Idiopathic granulomatous lobular mastitis (IGLM) is a rare, chronic inflammatory breast disease first described in 1972.1 IGLM usually affects women during reproductive years and has similar clinical features to breast cancer.2 Ultrasonography and mammography yield nonspecific results and cannot adequately differentiate between malignancy and inflammation.3 Magnetic resonance imaging (MRI) is known to be more sensitive in detecting lesions in dense breasts; however, it does not differentiate between granulomatous lesions and other disorders.4,5 Histopathology is the gold standard for diagnosis.1-12
Infectious and autoimmune causes of granulomatous mastitis must be excluded before establishing an IGLM diagnosis. The clinical quandary that remains is how to adequately manage the disease. Although there are no defined treatment guidelines, current literature has proposed a multimodal strategy.6,9 In this report, we describe a case of IGLM successfully treated with surgical excision after failed medical therapy.
Case Presentation
A 43-year-old gravida 5, para 4 White woman presented with a 2-week history of right breast tenderness, heaviness, warmth, and redness that was refractory to cephalexin and dicloxacillin. She had no personal or family history of breast cancer; never had breast surgery and breastfed all 4 children.
An examination of the right breast demonstrated erythema and an 8-cm tender mass in the right lower outer quadrant but no skin retraction or dimpling (Figure 1). The mammography, concerning for inflammatory breast cancer, was category BI-RADS 4 and demonstrated a suspicious right axillary lymph node (Figure 2).
A core needle breast biopsy revealed granulomatous mastitis (Figure 3A), without evidence of malignancy. Rheumatology and endocrinology excluded secondary causes of granulomatous mastitis (ie, sarcoidosis, tuberculosis, granulomatosis with polyangiitis, and other autoimmune conditions). A pituitary MRI to assess an elevated serum prolactin level showed no evidence of microadenoma.
After a prolonged course of 8 months of unsuccessful therapy with prednisone and methotrexate, the patient was referred for surgical excision. Culture and special stains (Gram stain, periodic acid-Schiff stain, acid-fast Bacillus culture, Fite stain, and Brown and Benn stain) of the breast tissue were negative for organisms (Figure 3B). Seven months after excision the patient was doing well and had no evidence of recurrence.