In psoriasis the epidermis, including the subepidermal vascular plexus, grows downwards into the dermis

Abstract

In psoriatic lesions, capillaries in the papillary bodies seem elongated and increased in number. Most researchers postulate that there is angiogenesis of intrapapillary capillaries in psoriatic plaques. In this study we will show, by means of computer-aided three-dimensional reconstructions in four patients suffering from chronic plaque-type psoriasis, and in a healthy volunteer, that the elongation and increase of intrapapillary capillaries are not the result of angiogenesis. Our three-dimensional reconstructions show that the papillary body of psoriasis contains lymph capillaries besides the blood capillaries. Additionally, an inclusion of two tips of papillary bodies into one papilla at the base of the rete ridges becomes obvious. The vessels of the two tips are connected by a horizontal vessel. At the level of the horizontal connecting vessel there is the blind beginning of a lymphatic vessel. The connecting blood vessel, as well as the lymph capillary, belong to the horizontal subpapillary venous plexus but lie within the papillary body. The three-dimensional reconstructions show that by growing towards the dermis, the rete ridges include the vessels of the horizontal plexus. Surrounded by rete ridges, these vessels appear as intrapapillary capillaries.