title: Combined double CK5/P63 stain: useful adjunct test for diagnosing pulmonary squamous cell carcinoma.
abstract: Increasing demand for accurate differentiation of pulmonary squamous cell carcinoma (SQCC) from other subtypes can be challenging for pathologists. This is more so in fine-needle aspirations (FNA) since the sample is small and SQCC may show degenerative changes and necrosis that distort the cellular features. Immunohistochemistry (IHC) is a valuable adjunct, and CK5/6 and P63 immunoreactivity is found to be basically restricted to SQCC. In our study, we evaluated the efficiency of CK5/P63 double staining in the diagnosis of pulmonary SQCC in cell blocks (CB) of lung FNA. We used a cohort including 24 CB of lung SQCC and 34 CB of lung adenocarcinomas (ADC). IHC was performed for CK5/P63 double stain. Seventeen of 24 (70%) lung SQCC were positive for the double stain CK5/P63. Two (8%) were positive for CK5 alone and two (8%) were positive for P63 alone. Thus, a total 19 of 24(79%) SQCC of the lung were positive for CK5 and P63 each. In ADC, no immunoreactivity was detected for CK5 alone or combined CK5/P63. Three of 34(8%) ADC were positive for P63. This first study of double staining of CK5/P63 in FNA CB shows a sensitivity of 70% and specificity of 100% for SQCC of the lung. When each marker staining alone is included, the sensitivity for CK5 and P63 increases to 79% each. This double stain can help in the diagnosis of pulmonary SQCC with an accuracy of 88% and a positive predictive value of 100%.
authors.affiliation: Department of Pathology, Emory University Hospital, Atlanta, Georgia 30322, USA.
authors.forename: Nazneen
authors.initials: N
authors.lastname: Fatima
authors.forename: Cynthia
authors.initials: C
authors.lastname: Cohen
authors.forename: Diane
authors.initials: D
authors.lastname: Lawson
authors.forename: Momin T
authors.initials: MT
authors.lastname: Siddiqui
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis*; D000077192:Adenocarcinoma of Lung; D000951:Antigens, Neoplasm / Q000032:analysis*; D014408:Biomarkers, Tumor / Q000032:analysis*; D044963:Biopsy, Fine-Needle; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis*; D015331:Cohort Studies; D006416:Hematoxylin; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods*; D053555:Keratin-5 / Q000032:analysis*; D008168:Lung / Q000473:pathology; D008175:Lung Neoplasms / Q000175:diagnosis*; D008565:Membrane Proteins / Q000032:analysis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013194:Staining and Labeling / Q000379:methods
chemical_list: D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; C081876:CKAP4 protein, human; D053555:Keratin-5; D008565:Membrane Proteins; D006416:Hematoxylin