Clinical and Pathologic Features Associated With Invasive Breast Carcinoma With 2018 American Society of Clinical Oncology/College of American Pathologists In Situ Hybridization Group 2 Results (Human Epidermal Growth Factor Receptor 2 [HER2]/Chromosome 17 Centromere [CEP17] Ratio ≥2.0 and Average HER2 Copy Number <4.0).

Context.—: The American Society of Clinical Oncology/College of American Pathologists updated the human epidermal growth factor receptor 2 (HER2) breast carcinoma testing guideline in 2018 to address issues from uncommon HER2 fluorescence in situ hybridization (FISH) results. Based on the 2013 American Society of Clinical Oncology/College of American Pathologists guideline, cases wherein the HER2/chromosome 17 centromere (CEP17) ratio of 2.

Mammary Extranodal Rosai-Dorfman Disease With and Without Associated Axillary Lymphadenopathy: Insights for Practitioners of Breast Pathology.

Rosai-Dorfman disease is a rare proliferative histiocytic disorder of lymph nodes that is descriptively known as sinus histiocytosis with massive lymphadenopathy. Extranodal involvement of the parenchyma of the breast is uncommonly reported, with fewer than 50 cases of mammary extranodal disease detailed in the English-language literature. We characterize a retrospective series of adult female patients from a single institution with Rosai-Dorfman disease of the breast and axillary lymph nodes.

Mammary mesenchymal and fibroepithelial lesions: An illustrated cytomorphologic update with differential diagnoses.

The Uniform Approach to Breast Fine Needle Aspiration Biopsy was put forward by a learned group of breast physicians in 1997. This landmark manuscript focused predominantly on diagnosis and reporting of mammary epithelial lesions. Today, most American practitioners turn initially to core biopsy rather than aspiration biopsy for the first line diagnosis of solid breast lesions; however, recent efforts from the International Academy of Cytology have produced a system called the Standardized Reporting of Breast Fine Needle Aspiration Biopsy Cytology (colloquially labeled in 2017 as the "Yokohama System"), suggesting a new interest in breast fine needle aspiration (FNA), especially in resource limited settings or clinical practice settings with experienced breast cytopathologists.

Cystic neutrophilic granulomatous mastitis: The Cleveland Clinic experience with diagnosis and management.

Granulomatous mastitis is an uncommon inflammatory disease that typically presents with painful breast lesions. Recent publications have brought to light a specific subset of granulomatous mastitis patients with a distinct histological pattern of disease termed, "cystic neutrophilic granulomatous mastitis" (CNGM). Although many cases of granulomatous lobular mastitis have been thought to be idiopathic, this rare subset of an uncommon disease has been linked to infections with Corynebacterium species.