Lymphatic and blood vessels in scleroderma skin, a morphometric analysis

Summary 

Vascular involvement is frequent in systemic sclerosis, but the role of the lymphatic vasculature is poorly known. Our aim was to evaluate lymphatic vessels in systemic sclerosis skin lesions. We studied skin forearm biopsies of 9 patients with systemic sclerosis and 7 age-matched controls. Lymphatic vessels were labeled with the monoclonal antibody D2-40 and blood vessels with a polyclonal antibody to von Willebrand Factor. All blood and lymphatic vessels present in each section were counted and total area, inner luminal area, and shape factors were measured. The number of blood and lymphatic vessels in papillary dermis was greater and their diameter lower than in reticular dermis both in systemic sclerosis and controls. In the reticular dermis, the number of lymphatic vessels was markedly reduced in systemic sclerosis (4.9 ± 1.1 μm⁻² versus 8.9 ± 1.2 μm⁻² P = .03), and a similar trend was observed in papillary dermis (8.4 ± 3.7 μm⁻² versus 8.1 ± 5.3 μm⁻²). Interestingly, the number of periglandular lymphatics in systemic sclerosis was not different from controls. The inner luminal area (possibly indicating compensatory dilation) of lymphatic vessels, particularly the periglandular ones, was greater in systemic sclerosis than in controls. No differences were observed in the number of blood vessels, but the percentage of blood vessel profiles (without lumen) was significantly less in systemic sclerosis both in papillary and in reticular dermis. In conclusion, our data show that skin lesions in systemic sclerosis are characterized by a selective rarefaction of lymphatic vasculature that spares periglandular vessels and that might have a pathogenic role in the evolution and in the clinical manifestations of the disease.

Abbreviations: SSc, systemic sclerosis, vWF, von Willebrand Factor, VEGF, Vascular Endothelial Growth Factor

Keywords: Systemic sclerosis, Lymphatic vessels, Blood vessels, Skin, Immunohistochemistry