The pseudo-elongation of capillaries in psoriatic plaques

The intrapapillary vessels in the psoriatic plaque are described as elongated, twisted and multiplied. However there is neither proliferation nor necrosis of vessels in growing and dissolving psoriatic plaques. In 120 patients suffering from psoriasis vulgaris, computer-supported image analysis and in 8 patients additionally 3D reconstructions were made to investigate the regression process of the intrapapillary capillaries in the active and resolving psoriatic plaque. In acanthotic epidermis with a thickness of > 400 microns the first subpapillary horizontally oriented plexus is included in the papilla due to the down-growing of the epidermal rete pegs. In the evaluation of the computer-supported image analysis there is only little variation in the levels of the different vascular plexuses within the dermis, while the epidermis is decreasing from > 600 microns to > 100 microns. In the 3D reconstruction of the transition of a psoriatic lesion into adjacent non-involved skin it could be proved that, apart from the epidermal alterations, there is virtually no difference in the arrangement of the vessels between the psoriatic lesion and the adjacent non-involved skin. In psoriasis the vessels do not proliferate, they rest as resident structures and are embraced by the down-growing rete pegs.