Breast - nonmalignant
Benign tumors / changes
Phyllodes tumor - benign

Author: Hind Nassar, M.D. (see Authors page)

Revised: 10 August 2017, last major update April 2010

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed Search: Benign phyllodes tumor [title] breast

See also: Phyllodes - generalPhyllodes - borderlinePhyllodes - malignant

Cite this page: Nassar, H. Phyllodes tumor - benign. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/breastphyllodesbenign.html. Accessed September 23rd, 2017.
Definition / general
  • Phyllodes features but no / rare mitotic figures, no atypia
Terminology
  • Also called low grade because even histologically benign appearing tumors may have malignant behavior
Clinical features
  • Most (75%) phyllodes tumors are benign
  • May have benign adipose tissue as primary stromal component (lipophyllodes tumor, Arch Pathol Lab Med 1994;118:91)
  • May recur locally but only rare distant metastases
Radiology images

Images hosted on PathOut server:

Mammogram, contributed by Dr. Mark R. Wick

Case reports
Treatment
  • Excision with 1 - 2 cm margins (Mod Pathol 2001;14:185)
  • Breast preservation if possible, particular in young women
Gross description
  • Well circumscribed, firm, gray white cut surface with cleft-like spaces resembling a leaf
  • Variable cysts, hemorrhage, necrosis (more common in larger tumors)
Gross images

Images hosted on PathOut server:

Contributed by Dr. Mark R. Wick



Images hosted on other servers:

Large, well circumscribed tumors


Multiple, polypoid nodules

Well circumscribed with firm consistency

Necrosis, hemorrhage and cystic degeneration

Microscopic (histologic) description
  • Circumscribed pushing border, stromal hypercellularity (particularly next to epithelial elements) and benign glandular elements with intracanalicular pattern but ratio is balanced
  • Stroma resembles fibroblasts and myofibroblasts
  • Epithelial component has luminal epithelial cells resting on myoepithelial layer
  • May exhibit hyperplasia, squamous metaplasia
  • May have clusters of multinucleated giant cells (Arch Pathol Lab Med 1994;118:912)
  • Variable hemorrhage, necrosis, fat, bone, cartilage and skeletal muscle
  • 0 - 4 mitotic figures/10 HPF
  • No atypia
Microscopic (histologic) images

Images hosted on PathOut server:

Low grade, contributed by Dr. Mark R. Wick


Hyperplastic duct surrounded by cellular fibrous stroma

Apocrine hyperplasia

Focal nuclear pleomorphism and mitotic figures

With LCIS

Well circumscribed
tumor with leaf-like
ductal epithelium



Images hosted on other servers:

Hyperplastic ducts surrounded by cellular fibrous stroma

Circumscribed tumor

Leaf-like processes


Adjacent fibroadenoma

Low grade

Cysts containing papillary structures

Low grade phyllodes tumor

PASH-like changes in stroma

Myxoid background


Stroma is hyalinized

Nodular structure

Fibroblastic stromal cells are present

Adenosis-like appearance

Tubular epithelial elements

Epithelial hyperplasia


CD117

CD31

Ki67

Positive stains
Electron microscopy description
  • Fibroblastic features
Molecular / cytogenetics description
Differential diagnosis