Pathological mechanisms and clinical significance of the association between metabolic syndrome and granulomatous mastitis based on intermingled phlegm-blood stasis theory

To examine the relationship between metabolic syndrome (MS) and its key components in granulomatous mastitis (GM), we explored potential pathological mechanisms through the lens of traditional Chinese medicine (TCM), particularly the concept of intermingled phlegm-blood stasis. In this retrospective study, we enrolled 172 patients with GM and 164 patients with non-inflammatory benign breast masses. Metabolic indicators (waist circumference [WC], blood lipids, etc.), inflammatory markers (C-reactive protein, interleukin-6, tumor necrosis factor-α), and adipose tissue CD68 expression were measured. Logistic regression was used to analyze risk factors and receiver operating characteristic curves were used to evaluate diagnostic efficacy. The correlation between TCM pathogenesis and biomarkers was also examined. MS prevalence was significantly higher in the GM group than in the controls (26.16% vs. 6.10%, P < .001). Multivariate analysis identified abdominal obesity (WC ≥ 80 cm, odds ratio [OR] = 1.065) and low levels of high-density lipoprotein cholesterol (HDL-C; <1.29 mmol/L, OR = 0.066) as independent risk factors for GM ( P < .001 for both). Among patients with GM, HDL-C levels were inversely correlated with inflammatory markers (r = −0.341 to −0.440), whereas patients with concurrent MS demonstrated greater CD68 macrophage infiltration ( P < .001). According to TCM, abdominal obesity corresponds to “spleen deficiency with phlegm-dampness accumulation,” and low HDL-C reflects “deficiency of vital qi,” which collectively lead to phlegm-blood stasis obstruction in the mammary collaterals; this aligns with the key MS driving mechanisms of chronic inflammation and immune dysregulation. MS promotes GM development through chronic inflammation and immune dysregulation, with abdominal obesity and low HDL-C levels serving as core risk factors. The TCM theory of intermingled phlegm-blood stasis provides a novel interpretation of the metabolic-inflammatory mechanisms underlying GM. Accordingly, we propose phlegm-resolving and blood-activating strategies as potential therapeutic approaches for metabolic–immune axis regulation.