Topic Completed: 1 April 2012

Revised: 18 January 2019

Copyright: (c) 2002-2019,, Inc.

PubMed Search: p63 [title]
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Cite this page: Pernick N p63. website. Accessed March 23rd, 2019.
Definition / general
  • Member of p53 gene family at 3q27-29, but does not appear to be a tumor suppressor gene
  • Myoepithelial marker; others are smooth muscle myosin heavy chains, calponin, p75, P-cadherin, basal cytokeratins (CK 5 / 6), maspin and CD10 (Arch Pathol Lab Med 2011;135:422)
  • Encodes at least 6 different proteins with different biologic functions
  • Appears to regulate growth and development of epithelial organs (J Biomed Biotechnol 2011;2011:864904), as germline mutations cause ectrodactyly (missing or irregular fingers or toes), ectodermal dysplasia and facial clefts syndrome, also called limb mammary syndrome (hypoplasia / aplasia of mammary glands and nipple)
  • May be molecular switch for initiation of "epithelial stratification program"
  • Regulates human keratinocyte proliferation (J Biol Chem 2012;287:5627), olfactory stem cell self renewal and differentiation (Neuron 2011;72:748)
  • Gene and protein expression may not correlate due to presence of isoforms and post translation modification
  • Main isoforms are TAp63 and deltaNp63
  • TAp63 ("full length" p63) activates p53 target genes but deltaNp63 inhibits transcription activation of p53 gene and transactivating isoforms
  • TAp63 is highly expressed in most benign tumors; negative / weak in most carcinomas but deltaNp63 is negative / weak in most benign tumors and highly expressed in adenoid cystic, mucoepidermoid and myoepithelial carcinomas (Hum Pathol 2005;36:821)
  • Typically a nuclear stain
  • Cytoplasmic staining of Z bands of benign and malignant skeletal muscle tumors (Mod Pathol 2011;24:1320)
Uses by pathologists
Microscopic (histologic) images

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Thyroid, contributed by Andrey Bychkov, M.D., Ph.D.

Solid cell nests

p63+ cells found in many follicles

Intense immunostaining
correlates with a loss
of TTF-1 expression

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Adenoid cystic carc, solid

Nasal septum:
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Seromucinous hamartoma p63−, no myoepithelial cells, positive internal control

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Nephrogenic adenoma

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Pseudohyperplastic adenocarcinoma

Images hosted on other servers:

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Normal and carcinoma anal glands

Bladder / other GU:
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Normal and carcinoma urothelium

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Invasive UC

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Various bone tumors

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Tubular adenoma

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Nipple adenoma, p63 shows intact myoepithelial layer

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p63, Fig.C

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Medullary carcinoma

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Myoepithelial carcinoma

Lymph nodes:
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Benign epithelial inclusions

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Anaplastic large cell lymphoma

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Hodgkin lymphoma

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Nasolabial cyst

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Respiratory epithelial adenomatoid hamartoma

Nasal septum:
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Intraductal carcinoma

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carcinoma papilliferum

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Sweat gland carcinoma

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Positive staining - normal
  • Breast: myoepithelium (Am J Surg Pathol 2001;25:1054), Toker cells
  • Gynecologic tract: basal and parabasal cells of mature cervical, vaginal and vulval squamous epithelium; cervical reserve cells at transformation zone, immature metaplastic and atrophic cervical squamous epithelium (Adv Anat Pathol 20 09;16:316)
  • Lung: bronchial reserve cells; metaplastic squamous bronchial epithelium (lower strata)
  • Also prostate (basal cells), skin (basal cells), thymus (epithelial cells), urothelium
Positive staining - disease
Negative staining
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