[Hyperreactio luteinalis in pregnancy]

We report on the extremely rare case of ovarian overstimulation in a single pregnancy without prior hormonal stimulation therapy. During the 26th week of gestation ultrasound examination showed a 103 x 57 x 78 mm polycystic tumour with echogenic structures inside the cysts, located behind the uterus. Further management consisted of laparotomy with partial resection of a cystic part of the left ovary. Frozen section examination confirmed the diagnosis of hyperreactio luteinalis and excluded malignancy. To avoid torsion of the ovaries, cysts from both sides were aspirated. On day 8 and 18 after surgery, sonography revealed no pathological finding. In the 40th week of gestation, a healthy baby was delivered. The possibility of a hyperreactio luteinalis has to be kept in mind, when cystic solid tumours of the ovaries are diagnosed during pregnancy. A conservative management is appropriate, because a normal spontaneous remission occurs after delivery.