Imaging features of metastases to the breast from extramammary non-hematological malignancies: a BI-RADS v2025 descriptive study

Purpose: The aim of this study was to evaluate the imaging features of metastases to the breast from extramammary non-hematological malignancies, by applying the updated descriptors and assessment categories of the ACR BI-RADS v2025 Manual.Materials and Methods: In this single-center descriptive study, 22 patients with histopathologically confirmed metastases to the breast from solid tumors were evaluated. Mammography (MG) was performed in 10 cases, ultrasound (US) in all cases, and magnetic resonance imaging (MRI) in one. Subsequently, all modalities were reviewed by two radiologists in consensus. Lesion morphology and BI-RADS category were reassessed according to the BI-RADS v2025.Results: The most common primary tumors were lung (n=7, 31.8%) and ovarian (n=5, 22.7%) carcinomas. Clinical presentation was predominantly unilateral (81.8%) and solitary (54.5%). Regarding MG findings, mass lesions (80%) and non-mass focal asymmetries (20%) were identified; furthermore, the most frequent mass morphology was a lobulated shape (n=4) with obscured margin (n=4). Notably, internal calcifications were absent in 100% of the cases. US evaluation revealed 21 masses and one non-mass lesion. Among mass lesions, the most common features were a lobulated shape (n=9), hypoechogenicity (n=15), and indistinct margin (n=10). Notably, an echogenic rind was identified in 63.6% of lesions, and posterior acoustic enhancement was present in 54.5%. Internal and/or peripheral vascularity was detected in 83.3% of lesions evaluated with Doppler US. Elastography showed hard (47.6%) and intermediate (52.4%) stiffness. The patient who underwent MRI had a circumscribed T2-hyperintense mass with thick rim-enhancement and diffusion restriction.Conclusion: According to the updated BI-RADS v2025 Manual, metastases to the breast from solid tumors frequently present as lobulated masses with indistinct or obscured margin. The absence of microcalcifications is a key feature favoring metastasis over primary breast carcinoma, except in rare psammomatous ovarian carcinoma. The high prevalence of an echogenic rind and the presence of non-mass focal asymmetries are critical diagnostic clues that should not be overlooked, particularly in dense breast parenchyma.