TABLE 5.
Histological classification of breast tumours according to the fifth edition of the WHO classification (40).
| Tumour group | Name | ICD-0 | ICD-11 |
|---|---|---|---|
| EPITHELIAL TUMOURS | |||
| Benign epithelial proliferations and precursors | Normal (typical) ductal hyperplasia | GB20.Y | |
| Columnar cell lesions, including atypical columnar cell transformation (FEA, flat epithelial atypia) | GB20.Y | ||
| Atypical ductal hyperplasia (ADH) | GB20.Y | ||
| Adenosis, benign sclerosing lesions | Sclerosing adenosis | GB20.Y | |
| Apocrine adenoma | 8401/0 | 2F30&XH6YZ9 | |
| Microglandular adenosis | GB20.Y | ||
| Radial scar/Complex sclerosing lesion | GB20.Y | ||
| Adenomas | Tubular adenoma | 8211/0 | 2F30.0&XH7SYZ9 |
| Lactating adenoma | 8204/0 | 2F30.1&XH0W31 | |
| Ductal adenoma | 8503/0 | 2F30.2&XH4LZ4 | |
| Epithelial-myoepithelial tumours | Pleomorphic adenoma | 8940/0 | 2F30.Y&XH2KC1 |
| Adenomyoepithelioma NOS | 8983/0 | 2F30.Y&XH2V57 | |
| Adenomyoepithelioma with carcinoma | 8983/3 | 2C6Y&XH7TL5 | |
| Epithelial-myoepithelial carcinoma | 8562/3 | ||
| Papillary neoplasms | Intraductal papilloma | 8503/0 | 2F30.2&XH4LZ4 |
| Papillary ductal carcinoma in situ | 8503/2 | 2E65.2&XH4V32 | |
| Encapsulated papillary carcinoma | 8504/2 | 2E65.Y&XH9XV2 | |
| Encapsulated papillary carcinoma with invasion | 8504/3 | 2C6Y&XH0GT6 | |
| Solid papillary carcinoma in situ | 8509/2 | 2E65.Y&XH0134 | |
| Solid papillary carcinoma with invasion | 8509/3 | 2C64 | |
| Invasive papillary carcinoma | 8503/3 | 2C60&XH8JR8 | |
| Non-invasive lobular neoplasia | Atypical lobular hyperplasia (ALH) | ||
| Lobular carcinoma in situ (LCIS), NOS | 8520/2 | 2E65.0&XH6EH0 | |
| Classical LCIS | |||
| Florid LCIS | |||
| Pleomorphic LCIS | 8519/2 | ||
| Ductal carcinoma in situ (DCIS) | Intraductal breast carcinoma, NOS | 8500/2 | 2E65.2cXH4V32 |
| Invasive breast carcinoma | Invasive carcinoma, NST | 8500/3 | 2C61.0&XH7KH3 |
| Microinvasive carcinoma | 2C61.0 | ||
| Invasive lobular carcinoma | 8520/3 | 2C61.1&XH2XR3 | |
| Tubular carcinoma | 8211/3 | 2C60&XH4TA4 | |
| Cribriform carcinoma | 8201/3 | 2C60&XH1YZ3 | |
| Mucinous carcinoma | 8480/3 | 2C60&XH1S75 | |
| Mucinous cystadenocarcinoma | 8470/3 | 2C60&XH1390 | |
| Invasive micropapillary carcinoma | 8507/3 | 2C60&XH9C56 | |
| Carcinoma with apocrine differentiation | 8401/3 | 2C61&XH4GA3 | |
| Metaplastic carcinoma | 8575/3 | 2C6Y&XHORD4 | |
| Rare and salivary gland type tumours | Acinic cell carcinoma | 8550/3 | 2C60&XH3PG9 |
| Adenoid cystic carcinoma (ACC) | 8200/3 | 2C60&XH4302 | |
| Secretory carcinoma | 8502/3 | 2C60&XH44J4 | |
| Mucoepidermoid carcinoma | 8430/3 | 2C60&XH1J36 | |
| Polymorphic adenocarcinoma | 8525/3 | 2C60&XH5SD5 | |
| Tall cell carcinoma with reversed polarity | 8509/3 | 2C6Y | |
| Neuroendocrine neoplasia | Neuroendocrine tumour NOS | 8240/3 | 2C6Y&XH9LV8 |
| Neuroendocrine tumour Grade 1 | 8240/3 | ||
| Neuroendocrine tumour Grade 2 a | 8249/3 | ||
| Neuroendocrine carcinoma NOS | 8246/3 | 2C6Y&XH0U20 | |
| Neuroendocrine carcinoma, small cell | 8041/3 | 2C6Y&XH9SY0 | |
| Neuroendocrine carcinoma, large cell | 8013/3 | 2C6Y&XH0NL5 | |
| FIBROEPITHELIAL TUMOURS, HAMARTOMAS | Hamartoma | ||
| Fibroadenoma NOS | 9010/0 | 2F30.5&XH9HE2 | |
| Phyllodes tumour NOS | 9020/1 | ||
| Phyllodes tumour, benign | 9020/0 | 2F30.3&XH50P7 | |
| Phyllodes tumour, borderline | 9020/1 | 2F75&XH5NK4 | |
