WHO Classification of Gestational Trophoblastic Disease, Pathology of the Placenta

Synonyms

Complete hydatidiform mole; Partial hydatidiform mole

Definition

The 5th edition of the World Health Organization (WHO) classification of gestational trophoblastic disease (GTD) covers a spectrum of nonneoplastic lesions and neoplasms of trophoblastic derivation (WHO, 2020). The classification scheme is organized by the putative type of trophoblastic cells giving rise to each entity. Trophoblasts on chorionic villi are classified as synctiotrophoblasts, cytotrophoblasts, or, in anchoring villi trophoblastic columns, as villous intermediate trophoblasts. Chorionic villous trophoblasts are the origin of complete hydatidiform mole, partial hydatidiform mole, and nonmolar lesions with abnormal villous morphology which are sometimes associated with nonmolar fetal aneuploidy. Intermediate trophoblasts are subdivided into three types: (1.) villous intermediate trophoblasts give rise to gestational choriocarcinoma; (2.) implantation site intermediate trophoblasts give rise to...