Prognostic value of trophoblastic proliferation in complete hydatidiform moles in predicting persistent disease

The clinical outcome of patients with complete hydatidiform moles (CHM) is variable. The correlation between trophoblastic proliferation and development of persistent disease was evaluated. A hundred and fifty-one cases with the initial diagnosis of CHM were re-evaluated histopathologically. The need for chemotherapy and occurrence of metastatic disease was correlated with the histologic grade using a three-level score. Twelve out of 151 cases were re-evaluated as hydropic abortion, partial moles, or were insufficient for morphologic examination, representing a diagnostic agreement of 92%. A total of 63.4% of the CHM presented with low trophoblastic proliferation with focal areas of slight hyperplasia (grade 1), and 23.7% with moderate proliferation with slight anaplasia and medium-sized sheets of free trophoblast in between the villies (grade 2). In all, 12.9% of the cases showed marked hyperplasia with marked anaplasia and involvement of nearly all villies, as well as a large amount of intervillous trophoblastic sheets (grade 3). Twenty-six of the CHM (19%) required chemotherapy. Grade 3, on histology, showed a positive correlation with the necessity of chemotherapy (p=0.04), but not with the occurrence of metastatic disease. Histomorphology might predict the risk of persistent disease, indicating the necessity for closer a follow-up, but further studies are required.