| Phyllodes tumour, malignant | 9020/3 | 2C63&XH8HJ7 | |
| NIPPLE TUMOURS | Syringomatous tumour | 8407/0 | 2F30.Y&XH9GB7 |
| Nipple adenoma | 8506/0 | 2F30.Y&XH7GN3 | |
| Paget’s disease | 8540/3 | 2E65.5&XH3E21 | |
| MESENCHYMAL TUMOURS | |||
| Vascular tumours | Haemangioma NOS | 9120/0 | 2F30.Y&XH5AW4 |
| Angiomatosis | 2E81.0Z | ||
| Common angiomatosis | |||
| Capillary angiomatosis | |||
| Atypical vascular lesions | 9126/0 | ||
| Postradiation angiosarcoma of the breast | 9120/3 | 2B56.2&XH6264 | |
| Primary angiosarcoma of the breast | 9120/3 | 2B56.2&XH6264 | |
| Fibroblastic/myofibroblastic tumours | Nodular fasciitis | 8828/0 | 2F30.Y&XH5LM1 |
| Myofibroblastoma | 8825/0 | 2F30.Y&XH8JB0 | |
| Desmoid fibromatosis | 8821/1 | 2F75&XH13Z3 | |
| Inflammatory myofibroblastic tumour | 8825/1 | 2F30.Y&XH66Z0 | |
| Peripheral nerve sheath tumour | Schwannoma NOS | 9560/0 | 2F30.Y&XH98Z3 |
| Neurofibroma NOS | 9540/0 | 2F30.Y&XH87J5 | |
| Granular cell tumour | 9580/0 | 2F30.Y&XH09A9 | |
| Granular cell tumour, malignant | 9580/3 | ||
| Tumours of smooth muscle origin | Leiomyoma NOS | 8890/0 | 2F30.Y&XH4CY6 |
| Leiomyosarcoma NOS | 8890/3 | 2C6Y&XH7ED4 | |
| Adipose tissue tumours | Lipoma NOS | 8850/0 | 2F30.Y&XH1PL8 |
| Angiolipoma NOS | 8861/0 | 2F30.Y&XH3C77 | |
| Liposarcoma NOS | 8850/3 | 2C6Y&XH2J05 | |
| Other mesenchymal tumours and tumour-like lesions | Pseudoangiomatous stromal hyperplasia | GB20.Y | |
| HEMATOLYMPHOID TUMOURS | Lymphoma | ||
| MALT lymphoma | 9699/3 | 2A85.3 | |
| Follicular lymphoma (NOS) | 9690/3 | 2A80.Z | |
| Diffuse large B-cell lymphoma NOS | 9680/3 | 2A81.Z | |
| Burkitt lymphoma NOS/Acute leukaemia, Burkitt type | 9687/3 | 2A85.6 | |
| Anaplastic large cell lymphoma associated with breast implant | 9715/3 | 2A90.B | |
| MALE BREAST TUMOURS | Epithelial tumours | ||
| Gynaecomastia | GB22 | ||
| Carcinoma in situ NOS | 8500/2 | ||
| DCIS | 2E65.2&XH4V32 | ||
| LCIS | 2E65.0&XH6EH0 | ||
| Paget’s disease of nipple | |||
| Invasive carcinoma, NST | 8500/3 | 2C61.0&XH7KH3 | |
| BREAST METASTASES | 2E0Y&XA12C1 | ||
| GENETIC TUMOUR SYNDROMES | BRCA1/2-associated hereditary breast and-ovarian cancer syndrome | 2C65 | |
| Cowden syndrome | LD2D.Y | ||
| Ataxia-telangiectasia | 4A01.31 | ||
| Li–Fraumeni syndrome, TP53-associated | |||
| Li–Fraumeni syndrome, CHEK2-associated | |||
| CDH1-associated breast cancer | |||
| PALB2-associated breast cancer | |||
| Peutz–Jeghers syndrome | LD2D.0 | ||
| Neurofibromatosis type 1 | LD2D.10 | ||
| Polygenic component of breast cancer susceptibility | |||
a
The term “neuroendocrine tumour (NET) Grade 3” is not included in the WHO publication, although the principle was to harmonize the classification of neuroendocrine neoplasms with that used for other organs. Breast NET grade is determined according to the Nottingham grading scheme, which is different from the NET grading system used for other organs; Grade 3 has not been defined. Breast NET is defined as a malignant tumour. Breast NET is rare, so the prognosis of tumours classified in this category is unknown. (Altogether, the classification of tumours into NET, NEC or NST carcinoma with neuroendocrine differentiation is somewhat controversial, these tumours require individual and multidisciplinary approaches to avoid improper management. NOS, not otherwise specified; NST, no special type.