Whose Skin Is Harmed by Sunlight?

This 50-year-old lady has noticed blisters on her nose, forehead, and dorsa of her hands associated with hirsutism of the eyebrows and temples. Her normally gray hair has commenced to turn black again. She takes barbiturates routinely for insomnia. A red fluorescence of the urine when examined under a Wood's light demonstrates the presence of porphyrins and confirms the suspicion of porphyria cutanea tarda, in which photosensitizing circulating porphyrins result in a phototoxic (exaggerated sunburn) effect. The eyelids, submental area, and upper lip are relatively unexposed to direct sunlight and are correspondingly uninvolved.

A 30-year-old woman in good health suddenly developed swelling and vesiculation of the eyelids and cheeks associated with considerable pruritus after clearing brush in direct sunlight. The linear arrangement of the vesicles plus the erythema and edema of the loose periorbital tissue (which is under the frontal shelf and thus relatively unexposed to light) points to a