title: Reevaluation and reclassification of resected lung carcinomas originally diagnosed as squamous cell carcinoma using immunohistochemical analysis.
abstract: Currently, non-small cell lung carcinomas are primarily classified by light microscopy. However, recent studies have shown that poorly differentiated tumors are more accurately classified by immunohistochemistry. In this study, we investigated the use of immunohistochemical analysis in reclassifying lung carcinomas that were originally diagnosed as squamous cell carcinoma. Tumor slides and blocks were available for histologic evaluation, and tissue microarrays were constructed from 480 patients with resected lung carcinomas originally diagnosed as squamous cell carcinoma between 1999 and 2009. Immunohistochemical analyses for p40, p63, thyroid transcription factor-1 (TTF-1; clones SPT24 and 8G7G3/1), napsin A, chromogranin A, synaptophysin, and CD56 were performed. Staining intensity (weak, moderate, or strong) and distribution (focal or diffuse) were also recorded. Of all, 449 (93.5%) patients were confirmed as having squamous cell carcinomas; the cases were mostly diffusely positive for p40 and negative for TTF-1 (8G7G3/1). Twenty cases (4.2%) were reclassified as adenocarcinoma, as they were positive for TTF-1 (8G7G3/1 or SPT24) with either no or focal p40 expression, and all of them were poorly differentiated with squamoid morphology. In addition, 1 case was reclassified as adenosquamous carcinoma, 4 cases as large cell carcinoma, 4 cases as large cell neuroendocrine carcinoma, and 2 cases as small cell carcinoma. In poorly differentiated non-small cell lung carcinomas, an accurate distinction between squamous cell carcinoma and adenocarcinoma cannot be reliably determined by morphology alone and requires immunohistochemical analysis, even in resected specimens. Our findings suggest that TTF-1 8G7G3/1 may be better suited as the primary antibody in differentiating adenocarcinoma from squamous cell carcinoma.
authors: *Thoracic Service, Department of Surgery †Department of Pathology ∥Center for Cell Engineering, Memorial Sloan Kettering Cancer Center, New York, NY ‡Department of Diagnostic Pathology, Faculty of Medicine, Kagawa University, Kagawa §Department of Thoracic Surgery, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
authors: Kyuichi
authors: K
authors: Kadota
authors: Jun-ichi
authors: J
authors: Nitadori
authors: Natasha
authors: N
authors: Rekhtman
authors: David R
authors: DR
authors: Jones
authors: Prasad S
authors: PS
authors: Adusumilli
authors: William D
authors: WD
authors: Travis
mesh_terms: D000230:Adenocarcinoma / Q000737:chemistry* / Q000145:classification / Q000473:pathology / Q000601:surgery; D000077192:Adenocarcinoma of Lung; D014408:Biomarkers, Tumor / Q000032:analysis*; D001706:Biopsy; D002289:Carcinoma, Non-Small-Cell Lung / Q000737:chemistry* / Q000145:classification / Q000473:pathology / Q000601:surgery; D002294:Carcinoma, Squamous Cell / Q000737:chemistry* / Q000145:classification / Q000473:pathology / Q000601:surgery; D002454:Cell Differentiation; D003937:Diagnosis, Differential; D003951:Diagnostic Errors; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000737:chemistry* / Q000145:classification / Q000473:pathology / Q000601:surgery; D009519:New York City; D009687:Nuclear Proteins / Q000032:analysis*; D011013:Pneumonectomy; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D000074482:Thyroid Nuclear Factor 1; D046888:Tissue Array Analysis; D014157:Transcription Factors / Q000032:analysis*
chemical_list: D014408:Biomarkers, Tumor; C000614412:NKX2-1 protein, human; D009687:Nuclear Proteins; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors