Microscopic analysis of lymphatic vessels in primary lymphedematous skin

Background: Although skin lymphatic system is implicated in primay lymphedema, the morphology and distribution of lymphatic vessels in the affected skin of the lower extremity of this disease are less described and understood. Our aim was to characterize the structural and distributional features of lymphatic vessels in the affected skin of the lower extremity of primary lymphedema patients and pinpoint their role in this disease. Methods: Skin biopsies of lower limb of 14 patients with primary lymphedema and 10 age-matched controls were performed for immunohistochemistry microscopic studies using podoplanin (a lymphatic marker) antibodies. All lymphatic vessels present in each section were counted and inner luminal diameter was measured by software. Results:The total density and inner luminal diameter of lymphatic vessels in the affected skin of the lower extremity of primary lymphedema patients were greater compared with controls (p=0.004, p=0.014, respectively). However, in the superficial 300 p m band of dermis, the density of lymphatic vessels in primary lymphedema was lower with respect to controls (p=0.00). In contrast, in deep dermis (>300 mu m), the density of lymphatic vessels in primary lymphedema was significantly higher compared with controls (p=0.00). Conclusion: The affected skin of the lower extremity of primary lymphedema patients is characterized by hyperplasia and dilation of lymphatic vasculature mainly located in deep dermis, which might have a pathogenic role in the evolution and in the clinical manifestations of the disease.