IS Case 425: Lactating adenoma

Sara Ann Majewski, MD

University of Rochester

Imaging Sciences URMC 2010
Publication Date: 2010-08-27


A 6-month pregnant, 31-year-old, female noticed a palpable lump in her left breast approximately one month ago which has not changed in size.


Ultrasound demonstrated a hypoechoic mass.


Lactating adenoma


Lactating adenoma is a benign breast lesion believed to be a response to physiologic changes in pregnancy and lactation. It is made up of lobules demonstrating secretory hyperplasia (similar to surrounding breast tissue) separated connective tissue microscopically. Lactational adenomas are well circumscribed but nonencapsulated. Most involute after pregnancy and lactation.

Lactating adenomas are radiologically indistinguishable from fibroadenomas. They demonstrate mammographically radiolucent or US hyperechoic regions secondary to fat content of milk secondary to lactational hyperplasia. Lactating adenomas are well defined, but usually have no capsule. Some adenomas can be confused with malignancy, demonstrating irregular masses, microlobulated margins, posterior acoustic shadowing, hypoechogenicity and heteroechogenicity. Some of these features may be due to infarction, as occurs in fibroadenomas.


  1. Sabate J, Clotet M, Torrubia S, et al. Radiologic evaluation of breast disorders related to pregnancy and lactation. Radiographics. 2007 Oct;27 Suppl 1:S101-24. PMID: 18180221
  2. Sumkin JH, Perrone AM, Harris KM, et al. Lactating adenoma: US features and literature review. Radiology. 1998 Jan;206(1):271-4. PMID: 9423682

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