LCCs were characterized as middle-age (range 40-80), male (102/110, 92.7%) and smoking patients (64/110, 58.2%) with intermediate-advanced stage. Among 110 cases, 9 cases with EGFR mutation and 10 cases with KRAS mutation and 1 case with ALK fusion were found. No BRAF and ROS1 alterations were identified. According to the new classification, LCCs formerly diagnosed are mostly reclassified as adenocarcinoma and non-keratinizing squamous cell carcinoma. The newly defined LCC may significantly benefit from clinical therapy.