Idiopathic granulomatous mastitis (IGM) is a benign chronic inflammatory condition of the breast of unknown etiology and without established treatment strategy.¹-⁶ IGM has been reported across races without a well-established predisposition to one specific ethnic group, but some studies report an association with those of Hispanic descent.¹,²,⁵,⁶ Additionally, there is no consensus on optimal treatment for IGM.¹-⁶ Treatment options range from observation, non-steroidal anti-inflammatory drugs (NSAIDS), antibiotics, and steroids to more invasive treatments, including surgical intervention.

This cross-sectional study which was approved by an institutional review board was performed on all patients with a diagnosis of IGM from 2018 to 2024 at Stony Brook University Hospital. Patients were identified based on either pathology-confirmed diagnosis or as a clinical diagnosis of exclusion. Patients were excluded if they had granulomatous mastitis secondary to systemic diseases (e.g. sarcoidosis), infection (e.g. tuberculosis), or foreign bodies. Clinical data was collected by chart review of these patients including age at diagnosis, sex, race, imaging (ultrasound and mammogram BIRADS score), and presentation. The management of IGM was categorized as observation, NSAIDs, antibiotics, steroids, incision and drainage, or excisional biopsy, as described by Bhattarai et al.⁷ Outcomes analyzed included non-recurrence, recurrence, indolence, or lost to follow up.

Twenty cases of IGM were identified by chart review. Of the patients diagnosed with IGM, 20% were diagnosed based on clinical features (n=4) and 80% of the diagnoses (n=16) were confirmed via pathology. Of the patients studied, 70% (n=14) were Hispanic, 25% (n=5) were white, and 5% (n=1) were Asian. These results are summarized in Table 1.

This study showed that most women with IGM at Stony Brook University Hospital were Hispanic. Another study further stratified by country of origin and found that most Hispanic women were specifically from Mexico, which was not seen in our work [7]. Of Hispanic women with IGM at Stony Brook University Hospital (n=14), 28.6% (n=4) were Ecuadorian, 21.4% (n=3) were unspecified, 14.3% (n=2) were Salvadorean, 14.3% (n=2) were Columbian, 7.1% (n=1) were Guatemalan, and 7.1% (n=1) were Honduran. This difference in country of origin may reflect demographic differences in regions of New York.

Hispanic women with IGM were significantly younger than their white counterparts and on average, followed up sooner, which may be ascribed to the observation that Hispanic women were more likely to present with a symptomatic lesion, thereby prompting closer follow-up by the patient or the surgeon to monitor for resolution of symptoms.

We found that most patients without recurrence had been treated with steroids, which contrasts with the findings of another study that found that antibiotic treatment with doxycycline as a first-line therapy resulted in complete resolution of IGM in 50% of patients that were studied.⁸

This descriptive cross-sectional study suggests that a racial predilection to IGM exists, specifically affecting mostly Hispanic women who tend to be younger at age of diagnosis than other racial groups. Additionally, we observed that outcomes differed by initial management of the disease; specifically, that most patients without recurrence of their disease had been treated with prednisone. Further studies are needed to discern the specific effect of therapeutic modality on resolution of IGM.