Electron Microscopic Studies of the Microcirculation in Psoriasis

Abstract

The microcirculation in the lesions of pustular psoriasis of von Zumbusch and psoriasis vulgaris were studied by light and electron microscopy. A consistent finding in the dermal papillae and upper third of the dermis was the presence of thin walled vessels. They had endothelial cell junctional gaps a poorly developed basal lamina, an absence of pericytes, and they contained red blood cells. The uninvolved skin of these patients showed identical findings, but less often. Less frequently, endothelial cell gaps were also seen in the post-capillary venules in the dermal papillse of psoriatic lesions. None of the control specimens showed these vascular findings in these locations. The presence of endothelial cell gaps implicates a role of the chemical mediators of inflammation in psoriasis. The thin walled vessels could either represent the arterial capillary segment of the microcirculation which is abnormally permeable because of the gaps or else lymphatic capillaries which are clearing the interstitial space of blood cells and serum. The abnormally permeable vessels in this instance could be the post-capillary venules. The nature of the thin walled vessels is currently under study.