p63

p63 is a nuclear transcription factor of the p53 gene family and a master regulator of epithelial and myoepithelial cell development. In IHC, it shows strong nuclear staining and is widely used as a myoepithelial/basal cell marker in breast and prostate pathology, helping distinguish in situ from invasive lesions through preservation or loss of the basal/myoepithelial layer. p63 is also expressed in squamous and urothelial differentiation, making it a useful marker for squamous cell carcinoma, though less specific than p40(1).

Recommended Controls

Criteria for acceptable staining is a nuclear staining pattern. The recommended positive controls to use include tonsil, SCC of the skin and placenta. In placenta, weak to moderate, distinct nuclear staining reaction of dispersed cytotrophoblastic cells should be seen. While the tonsil will show both positive staining in the squamous epithelial cells and no staining in the majority of lymphocytes. Testes will be a good negative control.

Expected staining pattern

SCC skin

Prostate

Normal testes

Placenta

Skin

Disclaimer

These methods are intended as a guide only. Laboratories that wish to implement these methods should perform internal validation/verification prior to use. The RCPAQAP does not make any claim or warranty for the accuracy or performance of these methods.