The sting of the Portuguese man-of-war. One of the most painful effects on skin is the consequence of attack by oceanic hydrozoans known as Portuguese men-of-war, which are amazing for their size, brilliant color, and power to induce whealing. They have a small float that buoys them up and from which hang long tentacles. The wrap of these tentacles results in linear stripes, which look like whiplashes, caused not by the force of their swing but from deposition of urticariogenic and irritant substances.
Polymorphous light eruption. Patients with this condition develop papules, papulovesicles, or erythematous plaques in response to sun exposure. The lesions erupt a few hours to several days after the subject has been exposed to sunlight. Lesions are most often located on the face, upper chest, and exposed parts of the extremities. Ocular inflammation and cheilitis may also occur. Among North American and Latin American Indians, polymorphous light eruption tends to be a familial disease with childhood onset.
Port-wine stain. This unilateral vascular malformation has a markedly different histology, significance, and natural history from that of the salmon patch. The port-wine stain is made up of capillary ectasias that may be present throughout the dermis and that gradually increase with age. The color changes from pink to purple as the patient grows, and the lesions may become nodular during adult life. Because port-wine stains show no tendency to involute, they may represent a significant, lifelong cosmetic problem.