The significance of histologic analysis of skin lesions in porphyria cutanea tarda. Light microscopy, electron microscopy, immunohistochemical and immunofluorescence analysis.

Porphyria cutanea tarda (PCT) is one of several entities in the differential diagnosis of scleroderma. We report a 62-year-old man with PCT diagnosed since two decades. Clinical data and the results of light microscopy, immunohistochemistry, immunofluorescence and electron microscopy of skin biopsies are presented. The biopsy revealed sclerosis of the dermis mainly due to increased collagens I and III, and accumulation of collagen IV, which had caused the vessel wall to thicken. Immunofluorescence for detection of immune reactants was negative. It was concluded that the histomorphology of PCT of long duration may be similar to that of scleroderma. Nevertheless, in addition to clinical findings, detailed skin biopsy studies including contemporary techniques can contribute to the differentiation of these diseases.