Treatment of Granulomatous Mastitis: Is There a Role for Antibiotics?

Objective: To perform a retrospective review of the clinical characteristics, microbiological data, and clinical outcomes in patients with granulomatous mastitis (GM) who were treated at our institution with a unique strategy of prolonged antibiotic therapy as the primary treatment modality. Materials and Methods: A retrospective case series was performed on patients (n = 42) with GM seen at the breast specialty clinic of our institution between the years 2004 and 2014. Patients were primarily treated with lipophilic antibiotics, and steroids and surgery were reserved for refractory cases. Results: Bacteria were identified in 34 samples from 22/42 patients (52.3%). Diphtheroids (presumptive Corynebacterium spp.) were most commonly identified, followed by Corynebacterium spp. and Propionibacterium acnes (now Cutibacterium acnes). Antibiotics were our preferred first-line medical therapy and were used in 33/36 (91.7%) patients. The mean duration of antibiotic therapy was 7.0 +/- 4.5 months. Clarithromycin was our antibiotic of choice and was the initial antibiotic used in 15 of the 33 patients (45.5%) treated with antibiotics. Eleven patients required adjunctive therapy with prednisone. The mean duration of steroid therapy was 4.3 +/- 2.5 months. Surgery for therapeutic purposes included incision and drainage in seven patients, fine needle aspiration in eight patients, and excision of the fistulous tract in one patient. No patients had large-volume excisions. The average time from the first breast clinic visit to clinical resolution was 8.0 +/- 4.6 months. Conclusion: GM may be the result of a bacterial process that induces a unique form of inflammatory response. Clinicians should consider special requests to microbiology laboratories to attempt to isolate Corynebacterium spp. in the evaluation of samples sent to the laboratory for analysis. An extended course of a lipophilic antibiotic is a largely unexplored but potentially effective treatment option with low associated morbidity. More research is needed in this area.