First Report of Idiopathic Granulomatous Mastitis Treated with Methotrexate Monotherapy

To the Editor: Idiopathic granulomatous mastitis (IGM) is a rare, benign, but disfiguring inflammatory disease of the breast. It usually presents as a unilateral, expanding breast mass, occasionally with surrounding local inflammation1. Diagnosis is made by excisional biopsy: histology shows epithelioid and multinucleated giant cell granulomas limited to the mammary lobules with microabcesses2. Other causes of granulomatous lesions must be excluded, including infections with tuberculosis or fungi, and systemic diseases such as Wegener’s granulomatosus, sarcoidosis, and polyarteritis nodosa. The optimal treatment for IGM is unclear: most patients have been treated with wide surgical excision or total mastectomy, though recurrence is common1,3. High-dose glucocorticoids have been shown to be effective but not without complications, including difficult wound healing, fistula formation, and recurrence on withdrawal1,4,5. More recently, Kim and others have reported the use of methotrexate (MTX) in … Address reprint requests to Dr. G. Schmajuk, 1000 Welch Rd, Ste 203, Palo Alto, CA 94304. E-mail: schmajuk{at}stanford.edu