p63

p63, a homolog of the tumor suppressor p53, has been identified in basal cells in the epithelial layers of a variety of tissues, including epidermis, cervix, urothelium, breast and prostate (1). p63 was detected in nuclei of the basal epithelium in normal prostate glands; however, it was not expressed in malignant tumors of the prostate (2). As a result, p63 has been reported as a useful marker for differentiating benign from malignant lesions in the prostate, particularly when used in combination with markers of high molecular weight cytokeratins and the prostate-specific marker AMACR (P504S) (3-4). p63 has also been shown to be a sensitive marker for lung squamous cell carcinomas (SqCC), with reported sensitivities of 80-100% (5-8). Specificity for lung SqCC, vs. lung adenocarcinoma (LADC), has been reported to be approximately 70-90%, as positive staining with p63 has been typically observed in 10-30% of LADC cases (5-8). In breast tissue, p63 has been identified in myoepithelial cells of normal ducts (9). Reports have described the utility of p63 in a panel of IHC markers for the assessment of breast lesions, due to the differential expression of the luminal vs. basal and myoepithelial markers (9-11).

Specifications

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1. Yang A, et al. p63, a p53 homolog at 3q27–29, encodes multiple products with transactivating, death-inducing, and dominant-negative activities. Mol Cell. 1998 Sep;
2(3):305-16.
2. Signoretti S, et al. p63 is a prostate basal cell marker and is required for prostate development. Am J Pathol. 2000 Dec; 157(6):1769-75.
3. Paner GP, Luthringer DJ, Amin MB. Best practice in diagnostic immunohistochemistry: prostate carcinoma and its mimics in needle core biopsies. Arch Pathol Lab Med. 2008 Sep; 132(9):1388-96.
4. Humphrey PA. Diagnosis of adenocarcinoma in prostate needle biopsy tissue. J Clin Pathol. 2007 Jan; 60(1):35-42.
5. Mukhopadhyay S, Katzenstein AL. Subclassification of non-small cell lung carcinomas lacking morphologic differentiation on biopsy specimens: Utility of an immunohistochemical panel containing TTF-1, napsin A, p63, and CK5/6. Am J Surg Pathol. 2011 Jan; 35(1):15-25.
6. Tacha D, et al. A six antibody panel for the classification of lung adenocarcinoma versus squamous cell carcinoma. Appl Immunohistochem Mol Morphol. 2012 May; 20 (3):201-7.
7. Terry J, et al. Optimal immunohistochemical markers for distinguishing lung
adenocarcinomas from squamous cell carcinomas in small tumor samples. Am J Surg
Pathol. 2010 Dec; 34(12):1805-11.
8. Pu RT, Pang Y, Michael CW. Utility of WT-1, p63, MOC31, mesothelin, and
cytokeratin (K903 and CK5/6) immunostains in differentiating adenocarcinoma,
squamous cell carcinoma, and malignant mesothelioma in effusions. Diagn Cytopathol.
2008 Jan; 36(1):20-5.
9. Lerwill MF. Current practical applications of diagnostic immunohistochemistry in
breast pathology. Am J Surg Pathol. 2004 Aug; 28(8):1076-91.
10. Hicks DG. Immunohistochemistry in the diagnostic evaluation of breast lesions.
Appl Immunohistochem Mol Morph. 2011 Dec; 19(6):501-5.
11. Yeh IT, Mies C. Application of immunohistochemistry to breast lesions. Arch Pathol Lab Med. 2008 Mar; 132(3):349-58.
12. Center for Disease Control Manual. Guide: Safety Management, NO. CDC-22, Atlanta, GA. April 30, 1976 “Decontamination of Laboratory Sink Drains to Remove Azide Salts.”
13. Clinical and Laboratory Standards Institute (CLSI). Protection of Laboratory workers from occupationally Acquired Infections; Approved guideline-Third Edition CLSI document M29-A3 Wayne, PA 2005.