Phytophotodermatitis induced by wild parsnip.

Phytophotodermatitis results when skin is exposed to ultraviolet light after previous contact with a phototoxic compound. Wild parsnip (Pastinia sativa), a member of the Umbelliferae family, is an invasive plant species introduced to North America as a root vegetable. Although cultivated less commonly today, the plant is increasingly found growing wild in prairies and roadsides. The stems and leaves contain furocoumarins, which upon activation by UV light interact with oxygen. Resultant reactive oxygen species induce tissue damage manifesting initially as blistering and later as hyperpigmentation. We report the case of a woman who developed phytophoto-dermatitis after encountering wild parsnip on a midwestern prairie.