Histochemical localization of hyaluronan in psoriasis, allergic contact dermatitis and normal skin.

In suction blister fluid from active psoriatic lesions we have previously found elevated concentrations of hyaluronan. The aim of this investigation was to study the localization of hyaluronan with a histochemical method, in biopsy specimens from lesions of 13 patients with progressive psoriasis. Ten normal subjects and seven patients with allergic contact dermatitis were also studied. In normal epidermis the highest intensity of hyaluronan staining was found in the intercellular spaces in the middle and upper spinous layer, whereas the staining was much weaker in the basal layer. No hyaluronan was detected in the granular layer or in the orthokeratotic stratum corneum. In the dermis there was pronounced staining of the papillary dermis and around the sebaceous glands, sweat glands, hair follicles and blood vessels. In six of the 16 specimens from psoriatic lesions the normal epidermal meshwork of hyaluronan was partly absent and replaced by diffuse staining of both the spinous and the basal layer. In the remaining ten of these 16 specimens the same type of meshwork was found in stratum spinosum as in normal skin. The parakeratotic stratum corneum contained hyaluronan, in contrast to the normal stratum corneum, where no hyaluronan was present. The pattern of hyaluronan staining in the dermis of the psoriatic lesions did not differ from that in normal dermis. In the majority of the allergic patch test reactions the junction was less distinct than in normal skin between dermis and epidermis and the normal hyaluronan pattern of the basal layer was abolished and replaced by a diffuse staining throughout the layer.(ABSTRACT TRUNCATED AT 250 WORDS)