ABSTRACT

Mastitis is a benign inflammatory disease of the breast and usually occurs in the 2^nd-4^th decade in women of reproductive age. The most common types encountered in clinical practice are lactational mastitis and idiopathic granulomatous mastitis (IGM). Autoimmune mastitis, periductal mastitis, radiation-associated mastitis, silicone implant-associated mastitis, xanthogranulomatous mastitis and eosinophilic mastitis, which are included in the definition of non-IGM non-infectious mastitis, are rare inflammatory conditions. Autoimmune mastitis is a group of heterogeneous diseases with different pathophysiological processes that occur when systemic autoimmune diseases rarely affect the breast secondarily. The main types of autoimmune mastitis are diabetic mastitis associated with organ-specific autoimmunity; connective tissue diseases such as systemic lupus erythematosus, Schögren’s-associated mastitis; vasculitic diseases such as eosinophilic granulomatosis, granulomatosis with polyangiitis-associated mastitis; secondary breast involvement in systemic granulomatous diseases such as sarcoidosis and Crohn’s disease, and immunoglobulin G4-related breast involvement that forms pseudotumoral masses in many different anatomical locations in the body. In particular, autoimmune mastitis, although the pathophysiological processes are different, basically results in lymphocytic infiltration; diagnosis is made by tissue biopsy in Breast Imaging Reporting and Data Systems 4 and 5 categories with imaging findings such as hypoechoic mass with irregular borders on ultrasound, asymmetric irregular/spiculated opacities on mammography, heterogeneous mass or nonmass on MRI and sometimes causing wash-out on dynamic examination.