WHO classification of breast tumors

Breast malignant, males, children
Breast cancer
WHO classification of breast tumors

Author: Belinda Lategan, M.D. (see Authors page)

Revised: 20 October 2016, last major update September 2014

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: WHO classification of breast tumors

Table of Contents

Definition / general | Additional references

Cite this page: WHO classification of breast tumors. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/breastmalignantwhoclassification.html. Accessed July 14th, 2017.

Definition / general

Updated 2012 WHO WHO Classification of Tumors of the Breast
- First edition to separate breast tumors from tumors of female genital organs
- Takes into account newer developments in the understanding of specific lesions
- Includes staging recommendations in more contentious situations i.e. pT- stage encapsulated papillary carcinoma as Tis as opposed to based on size
- Updated information on molecular pathology, expression profiling and molecular classification of breast tumors; however, focus remains on morphologic classification
- Updates on prognostic markers
  - Does not reflect most recent 2013 ASCO / CAP recommendations for interpretation of HER2 tests

2012 WHO Classification of Tumors of the Breast

Epithelial tumors
- Microinvasive carcinoma
Invasive breast carcinoma
- Invasive carcinoma of no special type (NST)
  - Pleomorphic carcinoma
  - Carcinoma with osteoclast like stromal giant cells
  - Carcinoma with choriocarcinomatous features
  - Carcinoma with melanotic features
- Invasive lobular carcinoma
  - Classic lobular carcinoma
  - Solid lobular carcinoma
  - Alveolar lobular carcinoma
  - Pleomorphic lobular carcinoma
  - Tubulolobular carcinoma
  - Mixed lobular carcinoma
- Tubular carcinoma
- Cribiform carcinoma
- Mucinous carcinoma
- Carcinoma with medullary features
  - Medullary carcinoma
  - Atypical medullary carcinoma
  - Invasive carcinoma NST with medullary features
- Carcinoma with apocrine differentiation
- Carcinoma with signet ring differentiation
- Invasive micropapillary carcinoma
- Metaplastic carcinoma of no special type
  - Low-grade adenosquamous carcinoma
  - Fibromatosis like metaplastic carcinoma
  - Squamous cells carcinoma
  - Spindle cell carcinoma
  - Metaplastic carcinoma with mesenchymal differentiation
    - Chondroid differentiation
    - Osseous differentiation
    - Other types of mesenchymal differentiation
  - Mixed metaplastic carcinoma
  - Myoepithelial carcinoma
- Rare types
  - Carcinoma with neuroendocrine features
    - Neuroendocrine tumor, well differentiated
    - Neuroendocrine carcinoma, poorly differentiated (small cell carcinoma)
    - Carcinoma with neuroendocrine differentiation
  - Secretory carcinoma
  - Invasive papillary carcinoma
  - Acinic cell carcinoma
  - Mucoepidermoid carcinoma
  - Polymorphous carcinoma
  - Oncocytic carcinoma
  - Lipid rich carcinoma
  - Glycogen rich clear cell carcinoma
  - Sebaceous carcinoma
  - Salivary gland / skin adnexal type tumors
    - Cylindroma
    - Clear cell hidradenoma
Epithelial-myoepithelial tumors
- Pleomorphic adenoma
- Adenomyoepithelioma
  - Adenomyoepithelioma with carcinoma
- Adenoid cystic carcinoma
Precursor lesions
- Ductal carcinoma in situ
- Lobular neoplasia
  - Lobular carcinoma in situ
    - Classic lobular carcinoma in situ
    - Pleomorphic lobular carcinoma in situ
  - Atypical lobular hyperplasia
Intraductal proliferative lesions
- Usual ductal hyperplasia
- Columnar cell lesions including flat epithelial atypia
- Atypical ductal hyperplasia
Papillary lesions
- Intraductal papilloma
  - Intraductal papilloma with atypical hyperplasia
  - Intraductal papilloma with ductal carcinoma in sit
  - Intraductal papilloma with lobular carcinoma in situ
- Intraductal papillary carcinoma
- Encapsulated papillary carcinoma
  - Encapsulated papillary carcinoma with invasion
- Solid papillary carcinoma
  - In situ
  - Invasive
Benign epithelial proliferations
- Sclerosing adenosis
- Apocrine adenosis
- Microglandular adenosis
- Radial scar / complex sclerosing lesion
- Adenomas
  - Tubular adenoma
  - Lactating adenoma
  - Apocrine adenoma
  - Ductal adenoma
Mesenchymal tumors
- Nodular fasciitis
- Myofibroblastoma
- Desmoids type fibromatosis
- Inflammatory myofibroblastic tumor
- Benign vascular lesions
  - Haemangioma
  - Angiomatosis
  - Atypical vascular lesions
- Pseudoangiomatous stromal hyperplasia
- Granular cell tumor
- Benign peripheral nerve sheath tumors
  - Neurofibroma
  - Schwannoma
- Lipoma
  - Angiolipoma
- Liposarcoma
- Angiosarcoma
- Rhabdomyosarcoma
- Osteosarcoma
- Leiomyoma
- Leiomyosarcoma
Fibroepithelial tumors
- Fibroadenoma
- Phyllodes tumor
  - Benign
  - Borderline
  - Malignant
  - Periductal stromal tumor, low grade
- Hamartoma
Tumors of the nipple
- Nipple adenoma
- Syringomatous adenoma
- Paget disease of the nipple
Malignant lymphoma
- Diffuse large B cell lymphoma
- Burkitt lymphoma
- T cell lymphoma
  - Anaplastic large cell lymphoma, ALK negative
- Extranodal marginal-zone B cell lymphoma of MALT-type
- Follicular lymphoma
Metastatic tumors
Tumors of the male breast
- Gynaecomastia
- Carcinoma
  - Invasive carcinoma
    - In situ carcinoma
Clinical patterns
- Inflammatory carcinoma
- Bilateral breast carcinoma

Additional references

Lakhani: WHO Classification of Tumors of the Breast, 4th Edition, 2012, Breast Care (Basel) 2013;8:149, WebMicroscope 2003 Classification Table, Tavassoli: Tumours of the Breast and Female Genital Organs, WHO, 2003, Wikipedia - Breast cancer classification