Pleomorphic carcinoma of the lung: A clinicopathological and immunohistochemical study of 33 cases

Objective Pleomorphic carcinoma(PC) is a rare subtype of non-small cell lung cancer that presents a complex morphology and cellular component,challenging pathologists in its diagnosis and differential diagnosis.This study was to explore the clinical and histopathologic features,immunophenotypes and differential diagnosis of lung PC.Methods The clinicopathologic data of 33 cases of lung PC were retrospectively analyzed.A panel of antibodies including CKpan,CK7,CK5/6,34βE12,CK8/18,P63,TTF-1,napsin A,vimentin,desmin,and SMA were used for EnVision immunohistochemical staining.All the cases were followed up.ResultsCough and hemoptysis,as the most common symptoms,occurred in 29 cases,and 21 of the patients were current-or ex-smokers(mean 956 cigarettes per year),including 19 heavy smokers.Most of the tumors were located in the right and left superior,sized from 1.2 cm to 15.0 cm(mean 5.8 cm) in diameter.Microscopically,neoplastic epithelial cells and pleomorphic components,i.e.neoplasitc spindle cells and/or giant cells,were found in PC in 24 cases,and pleomorphic components only in the other 9.An adenocarcinoma component was observed in 19 cases,a squamous cell carcinoma component in 3,and a mixed adenocarcinoma and large cell carcinoma component in 2.Immunohistochecally,all neoplastic epithelial components showed diffuse and strongly positive staining for CKpan,and negative for vimentin,while the pleomorphic components in all the cases showed diffuse and strongly positive staining for vimentin,23 for CKpan,and 20 for CK8/18.CK7,TTF-1,P63,34βE12,naspin A and CK5/6 were also expressed in some of the cases.Regional lymph node metastasis were found in 8 cases,with malignant epithelial cells as the predominant metastatic components.Follow-up data were available in 25 cases,based on which the overall survival time was 1 to 74 months(median 6 months),and the rates of 1-and 5-year survival were 44.4% and 10%,respectively.Conclusion Pleomorphic carcinoma of the lung usually occurs in older males,often seen in the upper lobes,and maybe associated with smoking.Most cases can be diagnosed by light microscopy alone,and immunohistochemical staining can aid to its diagnosis and differential diagnosis.