Exceedingly rare lactating adenoma of three-year duration: a case report

Abstract

Lactating adenoma (LA) is a benign breast tumor of pregnancy that most often regresses spontaneously after cessation of breastfeeding. LA are described as tubular adenomas with secretory changes that occur during pregnancy and lactation. We present a rare case report of a persisting lactating adenoma of three-year duration. This is the longest lasting lactating adenoma reported in the literature. LA present as firm, mobile and painless masses. On ultrasonography LA are generally described as having an ovoid shape with smooth borders and being a well-circumscribed hypoechoic solid mass. Therefore, lactating adenomas are difficult to distinguish from other benign breast lesions and falls within a differential diagnosis consisting of fibroadenoma, galactocele or lobular hyperplasia. Malignancy, although rare, needs to be excluded. LA can only be definitively diagnosed with a thorough history, physical examination, and a histopathological specimen. Our patient presented 1 month postpartum with a left breast lump. Careful examination revealed a 2 cm firm and rounded nodule in the superior central aspect of her left breast. She underwent a core needle biopsy confirming lactating adenoma. Despite cessation of lactation, the palpable left breast mass persisted. Patient continued to undergo biannual ultrasound examinations that revealed a persistent hypoechoic mass containing the biopsy clip despite cessation of breastfeeding. Therefore, surgical excision was warranted. Patient underwent open biopsy with ultrasound guidance of the mass. Pathology revealed presence of tubular adenoma without evidence of malignancy in our nonlactating patient. This case highlights that surgical excision is the only method to exclude co-existing malignancy reliably and accurately in cases of lactating adenomas that do not regress.