Revisiting the role of lymphatics in Crohn's disease.

BACKGROUND: Early pathological observations consistently highlighted the involvement of the intestinal lymphatic system in Crohn's disease (CD), although this remains underappreciated in current conceptual models of disease pathogenesis. This narrative review synthesizes evidence supporting lymphatic dysfunction as a key contributor of CD pathogenesis, and discusses its therapeutic potential. METHODS: We searched PubMed to identify relevant studies on lymphatic biology in CD, including pathological, clinical, and experimental data. RESULTS: Lymphatic obstruction, lymphangitis, and lymphangiectasia are early, widespread features of CD; structural remodeling coexists with compensatory lymphangiogenesis, suggesting a bidirectional relationship in which lymphatic dysfunction both drives and is sustained by intestinal inflammation. Peyer's patches, closely integrated with the lymphatic network, may represent a portal of entry for luminal pathogens. CD susceptibility genes impair microbial handling at this interface, potentially enabling translocation into the lymphatics, endothelial injury, and the granulomatous lymphangitis hallmark of CD. Experimental models reinforce this framework: pathogens such as Yersinia or norovirus can induce lymphangitis preceding overt intestinal inflammation. Metastatic cutaneous CD, a rare extraintestinal manifestation involving lymphatic vessels characterized by granulomatous dermal inflammation at sites anatomically discontinuous from the gut, may provide a unique window into lymphatic pathology independent of the intestinal microbiome. CONCLUSIONS: These observations support an alternative view of CD in which intestinal lymphatic dysfunction plays an under-recognized role in both promoting and sustaining inflammation. This framework may explain disease features (patchy distribution, transmural inflammation, mesenteric hypertrophy) and positions the lymphatic system as a therapeutic target to restore drainage and modulate immune-lymphatic crosstalk.