Diagnostic aspects of hydatidiform mole with persistence of polymorphic trophoblastic hyperplasia

The persistence of polymorphic trophoblastic hyperplasia in a hydatidiform mole is an extremely rare condition. Its early recognition is essential since such cases can transform into invasive types of tumors.

The biopsies were routinely processed in paraffin, embedded and stained with HE. Immunohistochemical staining reactions were performed with the following monoclonal antibodies for hydatidiform mole: beta-hCG, HPL, MIB1, CK18, HER-2/neu, p53 and carbohydrate antibodies, Thomsen-Friedenreich antigen, Glycodelin A, Mucl and Mucl-cor.

Large villi and hydatidiform villi with wide-ranged syncyctio- and cytotrophoblasts were seen. Intervillous proliferating trophoblasts showed cell- and nuclear polymorphy with a wall invasion of the myometrium. The immunohistochemistry exhibited strong positivity for the membrane-associated HER-2/neu and for the beta-hCG in syncytiotrophoblast and in multinuclear giant cells of intervillus trophoblasts. A weakly positive reaction with hPL was seen in most cells of the trophoblasts. The rest of the immunohistochemistry served as a diagnostic support.

A complete hydatidiform mole with hyperplasia and proliferation of polymorphic trophoblasts presents a high risk of developing a persistent (eventually metastatic) trophoblastic disorder and, in up to 15% of the cases, an invasive mole. In 2.5% of the cases it can transform into a choriocarcinoma.