Breast malignant
Breast cancer
WHO classification of breast tumors


Topic Completed: 14 January 2020

Revised: 21 January 2020

Copyright: 2012-2020, PathologyOutlines.com, Inc.

PubMed Search: WHO classification breast tumors [title]

Indu Agarwal M.D.
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Cite this page: Agarwal I, Blanco L. WHO classification of breast tumors. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/breastmalignantwhoclassification.html. Accessed January 22nd, 2020.
Definition / general
  • Updated 2012 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
    • Covers not only invasive breast cancers but also precursor lesions, benign epithelial and mesenchymal neoplasms
    • Adopted the TNM definition of the UICC / AJCC for microinvasion (≤ 0.1 cm) (Neth J Surg 1987;39:153)
    • Includes pT classification recommendations in more contentious situations, i.e. pT for encapsulated papillary carcinoma is pTis 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
    • Other notable changes:
      • Recommendation to use the term "invasive carcinoma, no special type (NST)" instead of "invasive ductal carcinoma, not otherwise specified (NOS)" (Neth J Surg 1987;39:153)
      • Recommends abandoning the term "medullary carcinoma" and using the term "carcinoma with medullary features" (Neth J Surg 1987;39:153)
      • Term “intracystic papillary carcinomas” changed to “encapsulated papillary carcinoma” (Neth J Surg 1987;39:153)
Microscopic (histologic) images

Contributed by Indu Agarwal M.D. and Mirna B. Podoll, M.D.
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DCIS

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LCIS, classic type

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Invasive ductal carcinoma

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Invasive lobular carcinoma


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Metastatic lobular carcinoma in lymph node

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Highlighted by AE1 / AE3

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Metaplastic carcinoma


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Encapsulated papillary carcinoma

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Adenoid cystic carcinoma

2012 WHO classification of tumors of the breast
  • Epithelial tumors
    • Microinvasive carcinoma

  • Invasive breast carcinoma
    • Invasive carcinoma of no special type (NST), 8500/3
      • Pleomorphic carcinoma, 8022/3
      • Carcinoma with osteoclast-like stromal giant cells, 8035/3
      • Carcinoma with choriocarcinomatous features
      • Carcinoma with melanotic features
    • Invasive lobular carcinoma, 8520/3
      • Classic lobular carcinoma
      • Solid lobular carcinoma
      • Alveolar lobular carcinoma
      • Pleomorphic lobular carcinoma
      • Tubulolobular carcinoma
      • Mixed lobular carcinoma
    • Tubular carcinoma, 8211/3
    • Cribriform carcinoma, 8201/3
    • Mucinous carcinoma, 8480/3
    • Carcinoma with medullary features
      • Medullary carcinoma, 8510/3
      • Atypical medullary carcinoma, 8513/3
      • Invasive carcinoma NST with medullary features, 8500/3
    • Carcinoma with apocrine differentiation
    • Carcinoma with signet ring differentiation
    • Invasive micropapillary carcinoma, 8507/3
    • Metaplastic carcinoma of no special type, 8575/3
      • Low grade adenosquamous carcinoma, 8570/3
      • Fibromatosis-like metaplastic carcinoma, 8572/3
      • Squamous cells carcinoma, 8070/3
      • Spindle cell carcinoma, 8032/3
      • Metaplastic carcinoma with mesenchymal differentiation
        • Chondroid differentiation, 8571/3
        • Osseous differentiation, 8571/3
        • Other types of mesenchymal differentiation, 8575/3
      • Mixed metaplastic carcinoma, 8575/3
      • Myoepithelial carcinoma, 8982/3
    • Rare types
      • Carcinoma with neuroendocrine features
        • Neuroendocrine tumor, well differentiated, 8246/3
        • Neuroendocrine carcinoma, poorly differentiated (small cell carcinoma), 8041/3
        • Carcinoma with neuroendocrine differentiation, 8574/3
      • Secretory carcinoma, 8502/3
      • Invasive papillary carcinoma, 8503/3
      • Acinic cell carcinoma, 8550/3
      • Mucoepidermoid carcinoma, 8430/3
      • Polymorphous carcinoma, 8525/3
      • Oncocytic carcinoma, 8290/3
      • Lipid rich carcinoma, 8314/3
      • Glycogen rich clear cell carcinoma, 8315/3
      • Sebaceous carcinoma, 8410/3
      • Salivary gland / skin adnexal type tumors
        • Cylindroma, 8200/0
        • Clear cell hidradenoma, 8402/0

