All cutaneous neural elements in clinically normal-looking skin from psoriatics are altered compared with those in skin from healthy persons, whose genetical makeup does not include a family history of psoriasis. Accelerated turnover of neural elements goes hand-in-hand with invasion of the epidermis by axons, Schwann cells, and perineurial cells. These are shed together with keratin.
In plaques this process is intensified, the majority of adventitial cells being distorted Schwann or perineurial cells. Fewer cells and axons penetrate the hyperplastic epidermis, but immigrant cells damage epidermal cells in their pathway.
Some of the dermal and epidermal cells in both clinically normal and plaque skin are strongly periodic acid-Schiff (PAS) positive.
Despite alterations of innervation, no changes in cutaneous sensibility were found in either clinically normal skin or plaques of psoriatics.
WEDDELL G, COWAN MA, PALMER E, RAMASWAMY S. Psoriatic Skin. Arch Dermatol. 1965;91(3):252–266. doi:10.1001/archderm.1965.01600090060012
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