Metaplastic Breast Carcinoma: Radiologic-Pathologic Correlation.

Area of Science:

• Oncology
• Radiology
• Pathology

Background:

• Metaplastic breast carcinoma (MBC) is a rare, aggressive malignancy characterized by epithelial differentiation into mesenchymal and/or squamous components.
• It is typically a triple-receptor negative invasive breast cancer (TNBC) with nonspecific imaging findings.
• MBC often presents as a larger mass in postmenopausal women, with a higher incidence of distant metastases but less frequent axillary nodal involvement.

Purpose of the Study:

• To review the pathological definition, clinical presentation, and imaging characteristics of metaplastic breast carcinoma.
• To highlight the differential diagnosis of MBC, emphasizing its potential to mimic benign breast lesions.
• To underscore the importance of considering MBC in the differential diagnosis, particularly with specific clinical findings.

Main Methods:

• Review of pathological features defining MBC.
• Analysis of characteristic imaging findings across mammography, ultrasound (US), and magnetic resonance imaging (MRI).
• Discussion of clinical presentation and comparison with non-MBC breast cancers.

Main Results:

• Mammography typically shows circumscribed masses; spiculated features are less common than in non-MBC.
• Ultrasound often reveals solid masses with cystic spaces (necrosis).
• MRI may show T2 hyperintense masses with rim enhancement; findings can mimic benign tumors.

Conclusions:

• Radiologists should include MBC in the differential diagnosis for breast masses with nonspecific imaging features, especially in postmenopausal women with palpable findings.
• Accurate pathologic diagnosis on core biopsy can be challenging due to MBC's heterogeneity.
• Metaplastic breast carcinoma is associated with a worse long-term prognosis compared to other invasive breast cancers, including other TNBCs.