Electron Microscopy of the Skin in Erythropoietic Protoporphyria

SUMMARY. —An electron microscopical examination has been made of skin from 4 patients with erythropoietic protoporphyria. Both exposed areas and skin usually covered by clothing were studied. In exposed skin from the knuckle and dorsum of the hand the main abnormality is associated with small blood vessels in the upper part of the dermis. The amorphous material seen on light microscopy is found to consist of a multilayered partially fragmented basement membrane, and finely fibrillar material of moderate electron density which permeates and surrounds the vessel walls. The presence of this substance in the vessel walls and its abrupt junction with the normal dermal connective tissue supports the idea that it is derived from constituents of the blood or from the vessels themselves rather than by degeneration of dermal connective tissue. Nothing abnormal is seen in covered skin from the back.