Idiopathic granulomatous mastitis a mimicking disease: a case report.

Background: Idiopathic granulomatous mastitis (IGM) is a rare, benign, chronic inflammatory breast disease that frequently mimics infection or malignancy, resulting in diagnostic and therapeutic challenges. Although erythema nodosum is a recognized extramammary manifestation, it occurs in approximately 10% of cases and may further obscure timely diagnosis. Our objective is to present a rare case of granulomatous mastitis and highlight the challenges associated with its diagnosis and management. Case Description: We report the case of a 25-year-old Hispanic female who presented with persistent right breast inflammation unresponsive to multiple courses of antibiotic therapy. Diagnostic evaluation with core needle biopsy confirmed IGM. The patient developed concurrent erythema nodosum, representing a rare clinical presentation. Initial management with high-dose systemic corticosteroids resulted in significant adverse effects and progressive disease. Given refractory symptoms and intolerance to medical therapy, the patient underwent a right total mastectomy. Final surgical pathology confirmed the diagnosis of IGM. Conclusions: This case underscores a rare association between IGM and erythema nodosum and highlights the importance of early tissue diagnosis to guide management. While systemic corticosteroids and immunosuppressive therapy remain the cornerstone of treatment, surgical intervention should be considered in patients with severe, refractory disease or those experiencing significant complications from medical therapy. An individualized, severity-based approach and multidisciplinary management are essential for optimizing outcomes in this uncommon condition.