Products of conception evacuated at 11 weeks show swollen grape-like villi with diffuse trophoblastic proliferation and no fetal parts. Cytogenetics shows a 46,XX karyotype entirely of paternal origin. Immunohistochemistry for p57 shows complete absence of staining in cytotrophoblast and villous stromal cells. What is the diagnosis?

• A Partial hydatidiform mole
• B Placental site trophoblastic tumor
• C Complete hydatidiform mole ✓
• D Hydropic abortus

Explanation

Complete mole is androgenetic, diploid and entirely paternal in origin, usually 46,XX from duplication of a single sperm genome. Because p57 (CDKN1B) is expressed only from the maternal allele, complete moles show absent p57 staining in cytotrophoblast and villous stroma, while extravillous trophoblast stains internally. Partial moles retain maternal DNA and stain positively, as do hydropic abortuses.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.