The mineralization of elastic fibers and alterations of extracellular matrix in pseudoxanthoma elasticum. Ultrastructure, immunocytochemistry, and X-ray analysis.

Histologic paraffin sections of pseudoxanthoma elasticum (PXE)-involved skin of forearm and axilla were used for histochemistry and immunohistochemical and analytical electron microscopy to study the progressive mineralization in the dermis of patients with PXE. The von Kossa technique identified mineral deposits throughout the reticular PXE dermis. X-ray analysis revealed patterns of calcium and phosphorus deposition in the von Kossa-positive areas, and the immunohistochemical staining using monoclonal antibodies identified increased chondroitin-6-sulfate in these areas when compared with normal skin. Scanning transmission electron microscopy observation combined with X-ray dot mapping show calcium and phosphorus to be codistributed within the mineralized area. This study confirms by new methods the increase in chondroitin-6-sulfate, alterations in elastin and collagen, and a high calcium and phosphorus elemental distribution matching the mineralized area in the PXE dermis.