Invasive Hydatidiform Mole:
A tumor or tumor-like process invading the myometrium, and characterized by trophoblastic hyperplasia and persistence of placental villous structures. It commonly results from complete hydatidiform mole but may do so from partial hydatidiform mole. Invasive mole may metastasize but it does not exhibit the progression of a true cancer, and it may regress spontaneously. (Holland et al., Cancer Medicine, 3d ed, p1691)
