Comparative study between contrast enhanced mammography and breast MRI in local pre-operative staging of invasive lobular carcinoma: A cross-sectional study.

BACKGROUND: Invasive lobular carcinoma (ILC) is the second most common subtype of breast cancer and is often difficult to detect and accurately stage because of its infiltrative growth pattern, multifocality, multicentricity, and potential bilaterality. Accurate preoperative assessment of disease extent is essential for optimal surgical planning. Breast magnetic resonance imaging (MRI) is considered the reference imaging modality for staging breast cancer, while contrast-enhanced mammography (CEM) has emerged as a promising alternative with improved accessibility and lower cost. OBJECTIVE: To compare the performance of contrast-enhanced mammography and breast MRI in the local preoperative staging of invasive lobular carcinoma and to evaluate their agreement with histopathological findings regarding lesion size, lesion number, multifocal-multicentric disease, and laterality. METHODS: This cross-sectional study was conducted over 18 months and included 39 female patients with histopathologically confirmed invasive lobular carcinoma. Twenty-four patients underwent CEM and 27 underwent breast MRI, with 12 patients undergoing both examinations. Imaging findings were compared with postoperative histopathological results, which served as the reference standard. Agreement regarding lesion number, size of the largest lesion, multifocal-multicentric disease, and laterality was assessed using appropriate statistical analyses. RESULTS: MRI demonstrated excellent agreement with pathology for lesion size classification (96.3%, κ=0.924), with high sensitivity (93.75%) and specificity (100%). In contrast, CEM significantly overestimated lesion size and showed moderate agreement (66.67%, κ=0.356), despite high sensitivity (90.91%). Both modalities showed strong performance in detecting multifocal-multicentric disease, with MRI demonstrating higher sensitivity (94.74%) and CEM higher specificity (100%). For laterality assessment, MRI achieved perfect agreement with pathology (100%), while CEM demonstrated excellent agreement (95.83%). Overall, MRI showed the closest concordance with pathological findings. CONCLUSIONS: Both CEM and MRI are effective imaging modalities for preoperative staging of invasive lobular carcinoma. MRI provides superior accuracy in assessing tumor size and disease extent and remains the preferred staging modality. However, CEM offers excellent performance in evaluating multifocality, multicentricity, and laterality, making it a valuable alternative when MRI is unavailable or contraindicated.