Breast nonmalignant
Nonneoplastic changes
Lactating adenoma


Topic Completed: 21 April 2020

Minor changes: 21 April 2020

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PubMed Search: Lactating adenoma [title] breast

Samaneh A. Motanagh, M.D.
Kristen E. Muller, D.O.
Page views in 2019: 10,703
Page views in 2020 to date: 3,994
Cite this page: Motanagh S, Muller K. Lactating adenoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/breastlactatingadenoma.html. Accessed May 28th, 2020.
Definition / general
  • Well circumscribed mass, arising during or shortly after pregnancy, composed of cuboidal cells with actively secreting, closely packed glands
Essential features
  • Most prevalent breast lesion in pregnant women and during postpartum period
  • Must be distinguished from carcinoma, as breast cancer is the second most common malignancy during pregnancy
  • Age range (19 - 34 years), female
  • Benign, slow growing
  • Unknown capability of malignant transformation
Terminology
  • Adenomatous lactational hyperplasia, nodular lactational hyperplasia (not recommended by WHO)
ICD coding
  • ICD-0: 8204/0 - Lactating adenoma
  • ICD-10: D24 - Benign neoplasm of breast
  • ICD-11: 2F30.1 - Lactating adenoma of breast
  • ICD-11: XH0W31 - Lactating adenoma
Epidemiology
  • 19 - 34 years, female, predominantly in third decade of life
  • Most prevalent breast lesion in pregnant women (mostly third trimester) and during postpartum period (puerperium)
Sites
Pathophysiology
  • Unknown if de novo neoplasm or hyperplastic condition
  • Some postulate may arise in a pre-existing adenoma (tubular adenoma, fibroadenoma) with superimposed lactational changes; however, lack of MED12 exon 2 mutations, frequently found in fibroadenomas, does not support this theory (Genes Chromosomes Cancer 2017;56:11)
  • Increase in serum estrogen, progesterone and prolactin
Clinical features
  • Painless, soft, palpable, solid, mobile discrete mass
  • May be bilateral and multifocal
  • Infarction may lead to pain, tenderness and rapid enlargement
Diagnosis
Radiology description
Radiology images

Contributed by Kristen E. Muller, D.O.

Well circumscribed hypoechoic mass

Hypoechoic mass with hypervascularity

Prognostic factors
  • Slow growing, spontaneous regression
  • No progression to cancer on follow up studies
  • Unknown if capable of carcinogenesis or risk factor
  • Coexistence of lactating adenoma with breast malignancy reported (Indian J Cancer 2015;52:585, J Clin Pathol 2005;58:87)
Case reports
Treatment
  • Observation for slow growing
  • Many spontaneously regress after termination of breastfeeding
  • Enucleation in cases that warrant excision (enlarging, worrisome clinical or histologic features)
Clinical images

Images hosted on other servers:

Large mass

Gross description
Gross images

Contributed by Dr. Mark R. Wick

Lactating adenoma



Images hosted on other servers:

Well circumscribed mass

Microscopic (histologic) description
  • Well circumscribed proliferation of hyperplastic closely packed lobules with both epithelial and myoepithelial cell layers separated by thin, delicate connective tissue
  • Glands lined by actively secreting cuboidal or hobnail shaped cells with small round nuclei and granular to clear vacuolated cytoplasm
  • Variably prominent small, pinpoint nucleoli may be seen but cells lack cytologic atypia
  • Occasional mitoses may be seen
  • Resembles pregnancy-like (pseudolactational) changes
  • May resemble fibroadenoma or tubular adenoma with lactational change microscopically
Microscopic (histologic) images

Contributed by Kristen E. Muller, D.O.

Lactating adenoma biopsy

Vacuolated cytoplasm

Hypersecretory features


Delicate stroma

Prominent hobnailing

Psammomatous calcification

Virtual slides

Images hosted on other servers:

Lactating adenoma

Cytology description
  • Loose cohesive clusters of monomorphic cells or single cells
  • Cells contain foamy to finely vacuolated cytoplasm, round uniform nuclei with fine chromatin and small nucleoli (J Clin Diagn Res 2013;7:2417)
  • Background of foamy material
Cytology images

Contributed by Dr. Mark R. Wick

FNAB



Images hosted on other servers:

Increased lobular size

Cytoplasmic vacuoles and background foamy material

Positive stains
Molecular / cytogenetics description
  • 50 gene NGS panel showed no mutations in three lactating adenomas in one series, including MED12 exon 2 mutations (frequently seen in fibroadenomas) (Genes Chromosomes Cancer 2017;56:11)
Sample pathology report
  • Right breast mass, needle biopsy:
    • Breast tissue with lactational change / lactating adenoma
    • Microcalcifications associated with lactational change / lactating adenoma
Differential diagnosis
  • Lobular hyperplasia (normal physiologic event in pregnancy):
    • Not a well defined mass
  • Delayed involution of lactation:
    • Not a well defined mass
    • Hyperplastic and involuting lobules
    • Neutrophils, macrophages and lymphocytes in background
    • More frequently associated with calcifications
  • Fibroadenoma with secretory activity:
    • Fibroepithelial architecture
    • Prominent stroma
    • Focal, not diffuse, proliferation of cells with secretory activity
Board review style question #1
Which of the following is correct for the entity pictured from this breast biopsy from a 27 year old pregnant woman?



  1. Frequently shows a prominent stromal component similar to fibroepithelial lesions
  2. Histologically composed of closely packed glands lined by actively secreting cuboidal or hobnail shaped cells
  3. Never develops in ectopic breast tissue along milk line
  4. The glands lack a myoepithelial cell layer
  5. Third most prevalent breast lesion in pregnant women
Board review answer #1
B. Histologically composed of closely packed glands lined by actively secreting cuboidal or hobnail shaped cells

Reference: Lactating adenoma

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Board review style question #2
What is the most common breast lesion in pregnant and lactating women?

  1. Adenomyoepithelioma
  2. Atypical ductal hyperplasia
  3. Fibroadenoma
  4. Invasive ductal carcinoma
  5. Lactating adenoma
Board review answer #2
E. Lactating adenoma

Reference: Lactating adenoma

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