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Breast Imaging

E2461. Imaging and Clinical Management of Granulomatous Mastitis: What Every Radiologist Should Know

Brazeal H,  Seiler S,  Hayes J,  Dogan B,  Porembka J. University Of Texas Southwestern, Dallas, TX

Address correspondence to H. Brazeal (hilarybrazeal@gmail.com)

Background Information: Idiopathic granulomatous mastitis (IGM) is a rare inflammatory disease affecting predominantly parous women of reproductive age. Clinical presentation and imaging findings cannot be definitively distinguished from breast cancer. This presentation will illustrate typical clinical and imaging findings of IGM, describe the tissue sampling necessary to differentiate IGM from other processes, and explain the appropriate clinical management.

Educational Goals/Teaching Points: After reviewing this educational exhibit, you will be able to recognize the characteristic imaging appearance of IGM with mammography, ultrasound, and MRI and understand how to differentiate IGM from malignancy and other benign breast lesions in order to guide clinical management of IGM.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques: The cause of IGM is unknown, but it is likely related to an underlying autoimmune process. Both the clinical and imaging findings overlap with those of breast malignancy. Patients typically present with a breast mass, sometimes with associated pain or skin changes. IGM has a variable appearance on mammography, but most often appears as focal asymmetry, an ill-defined mass, or diffuse asymmetry. On ultrasound, IGM often appears as a hypoechoic mass or masses with or without tubular structures or as parenchymal heterogeneity. The MRI appearance of IGM is variable, including both nonmass enhancement and enhancing masses; these have variable enhancement kinetics and diffusion. Tissue sampling, ideally with core needle biopsy, is required for definitive diagnosis. On pathology, IGM is characterized by inflammatory changes and nonnecrotizing granulomas confined to breast lobules with no associated infection.

Conclusion: Clinical and imaging features of IGM overlap with breast malignancy. Diagnosis is made based on tissue sampling, ideally with core needle biopsy. If there are no contraindications, corticosteroids are the first line treatment. Wide local excision is a possible alternative if IGM does not respond to corticosteroid therapy.