Background: Lipoid proteinosis is a rare autosomal recessive disorder characterized by deposition of hyaline-like material in several organs, including skin. Pathogenic mutations have been found in the extracellular matrix protein 1 gene (ECM1). Recent studies have disclosed that ECM1 is also a target antigen for autoantibodies in patients with the acquired disease, lichen sclerosus. Both conditions have been reported to show abnormalities in dermal blood vessels but these changes have not been fully assessed.
Objective: The purpose of this study was to investigate the architecture of the cutaneous microvasculature in lipoid proteinosis and lichen sclerosus to better determine the role of ECM1 in the skin pathology observed in these disorders.
Methods: Labeling of skin biopsies (lipoid proteinosis, lichen sclerosus and control skin) with antibodies to type IV collagen and laminin-1 and reconstruction of the dermal blood vessels using laser confocal microscopy and computer imaging.
Results: In both lipoid proteinosis and lichen sclerosus there was reduplication of the basement membranes surrounding blood vessel walls. There were enlarged vessels in the mid and deep dermis that were orientated parallel to the dermal-epidermal junction. In addition, the normal capillary loop network in the dermal papillae, as well as the subcutaneous plexus and transverse connecting vessels were lacking in both disorders.
Conclusion: This study demonstrates that skin microvasculature is grossly altered when ECM1 is targeted by inherited mutations (lipoid proteinosis) or acquired autoantibodies (lichen sclerosus) and that this glycoprotein appears to have an important role in regulating blood vessel physiology and anatomy in the skin.