Histochemistry of the dermal ground substance of initial psoriatic lesions.

30 cases of initial psoriasis were studied. Pinhead-sized lesions, recently appeared, were excised and studied with histochemical methods for acid mucopolysaccharides. In all specimens a well defined reduction of the material stained with colloidal iron, with alcian blue with critical electrolyte concentrations and with toluidine blue was observed in the upper dermis, in particular in the papillary dermis in the center of the lesions, in correspondence of the squirting papillae. The more evident reduction of the staining with alcian blue with 0.1 M and 0.2 M MgCl2 suggests that the changes of the dermal ground substance are predominantly due to an alteration of the hyaluronic acid.