Idiopathic Granulomatous Mastitis as a Benign Condition Mimicking Inflammatory Breast Cancer: Current Status, Knowledge Gaps and Rationale for the GRAMAREG Study (EUBREAST-15).

Simple Summary: Idiopathic granulomatous mastitis (IGM) is a rare breast disease that can be mistaken for inflammatory breast cancer. It requires a tissue biopsy for an accurate diagnosis. Even though it is not cancerous, IGM can cause emotional distress because of severe pain and ensuing breast deformity. It is important to distinguish IGM from other breast inflammations caused by infections. IGM is mostly found in premenopausal women, often after pregnancy or breastfeeding. Smoking and contraceptive use might be risk factors, but the evidence is unclear. The treatment options include NSAIDs, steroids, immunosuppressants, surgery, prolactin suppressants, and antibiotics; many patients relapse, making treatment challenging. This review summarizes current information, which mostly comes from case reports and small studies, and presents GRAMAREG as a registry for IGM initiated by the EUBREAST Study Group, which aims to collect detailed data on IGM to improve the knowledge base for diagnosis and treatment. Background: Idiopathic granulomatous mastitis (IGM) is a rare, benign inflammatory breast condition often mistaken for inflammatory breast cancer and, therefore, requires a biopsy for accurate diagnosis. Although not cancerous, IGM can cause emotional distress because of severe pain and ensuing breast deformity. Differentiating IGM from other breast inflammations caused by infections is essential. IGM mostly affects premenopausal women and is potentially associated with recent pregnancies and breastfeeding. The risk factors, including smoking and contraceptive use, have inconsistent associations. Steroid responses suggest an autoimmune component, though specific markers are lacking. Methods: We performed a narrative review on potential risk factors, diagnostics, and therapy of IGM. Results: Diagnostics and clinical management of IGM are challenging. The treatment options include NSAIDs, steroids, surgery, antibiotics, immunosuppressants, prolactin suppressants, and observation, each with varying effectiveness and side effects. Conclusions: Current IGM treatment evidence is limited, based on case reports and small series. There is no consensus on the optimal management strategy for this disease. The GRAMAREG study by the EUBREAST Study Group aims to collect comprehensive data on IGM to improve diagnostic and treatment guidelines. By enrolling patients with confirmed IGM, the study seeks to develop evidence-based recommendations, enhancing patient care and understanding of this condition. [ABSTRACT FROM AUTHOR]