Fibroepithelial tumor

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Author: Mikael Häggström [note 1]

Gross examination

As per:

or mastectomy.

Microscopic evaluation

Fibroadenoma

Characteristics of fibroepithelial tumor

Biplastic, having proliferation of both stromal and epithelial components,[note 2] arranged into either a pericanalicular pattern (stromal proliferation around epithelial structures), or an intracanalicular pattern (stromal proliferation compressing the epithelial structures into clefts).

Characteristics of fibroadenoma

Fibroadenomas characteristically display hypovascular stroma compared to malignant tumors.[1][2][3] Furthermore, the epithelial proliferation appears in a single terminal ductal unit and has duct-like spaces surrounded by a fibroblastic stroma. The basement membrane is intact.[4]

Characteristics of phyllodes tumor

Benign phyllodes tumor

In contrast to fibroadenomas, phyllodes tumors display a leaf-like architecture, and an increased stromal cellularity.[5] In needle biopsy specimens, phyllodes tumors can be diagnosed in a fibroepithelial tumor if there is prominent mitotic activity of ≥3 per 10 high power fields, or the finding of 3 or more of the following characteristic histologic features:[5]

  • Stromal overgrowth
  • Fat infiltration
  • Stromal fragmentation
  • Subepithelial stromal condensation
  • Stromal nuclear pleomorphism

Further workup

After diagnosing a fibroepithelial tumor, classify it as benign, borderline or malignant:[6]

Benign Borderline Malignant
Stromal atypia Mild Moderate Marked
Stromal cellularity Mildly increased, can be focal Moderately increased, can be focal Markedly and diffusely increased
Stromal overgrowth* Absent Absent or very focal Present
Mitotic count < 5/10 HPF or < 2.5/mm² 5 - 9/10 HPF or 2.5 - < 5/mm² ≥ 10/10 HPF or ≥ 5/mm²
Tumor border Well defined Well defined or focally permeative Diffusely permeative
Malignant heterologous elements Absent Absent Presence directly upgrades to malignant category**
* Stromal overgrowth can be defined as absence of epithelial elements containing stroma only in 1 low power field.
**Malignant categories include chondrosarcoma, liposarcoma (except well differentiated liposarcoma), osteosarcoma, rhabdomyosarcoma, angiosarcoma and leiomyosarcoma

Also, exclude another type of breast cancer, which may arise within it,[7] possibly being:

For borderline and malignant phyllodes tumors, measure the distance from the tumor to the closest surgical margin. However, such measure is not necessary for benign phyllodes tumor.[8]

Microscopic report

If, even after consultation, it is not clear whether a tumor is a fibroadenoma or phyllodes tumor, then it can be reported as a cellular fibroepithelial lesion or a fibroepithelial neoplasm.

A phyllodes tumor warrants a comment whether margins are positive or negative for tumor, whereas fibroadenoma does not need such comment.

Example report of fibroadenoma:

Right breast, lumpectomy:

Fibroadenoma.
Negative for atypia or malignancy.

Notes

  1. For a full list of contributors, see article history. Creators of images are attributed at the image description pages, seen by clicking on the images. See Patholines:Authorship for details.
  2. The proliferation of two histological components is called "biplasia", from Latin bis (“twice”) and -plasia (“formation”), or "biphasic proliferation" (although the latter may refer to proliferation that has two chronological phases).

Main page

References

  1. Tavassoli, F.A., ed (2003). World Health Organization Classification of Tumours: Pathology & Genetics: Tumours of the breast and female genital organs . Lyon: IARC Press. ISBN 978-92-832-2412-9. 
  2. Jaya Ruth Asirvatham, M.B.B.S., Carlos C. Diez Freire, M.D., Cansu Karakas, M.D., Belinda Lategan, M.D., Nat Pernick, M.D., Emily S. Reisenbichler, M.D., Monika Roychowdhury, M.D., Mary Ann Gimenez Sanders, M.D, Ph.D., Gary Tozbikian, M.D., Hind Warzecha, M.D. Senior Authors: Julie M. Jorns, M.D., Shahla Masood. Breast nonmalignant, Fibroepithelial neoplasms, Fibroadenoma. Retrieved on 2019-11-04. Revised: 31 October 2019
  3. Rosen, PP. (2009). Rosen's Breast Pathology (3rd ed.). ISBN 978-0-7817-7137-5. 
  4. . Fibroadenoma of the breast.
  5. 5.0 5.1 Gary Tozbikian, M.D.. Breast - Fibroepithelial tumors - Fibroadenoma. Last author update: 19 July 2021. Last staff update: 22 July 2021
  6. Authors: Joshua J.X. Li, M.B.Ch.B., Gary M. Tse, M.B.B.S.. Breast - Fibroepithelial tumors - Phyllodes tumor. Pathology Outlines. Last author update: 2 December 2020. Last staff update: 11 January 2023
  7. Richard L Kempson MD, Robert V Rouse MD. Fibroadenoma of the Breast. Stanford University School of Medicine. May 27, 2006
  8. Cowan ML, Argani P, Cimino-Mathews A (2016). "Benign and low-grade fibroepithelial neoplasms of the breast have low recurrence rate after positive surgical margins. ". Mod Pathol 29 (3): 259-65. doi:10.1038/modpathol.2015.157. PMID 26743469. Archived from the original. . 

Image sources