Partial Hydatidiform Mole

High power view of a partial mole showing fibrosis of the villous stroma. Most partial moles are triploid (69,XXX; 69,XXY; 69,XYY). The extra chromosomal haploid set comes from the father. A few cases show trisomy 16. Modest elevation of serum hCG levels may be seen. Partial mole carries a lower risk for persistent gestational trophoblastic neoplasia (1% to 5% of cases) than complete mole; however, careful follow-up with serial hCG monitoring is recommended.