title: Value of p63 and cytokeratin 5/6 as immunohistochemical markers for the differential diagnosis of poorly differentiated and undifferentiated carcinomas.
abstract: To facilitate the differential diagnosis of poorly differentiated metastatic carcinomas of unknown primary site, we evaluated p63 and cytokeratin (CK) 5/6 as immunohistochemical markers for squamous cell carcinomas. The study cases were as follows: squamous cell carcinoma of the lungs, head/neck, esophagus, cervix uteri, or anal canal, 73; non-squamous cell carcinomas of various primary sites, 141; and urothelial carcinoma, 20. We also tested 14 malignant mesotheliomas. Immunoreactivity for p63 was as follows: squamous cell carcinomas, 59 (81%); urothelial carcinoma, 14 (70%), most often with diffuse staining patterns; non-squamous cell carcinomas, 20 (14.2%), resulting in a specificity of 0.86 of p63 for squamous cell carcinomas. Coexpression of p63 and CK5/6 had a sensitivity of 0.77 and a specificity of 0.96 for squamous cell carcinomas. Increasing the minimal criterion of positive immunostaining for both markers to more than 50% of immunoreactive tumor cells resulted in a specificity of 0.99, although the sensitivity diminished to 0.66. All malignant mesotheliomas were negative for p63. Our data suggest that positive immunostaining for both p63 and CK5/6 in poorly differentiated metastatic carcinomas is highly predictive of a primary tumor of squamous epithelial origin.
authors.affiliation: Institute of Pathology, Charité University Hospital, Berlin, Germany.
authors.forename: O
authors.initials: O
authors.lastname: Kaufmann
authors.forename: E
authors.initials: E
authors.lastname: Fietze
authors.forename: J
authors.initials: J
authors.lastname: Mengs
authors.forename: M
authors.initials: M
authors.lastname: Dietel
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D002294:Carcinoma, Squamous Cell / Q000737:chemistry* / Q000556:secondary; D004268:DNA-Binding Proteins; D003937:Diagnosis, Differential; D005260:Female; D016147:Genes, Tumor Suppressor; D006801:Humans; D007124:Immunoenzyme Techniques; D053555:Keratin-5; D007633:Keratins / Q000032:analysis*; D008297:Male; D008565:Membrane Proteins; D009382:Neoplasms, Unknown Primary / Q000737:chemistry* / Q000473:pathology; D010750:Phosphoproteins / Q000032:analysis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015534:Trans-Activators / Q000032:analysis*; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins
chemical_list: D014408:Biomarkers, Tumor; C081876:CKAP4 protein, human; D004268:DNA-Binding Proteins; C503940:KRT5 protein, human; D053555:Keratin-5; D008565:Membrane Proteins; D010750:Phosphoproteins; C115051:TP63 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D007633:Keratins