Abstract
BACKGROUND: Lymphedema is common after lymphatic damage in cancer treatment, with negative impacts on function and quality of life. Evidence suggests that blood vessel microvasculature is sensitive to irradiation and trauma; however, despite knowledge regarding dedicated mural blood supply to arteries and veins (vasa vasorum), equivalent blood vessels supplying lymphatics have not been characterized. We studied collecting lymphatics for dedicated mural blood vessels in our series of 500 lymphaticovenous anastomosis procedures for lymphedema, and equivalent controls. METHODS: Microscopic images of lymphatics from lymphedema and control patients were analyzed for lymphatic wall vascular density. Collecting lymphatics from 20 patients with lymphedema and 10 control patients were sampled for more detailed analysis (podoplanin immunostaining, light/confocal microscopy, microcomputed tomography, and transmission electron microscopy) to assess lymphatic wall ultrastructure and blood supply. RESULTS: Analysis revealed elaborate, dense blood microvessel networks associating with lymphatic walls in lymphedema patients and smaller equivalent vessels in controls. These vasa vasora or "arteria lymphatica" were supplied by regular axial blood vessels, parallel to lymphatic microperforators linking dermal and collecting lymphatics. Lymphatic walls were thicker in lymphedema patients than controls, with immunohistochemistry, computed tomography, transmission electron microscopy, and confocal microscopy characterizing abnormal blood vessels (altered appearance, thickened walls, elastin loss, narrow lumina, and fewer red blood cells) on these lymphatic walls. CONCLUSIONS: Dedicated blood vessels on lymphatics are significantly altered in lymphedema. A better understanding of the role of these vessels may reveal mechanistic clues into lymphedema pathophysiology and technical aspects of lymphedema microsurgery, and suggest potential novel therapeutic targets.