Idiopathic Granulomatous Mastitis: A Comprehensive Review of Etiology, Diagnosis, and Management

Idiopathic granulomatous mastitis (IGM) is a rare, benign, and chronic inflammatory breast disease of uncertain etiology. It often mimics infectious mastitis and inflammatory breast cancer in both clinical and radiologic presentations, leading to diagnostic and therapeutic challenges. This review aims to provide a comprehensive summary of the current literature regarding the etiology, pathogenesis, clinical manifestations, diagnostic strategies, and treatment options for IGM. A narrative review was conducted using an extensive search of the PubMed database, focusing on articles that discuss various aspects of IGM, including its potential autoimmune, hormonal, and infectious origins, as well as current diagnostic and management approaches. IGM most commonly affects women of reproductive age, often within a few years postpartum. Histologically, it is characterized by non-caseating granulomatous inflammation centered on breast lobules. Although corticosteroids are widely used as the first-line therapy, treatment regimens vary significantly across centers, and relapse is not uncommon. Immunosuppressive agents, such as methotrexate, have shown promising results in steroid-resistant cases. Surgical interventions are generally reserved for refractory cases because of the risk of recurrence and unfavourable cosmetic outcomes. The role of infectious agents, particularly Corynebacterium kroppenstedtii, remains controversial, and distinguishing between idiopathic and infectious GM is crucial for management. IGM is a multifactorial and clinically heterogeneous condition requiring individualized, multidisciplinary management. There remains a need for further prospective studies and consensus guidelines to optimize diagnosis and treatment, especially in recurrent or refractory cases.