A complete hydatidiform mole is evacuated. Histological analysis uses p57kip2 immunostaining for definitive diagnosis. What is the staining pattern seen in complete versus partial mole?

• A Complete mole: p57 positive (cytotrophoblast); Partial mole: p57 negative
• B Both complete and partial moles are p57 negative; genotyping required
• C Complete mole: p57 negative in cytotrophoblast and villous stromal cells; Partial mole: p57 positive ✓
• D p57 positivity in trophoblast confirms complete mole regardless of villous morphology

Explanation

p57kip2 is a maternally imprinted (paternally expressed) gene. In complete hydatidiform mole (androgenetic, diploid with entirely paternal genome), the maternal imprint is absent, so p57 is NOT expressed — cytotrophoblast and villous stromal cells are p57 negative. In partial mole (triploid, biparental genome with maternal contribution), maternal imprinting is present and p57 is POSITIVE. This distinction is critical: p57 negativity confirms complete mole. Residual maternal decidua cells serve as an internal positive control in any specimen.

Reference: Williams Obstetrics, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.