Spuriously aggressive features of a lactating adenoma prompting repeated biopsies

Abstract

We present an atypical presentation of a common pregnancy-related breast mass, a lactating adenoma with imaging and pathologic correlation. The patient presented with a rapidly enlarging left breast mass associated with skin changes and severe pain in the perinatal period. Core biopsies were considered discordant, and the patient went on to surgical excision for the definitive diagnosis of an infarcted lactating adenoma. The symptoms of infarction may obscure the diagnosis of common entities and result in additional evaluation.

Giant lactating adenoma

“…It occurs during the third trimester of pregnancy, as well as during breast feeding. 6 In our case, in addition to its unusually large size (more than 10 cm on palpation), this lactating adenoma presented as multiple nodules. Moreover, this lesion had poorly-defined ultrasonographic margins (BI-RADS 5), its growth began in early pregnancy, and contained areas of necrosis and chronic mastitis.…”

“…Biopsy is the current gold standard test used to diagnose lactating adenoma and should not be delayed until after delivery. 6 However, ultrasound (US) and mammography applying the BIRADS classification (Breast Imaging Reporting and Data System) are useful modalities to confirm the need to proceed with tissue sampling. 2,5…”

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

“…Lactating adenoma, fibroadenoma, and lobular hyperplasia with hormonal stimulation are common differential diagnoses for a palpable and mobile breast mass during pregnancy and lactation [4] , [5] . Histologically, lactating adenomas are characterized by the proliferation of acini and mammary ducts, preservation of bilayers of epithelial and myoepithelial cells, and eosinophilic secretions in the lumen [6] , [7] .…”

“…In some cases, lactational secretions appear as a hyperechoic mass on US. The characteristic features of lactating adenoma are the presence of echogenic bands in the form of pathological fibrotic stromal proliferation and echogenic pseudocapsules associated with a compressed thin layer of stroma [6] . Additionally, MMG and MRI are sometimes performed on women with lactating adenoma.…”

“…On MMG, a lactating adenoma is usually seen as a circumscribed lobulated mass without calcification, with a density equal to or less than that of the mammary gland [14] , [15] . It is difficult to detect lactating adenomas in women during pregnancy or lactation because of the normally increasing density of the mammary gland [6] . MRI often shows lactating adenoma as a homogeneous and circumscribed mass with contrast enhancement [16] .…”