Histologic Correlation of Breast Biopsies Presenting as Non-Mass Enhancing Lesions on Magnetic Resonance Imaging: A Contemporary Single Institutional Series

Abstract

Abstract Introduction/Objective Non-mass enhancement (NME) in breast tissue is an area of enhancement on MRI that appears distinct from background breast parenchyma, but lacks definitive features of a mass. NME is characterized by its internal enhancement pattern and distribution, and can represent benign, high risk, or malignant pathology. Given this considerable overlap, a core biopsy is often necessary for diagnosis and management. We aimed to elucidate the most frequent histologic findings found on breast biopsies for MRI NME. Methods Using our institutional database we identified 70 female patients with high risk status for breast cancer with MRI screen detected NME (BIRADS-4-suspicious for malignancy) that underwent subsequent biopsy procedure during the period of 01/2016-12/2017. Primary pathologic diagnoses were subcategorized as follows: malignant, atypical, benign mass-like lesions, fibrocystic changes (proliferative, nonproliferative), or “other” primary diagnoses. Results The median age of patients was 48 years (range: 22-76 years). Of the 70 patients, 66 underwent MRI-guided core biopsy, 3 underwent ultrasound-guided core biopsy and 1 underwent excisional biopsy. The primary diagnosis was analyzed. Of these 70 cases, 8 (11.4%) were malignant (7 with ductal carcinoma in situ and 1 with invasive ductal carcinoma), 1 (1.4%) had atypical lobular hyperplasia, and the remaining 61 (87.1%) showed benign findings (36 with fibrocystic changes (FCC), 22 benign mass-like lesions, 3 with other non-specific findings). The FCC were subcategorized as proliferative (usual ductal hyperplasia, columnar cell change, incidental radial scar, incidental intraductal papilloma, sclerosing adenosis, focal pseudoangiomatous stromal hyperplasia (PASH)) or nonprolifeative (stromal fibrosis, duct ectasia, apocrine metaplasia). Majority (61.1%) of FCC were both proliferative and nonproliferative, 22.2% proliferative only and 16.7% nonproliferative only. Benign mass-like lesions included PASH (45.4%), fibroadenomatoid nodule (22.7%), fat necrosis (18.2 %) and remaining had the diagnosis of clustered apocrine cysts, papillomatosis, and radial sclerosing lesion. Conclusion Less than a third of cases showed malignant findings and more than two-third of cases showed benign findings with a high rate of detection of proliferative lesions and PASH.