Role of minimal panel immunostaining in accurate diagnosis of lung cancer using small biopsies

Abstract

Introduction: In small biopsies standard morphology cannot specifically subtype the tumor. Histologic subtyping of lung cancer is mandatory for treatment. Immunohistochemical staining is a valuable tool for diagnosis of lung cancer. Aim: The aim of this study was to evaluate the diagnostic accuracy of minimal panel of Napsin A, CK 5/6 and CD 56 versus H&E of lung cancer in small biopsies. Methods: 84 small sized tissue samples were obtained. Seventy samples were obtained via fiberoptic bronchoscope (FOB) and 14 samples were obtained with transothoracic CT guided trucut needle. All samples were stained with H&E for morphologic diagnosis, then the same samples were stained with immunohistochemical (IHC) staining including 3 antibodies (Napsin A, CK 5/6 and CD 56), then we compared the diagnostic yield of both methods. Results: After H&E staining, according to WHO 2004 classification: 40 cases were adenocarcinoma (AC), 10 were squamous cell carcinoma (SCC), 22 were large cell carcinoma (LCC) and 12 were neuroendocrine tumors (NET). After IHC; 54 (64.3%) were AC, 11 (13.1%) were SCC, 11 (13.1%) were NET and 8 (9.5%) were non small cell lung cancer not otherwise specified NSCLC NOS (Counterpart of large cell carcinoma in 2004 WHO classification). Napsin A was expressed in 98% (53/54) and CK 5/6 in 90.9% (10/11) of SCC. CD 56 in 100% (11/11) of neuroendocrine tumors. Conclusion: IHC with Napsin A, CK 5/6 and CD 56 has a more diagnostic value in precise typing of different cell types of lung cancer than H&E in small biopsies.

Keywords

• Lung cancer
• Immunohistochemistry
• Napsin A
• CK 5/6
• CD 56