Hyperreactio luteinalis masquerading as an ovarian neoplasm in a triplet pregnancy.

Hyperreactio luteinalis is a non-neoplastic tumor-like ovarian lesion associated with pregnancy. Most patients are asymptomatic, with the ovarian enlargement being incidentally discovered at the time of cesarean section. It can simulate a neoplasm on clinical, gross and sometimes microscopic examination. We report a case of hyperreactio luteinalis in a patient, who was diagnosed as having polycystic ovary disease before conceiving a triplet pregnancy after three treatment cycles of human menopausal gonadotropin-human chorionic gonadotropin therapy, and discuss its pathogenesis.