Akshay Ravandur;
Boston Medical Center; Boston University Chobanian & Avedisian School of Medicine
Jordana Phillips;
Boston Medical Center; Boston University Chobanian & Avedisian School of Medicine
Anna Kobzeva-Herzog;
Boston Medical Center; Boston University Chobanian & Avedisian School of Medicine
Andrea Merrill;
Boston Medical Center; Boston University Chobanian & Avedisian School of Medicine
Priscilla Slanetz;
Boston Medical Center; Boston University Chobanian & Avedisian School of Medicine
Background
Granulomatous mastitis (GM) is a rare, benign, inflammatory breast condition that most commonly occurs in postpartum women within 6 years of pregnancy and is most often treated noninvasively with steroids, antibiotics, and immunosuppression. Due to nonspecific clinical and imaging findings, GM is often misdiagnosed as infectious mastitis, inflammatory breast cancer, or other granulomatous disease. GM is typically imaged with a combination of ultrasonography, mammography, and MRI, but core biopsy is essential for definitive diagnosis.
Educational Goals / Teaching Points
Risk factors for GM include younger age and multiparity. Symptoms include palpable mass(es), pain, erythema, abscesses, draining fistulas, and axillary lymphadenopathy. Patients may have GM unilaterally or bilaterally. The differential diagnosis includes inflammatory breast cancer, infectious mastitis, and systemic diseases such as tuberculosis, sarcoidosis, fungal infection, or foreign body.
Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
On mammography, GM can present as focal asymmetry with one or more masses. Calcifications are not typically seen, and nipple retraction has been observed. Notably, mammography may be negative in patients with GM. Ultrasonography can show solitary or multiple circumscribed to irregular masses. Complex cystic masses, consistent with an abscess, may be present. Lesions are typically hypoechoic or have heterogeneous echotexture with a sinus tract to the skin surface. There may be edema of surrounding soft tissues, and skin thickening can appear with longstanding GM. On MRI, GM presents as a heterogeneously enhancing solitary or multiple T1 hypointense masses, often with areas of T2 hyperintensity and variable kinetics including washout.
Conclusion
In a younger, postpartum patient with new mass(es), inflammation, and nonspecific imaging findings, consider GM as part of the differential alongside inflammatory breast cancer. Core biopsy is essential for definitive diagnosis.
