Lipedema as a Syndrome of Adipose Mast Cell Activation and Type 2 Immune Orchestration: A Testable Neuroimmune Framework

Lipedema affects an estimated 11–12% of women worldwide and is characterized by bilateral, symmetric adipose deposition in the lower extremities, disproportionate pressure pain, spontaneous bruising, and resistance to conventional dietary interventions. Despite its prevalence, lipedema lacks a unifying mechanistic framework. Current descriptions treat it as a fat storage disorder with secondary vascular and inflammatory features, leaving critical observations mechanistically unexplained: a highly characteristic quantitative sensory testing (QST) pattern with no published alternative mechanistic explanation, a paradoxical immunological profile, a 35–40% comorbidity with fibromyalgia, a 1.42 relative risk for ADHD, estrogen-dependent onset, and asymmetric expression in the presence of local vascular triggers.We propose the gfWAT-IIT2 framework, which posits that lipedema is fundamentally a syndrome of polarization of the gluteofemoral white adipose tissue (gfWAT) microenvironment toward innate type 2 immunity (IIT2), amplified by estrogen via mast cell estrogen receptors, and generating neuropathic pain through selective histaminergic sensitization of Aδ/C fibers (H1/H4 receptors, PPT↓) and inhibition of Aβ fibers (H3 receptor, VDT↑), with thermal thresholds remaining normal: a triad that is mechanistically explained by histaminergic peripheral sensitization.The gfWAT-IIT2 framework integrates reported clinical, sensory, immunological, and depot-specific observations into a testable mechanistic cascade, generates fourteen falsifiable predictions, and repositions the therapeutic target from adipocyte to mast cell. The framework further proposes that asymmetric lipedema (where one limb expresses the disease more severely due to an identifiable local trigger) constitutes a natural controlled experiment suggesting that local trigger removal may be disease-modifying in selected patients with documented triggers.