Idiopathic Granulomatous Lobular Mastitis: A Mimicker of Inflammatory Breast Cancer

Background: Idiopathic granulomatous lobular mastitis (IGLM) is a rare, chronic inflammatory breast disease without a known etiology. Even though the current literature proposes several treatment strategies, there is no universal consensus for long-term management. Case Presentation: A 43-year-old White woman (gravida 5, para 4) presented with a 2-week history of right lower outer quadrant breast tenderness, heaviness, warmth, and redness. Mammography and ultrasound were concerning for inflammatory breast cancer. Biopsies returned as granulomatous mastitis without malignancy. After 8 months of unsuccessful therapy with prednisone and methotrexate, surgeons excised the breast tissue. Cultures and special stains were negative for other organisms. At the 7-month follow-up, no evidence of recurrence was seen. Conclusions: As there remains no consensus behind the etiology or management of IGLM, our case demonstrates a reasonable and successful stepwise treatment beginning with medical therapy before proceeding to surgical cure. Because of possible malignancy risk with chronic IGLM, patients should not delay surgical excision if their condition remains refractory to medical therapy alone.