Surgical excision of a lactating adenoma with rapid enlargement: A case report

Abstract

Introduction and importance: A lactating adenoma is a benign breast tumor occurring in young women during pregnancy or lactation. Its growth is usually slow but, occasionally, can become rapid, resulting in a giant mass. This case report outlines an example of the rapid growth of a lactating adenoma, which was surgically excised. In this case, malignancy could not be ruled out, and biopsy and surgical excision were considered.

Case presentation: We present the case of a 28-year-old woman referred to us owing to the presence of a left breast mass with progressive enlargement. She initially presented with a left breast mass of approximately 20-mm in size, which increased to an approximate size of 70 mm during pregnancy. The patient's mammogram showed an equal-density lobular mass in the left breast. Ultrasonography and magnetic resonance imaging revealed a circumscribed lobular mass with cystic regions in the upper lateral quadrant. The patient was diagnosed with adenosis using core needle biopsy. However, it did not shrink during follow-up, and resection was performed. Histologically, the proliferation of the cystic ducts containing eosinophilic secretions and dilated tubules consisting of cuboidal or hobnail-shaped cells were observed.

Clinical discussion: Lactating adenoma, phyllodes tumor, and breast cancer are essential differential diagnoses when the size of breast masses increases rapidly. Ultrasonography is the first choice to examine lactating adenomas. Echogenic bands and pseudocapsules are characteristics of lactating adenomas.

Conclusion: Surgical excision is a notable treatment option when a lactating adenoma exhibits rapid growth or increase in mass, as it could be malignant.

Keywords: Benign breast tumor; Case report; Lactating adenoma; Malignant; Pregnancy.

Fig. 1

Mammogram showing an equal-density lobular mass indicated by the arrows in the upper-outer left breast.

Fig. 2

Ultrasonography showing a circumscribed hypoechoic lobular mass with cystic regions. This mass measured about 60 mm and was located in the upper lateral left breast.

Fig. 3

MRI showing an approximately 65-mm mass in the upper lateral left breast. The solid mass contained cystic regions and contrast enhancement.

Fig. 4

Gross view of the surgical specimen showing a circumscribed brown mass measuring about 60 mm. The mass had many cystic areas exhibiting lactational secretion.

Fig. 5

Microscopic examination of surgical specimen. A and B: Proliferation of cystic ducts containing eosinophilic secretions and tubules consisting of cuboidal or hobnail-shaped cells contacting vacuolated clear cytoplasm.