[The morphology of skin damage in porphyria cutanea tarda (PCT)].
Skin biopsies (fresh and old blisters) of the back of the hand and lower arm, respectively, obtained from 24 patients with clinically and biochemically established porphyria cutanea tarda have been examined light and electron microscopically, 15 out of them also by immunofluorescence microscopy (occurrence of IgG, IgM and C3). Light microscopically there were subepidermal blisterings and typical corial broadenings of the capillary wall with deposits of diastase-resistant PAS-positive material in and around the walls of the vessels. Electron microscopically, replications of the capillary basement membrane with deposits of amorphous material were observed. IgG and C 3 on the dermoepidermal junction and in the capillaries could be identified by means of the direct immunofluorescence method in a number of cases. The pathogenesis of the lesions of the vessel walls and that of the subepidermal blistering, hitherto interpreted as their consequence, is not yet clarified sufficiently.