Because of cross reactivity patterns with IHC stains for myoepithelial cells, how many markers are required?

• A. 4
• B. 2
• C. 1
• D. 3

Answer: (B)

Immunohistochemical identification of myoepithelial cells relies on using more than one marker because no single stain perfectly distinguishes them and cross-reactivity can mislead interpretation. A two-marker panel provides confirmatory evidence by combining complementary staining patterns: a nuclear marker (such as p63) and a cytoplasmic/contractile marker (such as calponin or smooth muscle actin). This pairing reduces the chance that non-mmyoepithelial cells are mistaken for myoepithelial cells and increases diagnostic accuracy. In practice, two markers are typically sufficient to confirm myoepithelial differentiation, with a third marker only if ambiguity remains.