Case report of a large lactating adenoma with rapid antepartum enlargement

Lactating adenomas are rare benign breast tumors, most commonly found during pregnancy and lactation. They are usually slow growing and smaller than 3cm in maximal diameter. Rare cases of giant lactating adenomas and rapid postpartum enlargement have been reported, but none have shown a giant lactating adenoma with rapid antepartum enlargement or antepartum surgical management.

A 27 year-old pregnant woman presented at 28 weeks gestation with a 5cm left breast mass that doubled to 10cm within six weeks and was increasingly tender. Histopathologic examination of a core biopsy was consistent with a lactating adenoma. The mass was excised at 31 weeks gestation with no complications.

Lactating adenomas are common during pregnancy and need to be distinguished from breast cancer, a commonly diagnosed malignancy in pregnancy. They can be distinguished from carcinoma and other benign tumors like fibroadenoma under histopathologic examination. Rare cases of giant lactating adenomas with rapid postpartum enlargement that were managed by postpartum excision have been reported. However, a giant lactating adenoma with rapid antepartum enlargement, managed by excision in the third trimester of pregnancy, has not been reported.

Excision of a large, rapidly enlarging lactating adenoma in the third trimester of pregnancy is a safe and feasible management option.