Clinical features and therapeutic management of idiopathic granulomatous mastitis

Idiopathic granulomatous mastitis is a rare inflammatory breast disease affecting women aged 20-40 years, which can mimic infectious or neoplastic mastitis. This retrospective study at Saint-Louis Hospital, Paris, France, from 2010 to 2023, analysed histologically confirmed disease in 19 patients to refine its clinical and pathological features and evaluate treatments. Clinically, 89% of patients presented with one or more erythematous breast masses, often associated with abscesses, adenopathy, nipple retraction, oedema or fistulas. Histology showed large perilobular granulomas with polymorphic inflammation. Among the 18 treated patients, nonsteroidal anti-inflammatory drugs (NSAIDs) achieved complete remission in 50% (6/12), corticosteroids in 40% (2/5) and surveillance alone in 60% (5/8) of minimally symptomatic patients. Antibiotics led to partial remission in 23% but not complete remission. Surgery was not recommended because of its aesthetic impact. The median time to complete remission was 6 months, with three relapses. NSAIDs appeared to be an effective first-line treatment, while antibiotics showed limited efficacy. Further research is needed to standardize therapeutic protocols.