Release of prostaglandin D2 and histamine in a case of localized heat urticaria, and effect of treatments.

A case of localized heat urticaria in a 70-year-old woman is reported. Increased plasma levels of prostaglandin D2 and blood histamine after heat challenge indicate a role for mast cell degranulation in the pathophysiology of the syndrome. Treatment with astemizole increased the temperature threshold to wealing, but not to itch or erythema. The patient was partially desensitized by repeated exposure to heat and this was further improved by indomethacin. After treatment there was no increase in plasma prostaglandin D2 on challenge. No evidence was found for the activation of the alternative complement pathway.