Clinicopathological Features, Surgical Outcomes and Microbial Patterns in Chronic Granulomatous Mastitis: A Retrospective Study from a Public Hospital in Lima, Peru

Objective: To evaluate the clinicopathological characteristics of patients, surgery-related factors, and microbial patterns in patients diagnosed with chronic granulomatous mastitis (GM) treated at a public hospital in Lima, Peru. Methods: Retrospective study that included 161 women diagnosed with chronic GM at the Hospital de Emergencias Grau, Seguro Social de Salud, Lima, Peru, between 2019 and 2021. The diagnosis of GM was established based on anatomical and microbiological criteria. We evaluated clinicopathological features, and factors associated with the need for oncoplastic surgery and postsurgical complications. Additionally, we analyzed 26 out of 161 breast tissue samples to detect the presence of pathogens using next-generation sequencing (NGS). Results: The average age was 37.7 ± 8.4 years, 53.9% reported the use of hormonal contraceptives, and 14.8% displayed elevated prolactin. Eighty percent of patients received corticosteroids, and 50.9% underwent surgical intervention, with 22.5% experiencing postsurgical complications. Factors associated with the need for surgery included the presence of a tumor, inflammation, shorter disease duration, higher Breast Imaging-Reporting and Data System classification, lesion size of 2–5 cm, and corticosteroid use. A recurrence rate of 3.8% was identified. Among the 26 analyzed samples, Corynebacterium was detected in 80.8%, with Corynebacterium kroppenstedtii identified in 13 of the 26 (50%) samples. Conclusion: Medical treatment was the initial choice for all patients, nearly half underwent oncoplastic surgery, with some postsurgical complications reported. Nonetheless, chronic GM recurrence was low. Corynebacterium was the most frequently identified genus through NGS.