Abstract
Brenner tumor in pregnancy is rare, with only two reported cases in association with intrauterine pregnancy. A 30-year-old woman, G1P0, was found to have an adnexal mass at 15 weeks of gestation. The mass was resected at Cesarean section and found to be a Brenner tumor with areas of stromal luteinization. Brenner tumor should be considered in the differential diagnosis of adnexal masses presenting during pregnancy. The stromal luteinization was probably related to the hormonal environment of the pregnancy.