  • Epithelial - myoepithelial tumors
    • Pleomorphic adenoma, 8940/0
    • Adenomyoepithelioma, 8983/0
      • Adenomyoepithelioma with carcinoma, 8983/3
    • Adenoid cystic carcinoma, 8200/3

  • Precursor lesions
    • Ductal carcinoma in situ, 8500/2
    • Lobular neoplasia
      • Lobular carcinoma in situ
        • Classic lobular carcinoma in situ, 8520/2
        • Pleomorphic lobular carcinoma in situ, 8519/2
      • Atypical lobular hyperplasia

  • Intraductal proliferative lesions
    • Usual ductal hyperplasia
    • Columnar cell lesions including flat epithelial atypia
    • Atypical ductal hyperplasia

  • Papillary lesions
    • Intraductal papilloma, 8503/0
      • Intraductal papilloma with atypical hyperplasia, 8503/0
      • Intraductal papilloma with ductal carcinoma in situ, 8503/2
      • Intraductal papilloma with lobular carcinoma in situ, 8520/2
    • Intraductal papillary carcinoma, 8503/2
    • Encapsulated papillary carcinoma, 8504/2
      • Encapsulated papillary carcinoma with invasion, 8504/3
    • Solid papillary carcinoma
      • In situ, 8509/2
      • Invasive, 8509/3

  • Benign epithelial proliferations
    • Sclerosing adenosis
    • Apocrine adenosis
    • Microglandular adenosis
    • Radial scar / complex sclerosing lesion
    • Adenomas
      • Tubular adenoma, 8211/0
      • Lactating adenoma, 8204/0
      • Apocrine adenoma, 8401/0
      • Ductal adenoma, 8503/0

  • Mesenchymal tumors
    • Nodular fasciitis, 8828/0
    • Myofibroblastoma, 8825/0
    • Desmoid type fibromatosis, 8821/1
    • Inflammatory myofibroblastic tumor, 8825/1
    • Benign vascular lesions
      • Hemangioma, 9120/0
      • Angiomatosis
      • Atypical vascular lesions
    • Pseudoangiomatous stromal hyperplasia
    • Granular cell tumor, 9580/0
    • Benign peripheral nerve sheath tumors
      • Neurofibroma, 9540/0
      • Schwannoma, 9560/0
    • Lipoma, 8850/0
      • Angiolipoma, 8861/0
    • Liposarcoma, 8850/3
    • Angiosarcoma, 9120/3
    • Rhabdomyosarcoma, 8900/3
    • Osteosarcoma, 9180/3
    • Leiomyoma, 8890/0
    • Leiomyosarcoma, 8890/3

  • Fibroepithelial tumors
    • Fibroadenoma, 9010/0
    • Phyllodes tumor, 9020/1
      • Benign, 9020/0
      • Borderline, 9020/1
      • Malignant, 9020/3
      • Periductal stromal tumor, low grade, 9020/3
    • Hamartoma

  • Tumors of the nipple
    • Nipple adenoma, 8506/0
    • Syringomatous adenoma, 8407/0
    • Paget disease of the nipple, 8540/3

  • Malignant lymphoma
    • Diffuse large B cell lymphoma, 9680/3
    • Burkitt lymphoma, 9687/3
    • T cell lymphoma
      • Anaplastic large cell lymphoma, ALK negative, 9702/3
    • Extranodal marginal zone B cell lymphoma of MALT type, 9699/3
    • Follicular lymphoma, 9690/3

  • Metastatic tumors
  • Tumors of the male breast
    • Gynecomastia
    • Carcinoma
      • Invasive carcinoma, 8500/3
      • In situ carcinoma, 8500/2

  • Clinical patterns
    • Inflammatory carcinoma, 8530/3
    • Bilateral breast carcinoma
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