World Health Organization 5thed Classification of Tumours of the Breast SG Jordan MD and SB O’Connor MD Departments of Radiology and Pathology and Laboratory Medicine

Introduction Invasive Breast Carcinoma (IBC) Fibroepithelial tumours and hamartomas Genetic tumour syndromes The World Health Organization (WHO) establishes the standard Breast Cancer 2019 Fibroadenoma NEW! in this WHO edition for histopathologic diagnoses, defining diagnoses on a per organ Phyllodes tumour: Benign, Borderline, Malignant system basis. Estimated new cases and deaths from breast cancer in the US Hamartoma is a section delineating the familial predisposition to breast cancer, specifically the established and The most recent classification of breast tumors is the 5th edition New cases: 268,600 15.2 % of all new cancer cases emergent genes that are a source of discussion. published in November 2019. The publication reflects the views Deaths: 41,760 6.9 % of all cancer deaths BRCA1 and BRCA2 are well-established, and of the WHO Classification of Tumours Editorial Board that increasingly PALB2, as important predisposition convened at MD Anderson Cancer Center, Houston, USA Invasive Breast Carcinoma (IBC) refers to a large and heterogeneous group of malignant genes that merit testing in all patients with suspicion December 9-11, 2018. 153 authors from 21 countries epithelial neoplasms of breast glandular elements. IBCs are classified by morphology of familial predisposition. Many other genes (two contributed. The end result is an authoritative reference book (below). All IBCs are grouped into biomarker-defined subtypes for treatment, based on examples are ATM, CHEK2) have been identified in that serves as the international standard for oncologists and estrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2). familial syndromes though there is limited data on pathologists. frequency and absent data on ethnic variations. Detailed familial syndromes with breast CA This exhibit is designed to increase radiologists’ and relevance are included: technologists’ understanding of breast pathology, ie to enhance Epithelial Tumours CME and CEU at this conference. Invasive breast carcinoma Invasive carcinoma of no special type BRCA 1/2-associated hereditary breast and ovarian Microinvasive carcinoma cancer syndrome Invasive lobular carcinoma Cowden syndrome Tubular carcinoma Ataxia-telangiectasia Cribriform carcinoma Li-Fraumeni syndrome, TP53-associated Invasive NST Invasive Lobular Mucinous carcinoma Li-Fraumeni syndrome, CHEK2-associated Mucinous cystadenocarcinoma CDH1-associated breast cancer Invasive micropapillary carcinoma PALB2-associated cancers Carcinoma with apocrine differentiation Peutz-Jeghers syndrome Metaplastic carcinomas Neurofibromatosis type 1 Rare and salivary gland-type tumours The polygenic component of breast cancer susceptibility Acinic cell carcinoma Metaplastic Tumours of the nipple Tubular Adenoid cystic carcinoma Secretory carcinoma Mucoepidermoid carcinoma Paget Disease Notes on core needle biopsy Polymorphous adenocarcinoma Nipple adenoma Tall cell carcinoma with reversed polarity Syringomatous tumor of the nipple (SyT) 5% of patients with screen-detected abnormalities Neuroendocrine neoplasms Paget Nipple adenoma typically undergo immediate excision, with 3:1 Ductal carcinoma in situ benign-to-malignant final diagnoses. Most patients Non-invasive lobular neoplasia with atypical breast lesions diagnosed on core biopsy Mucinous Papillary neoplasms are referred for surgical excision. However, recent Epithelial-myoepithelial tumours Metastastes to the breast studies indicate the rate of upgrade to carcinoma is lower than initially reported. Assure careful clinical- Adenomas DCIS Defined: malignant tumours originating from an extramammary organ or site pathologic and radpath correlation in: WHO Classification of Tumours Editorial Board. Breast tumours. Lyon, Tubular adenoma Mammography and ultrasound most commonly shows relatively small, irregular (France): International Agency for Research on Cancer, 2019. Lactating adenoma superficial masses, rarely spiculated. These require CNB for diagnosis, and Ductal adenoma comparison of mammary and extramammary malignant tissue is essential ADH: All patients should be referred for surgical Adenosis and benign sclerosing lesions Most common sources of breast metastases consultation and excision Benign epithelial proliferations ALH: Surveillance may be appropriate if incidental th In adults: lymphoma/leukemia, melanoma, pulmonary, ovarian, gastric, WHO 5 ed Broad Categories prostatic, renal cell, colorectal, mesothelioma, neuroendocrine, cervical CA. LCIS: Surveillance may be appropriate if incidental In children: rhabdomyosarcoma classic LCIS FEA: Surveillance may be appropriate for FEA if all calcifications removed Epithelial tumours Mesenchymal tumours Papilloma: Surveillance may be appropriate for Fibroepithelial tumours and hamartomas benign solitary and incidental papillomas Lipoma Tumours of the male breast Radial scar: Surveillance may be appropriate for Myofibroblastoma Tumours of the nipple incidental radial scars without atypia Vascular tumours: haemangioma, angiomatosis, atypical vascular lesions, Gynecomastia Mesenchymal tumours postradiation angiosarcoma, primary angiosarcoma Ductal carcinoma in situ Haematolymphoid tumours Fibroblastic and myofibroblastic tumours: nodular fasciitis, myofibroblastoma, Invasive carcinoma References desmoid fibromatosis, inflammatory myofibroblastic tumour Tumours of the male breast Gynecomastia Male breast CA • https://seer.cancer.gov/statfacts/html/breast.html Peripheral nerve sheath tumours: schwannoma, neurofibroma, granular cell tumour • WHO Classification of Tumours Editorial Board. Metastases to the breast Smooth muscle tumours: leiomyoma, lemoyosarcoma Acknowledgements Breast tumours. Lyon, (France): International Agency Adipocytic tumours: lipoma, angiolipoma, liposarcoma for Research on Cancer, 2019. Genetic tumour syndromes of the breast • Calhoun BC. Core needle biopsy of the breast: an Pseudoangiomatous stromal hyperplasia Joanna Schneider MD UNC SOM Class of 2019 Thomas J. Lawton MD UCLA Department of Pathology and Laboratory Medicine evaluation of contemporary data. Surg Pathol Clin GCT North Carolina Radiological Society 2018 Mar; 11(1):1-16. PMID 29413652.

2020

Mucinous Carcinoma PASH Fibroadenoma Phyllodes Invasive Lobular DCIS Medullary Pattern Invasive Micropapillary Papilloma with DCIS Invasive Carcinoma NST