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Diagnosis in short

Fibroadenoma. H&E stain.

LM abundant (intralobular) stroma usu. white/pale +/-hyalinization, typically paucicellular, compression of glandular elements with perserved myoepithelial cells
Subtypes juvenile, complex, myxoid, cellular, tubular adenoma of the breast
LM DDx phyllodes tumour, sarcoma, pseudoangiomatous stromal hyperplasia, adenomyoepithelioma for tubular adenoma of the breast
Gross well-circumscribed, rubbery, tan/white, +/-lobulated appearance, +/-short slit-like spaces, +/-calcifications
Site breast

Prevalence very common
Radiology typically BIRADS4 - see BIRADS
Prognosis benign
Clin. DDx other breast tumours - esp. phyllodes tumour
Treatment conservative excision

Fibroadenoma, abbreviated FA, is a common benign tumour of the breast.

It is a type of fibroepithelial tumour.


  • Very common benign finding.
  • The pathology is in the stroma; so, the lesion is really a misnomer by the naming rules.
    • It ought to be called adenofibroma (as a few occasionally do[1]), as the glandular component is benign and the stromal component lesional; there is no truth in names in pathology.


  • Local excision -- without a large margin.



  • Well-circumscribed.
  • Rubbery - classic descriptor.
  • Tan/white.
  • +/-Lobulated appearance.
  • +/-Slit-like spaces - short.
  • +/-Calcification.




  • Abundant (intralobular) stroma - most key feature.
    • Stroma is usually:
      • White/pale, i.e. myxoid, on H&E (normal stroma is pink).
        • May be hyalinized (dark pink) if infarcted.
      • Paucicellular - typical.
  • Compression of glandular elements - very commonly seen.
    • Glandular elements have at least two cell layers - epithelial and myoepithelial.


  1. There is stuff about intracanalicular vs. pericanalicular.[4] It is irrelevant; there is no prognostic difference between the two.
  2. Do not comment on the margin - it is irrelevant.





Four variants are described by the Washington Manual:[7]

  1. Juvenile.
  2. Complex.
  3. Myxoid.
  4. Cellular.

Considered a variant of fibroadenoma by many authorities:[8]

Juvenile fibroadenoma

  • As the name suggests, is typically found in younger patients.
  • Classic history: rapid growth.

Features (juvenile variant):[9]

Myxoid fibroadenoma


Cellular fibroadenoma

Features (cellular variant):

  • Cellular.
  • Mitoses.


  • "Cellular" is something that can be subjective. One definition of "cellular" is: "stromal cells are touching one another". Jacobs et al. has a stromal cellularity picture gallery showing mild (rare stromal cells touching), moderate and marked (many stromal cells touching).[10]

Complex fibroadenoma

  • Contain proliferative epithelium which outside and inside a fibroadenoma is associated with an increased risk of malignancy.


  1. Apocrine metaplasia.
  2. Cysts > 3 mm.
  3. Calcification.
  4. Sclerosing adenosis.

Memory devices:

  • FACS: complex fibroadenoma, apocrine metaplasia, calcs & cysts, sclerosing adenosis.
  • CAMS: calcs, apocrine metaplasia, microcysts, sclerosing adenosis.

Tubular adenoma of the breast

  • Considered by many a variant of fibroadenoma.
  • Most present in adults between menarche and menopause.


  • Well circumscribed lesion.
  • Closely packed uniform tubules, lined by a single layer of epithelial cells and an attenuated myoepithelial cell layer.
  • Stroma is generally more sparse than in conventional fibroadenoma


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Right Breast, Lumpectomy:
- Complex fibroadenoma with apocrine metaplasia.
- Negative for carcinoma in situ and negative for malignancy.


The sections show a lesion with a pale mildly cellular stroma, and bland glandular elements. Minimal mitotic activity is present (2 mitosis/10 HPF, where 1 HPF ~ 0.2376 mm*mm). The border is well-circumscribed where seen. The lesion was shelled-out.

No cytologic atypia is present. No leaf-like architecture is present. No stromal overgrowth is seen. No calcifications are evident. No large cysts are seen.

See also


  1. Guinebretière, JM.; Menet, E.; Tardivon, A.; Cherel, P.; Vanel, D. (Apr 2005). "Normal and pathological breast, the histological basis.". Eur J Radiol 54 (1): 6-14. doi:10.1016/j.ejrad.2004.11.020. PMID 15797289.
  2. Mitchell, Richard; Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Aster, Jon (2011). Pocket Companion to Robbins & Cotran Pathologic Basis of Disease (8th ed.). Elsevier Saunders. pp. 550. ISBN 978-1416054542.
  3. O'Malley, Frances P.; Pinder, Sarah E. (2006). Breast Pathology: A Volume in Foundations in Diagnostic Pathology series (1st ed.). Churchill Livingstone. pp. 110. ISBN 978-0443066801.
  4. URL: Accessed on: 16 March 2011.
  5. Sabate, JM.; Clotet, M.; Torrubia, S.; Gomez, A.; Guerrero, R.; de las Heras, P.; Lerma, E. (Oct 2007). "Radiologic evaluation of breast disorders related to pregnancy and lactation.". Radiographics 27 Suppl 1: S101-24. doi:10.1148/rg.27si075505. PMID 18180221.
  6. URL: Accessed on: 15 February 2012.
  7. Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 262. ISBN 978-0781765275.
  8. 8.0 8.1 8.2 O'Malley, Frances P.; Pinder, Sarah E. (2006). Breast Pathology: A Volume in Foundations in Diagnostic Pathology series (1st ed.). Churchill Livingstone. pp. 116. ISBN 978-0443066801.
  9. URL: Accessed on: 3 October 2011.
  10. Jacobs, TW.; Chen, YY.; Guinee, DG.; Holden, JA.; Cha, I.; Bauermeister, DE.; Hashimoto, B.; Wolverton, D. et al. (Sep 2005). "Fibroepithelial lesions with cellular stroma on breast core needle biopsy: are there predictors of outcome on surgical excision?". Am J Clin Pathol 124 (3): 342-54. doi:10.1309/5N2C-4N5X-CB8X-W8JL. PMID 16191502.
  11. URL: Accessed on: 3 October 2011.
  12. Maiorano, E.; Albrizio, M. (Dec 1995). "Tubular adenoma of the breast: an immunohistochemical study of ten cases.". Pathol Res Pract 191 (12): 1222-30. PMID 8927570.