Associations of obesity-related mammary intraductal secretions with inflammatory severity, immune dysregulation, and adverse prognosis in non-puerperal mastitis: a retrospective cohort study.

PURPOSE: This study aimed to evaluate the association between mammary intraductal secretions (IDS) and demographic characteristics, clinical manifestations, laboratory indicators and prognosis in patients with non-puerperal mastitis (NPM). PATIENTS AND METHODS: A retrospective analysis of 340 NPM patients who underwent surgical treatment at the Department of Breast, Shuguang Hospital, between April 2020 and December 2021 was conducted. Based on intraoperative findings of IDS, patients were divided into two groups: the IDS group (with intraductal lipid-like secretions) and the non-IDS group (without intraductal lipid-like secretions). Demographic data, clinical features, laboratory parameters, and prognostic outcomes were systematically compared between the two groups. RESULTS: Patients with NPM and IDS had a significantly higher median age at disease onset (33 years vs. 32 years; P = 0.047) and body mass index (BMI) (24.0 kg/m2 vs. 22.9 kg/m2; P = 0.013) compared with those in the non-IDS group. Multivariable logistic regression analysis identified older age and overweight/obesity (BMI ≥ 24 kg/m2) as independent risk factors for IDS in NPM. Although clinical symptoms did not differ significantly between the two groups, the IDS group demonstrated elevated systemic inflammatory markers, including C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and fibrinogen (Fg) (all P < 0.05). Immunological assessment revealed significantly higher levels of complement component 3 (C3), complement component 4 (C4), and total immunoglobulin E (IgE) in humoral immunity, as well as an increased proportion of regulatory T cells (Treg) in cellular immunity (all P < 0.05). No significant differences were observed between groups in prolactin (PRL) levels, lipid profiles, or cytokine concentrations (all P > 0.05). During follow-up, patients in the IDS group experienced longer healing times, higher rates of ipsilateral recurrence, and a greater incidence of bilateral disease compared with those in the non-IDS group (all P < 0.05). CONCLUSIONS: This study demonstrates that obesity-related IDS are significantly associated with increased systemic inflammation, immune dysregulation, and unfavorable prognostic outcomes in NPM. The identification of IDS provides valuable insight for risk stratification and supports the development of personalized management strategies. Overweight and obesity were identified as independent risk factors for IDS, highlighting weight control as a potential therapeutic approach. Future investigations should focus on elucidating the underlying mechanisms and exploring targeted therapeutic strategies to improve clinical outcomes.