The microscopic anatomy of the cutaneous changes in patients with active porphyria cutanea tarda (PCT) (22), inactive (postphlebotomy) PCT (ten), erythropoietic protoporphyria (five), variegate porphyria (two), and coproporphyria (one) were examined with light microscopic, fluorescent microscopic, and electron microscopic (EM) techniques. Characteristic changes common to the porphyrias studied included deposition of PAS-positive diastase-resistant mucopolysaccharides and immunoglobulins in and around the superficial dermal blood vessels. Reduplication of the vascular basal lamina and the extensive perivascular deposition of a fine fibrillar material were the most prominent EM features. These results indicated that the vascular abnormality was due to structural alterations as well as deposition of materials from the circulation. Distribution of the changes emphasizes the importance of the prophyrins and sunlight in development of the cutaneous damage noted in these porphyric states.
Epstein JH, Tuffanelli DL, Epstein WL. Cutaneous Changes in the PorphyriasA Microscopic Study. Arch Dermatol. 1973;107(5):689-698. doi:10.1001/archderm.1973.01620200007002