Plant Contact Dermatitis

Abstract

Plant contact dermatitis, that is of the great clinical concern, is caused by contact with flowers, trees, grass, fruits, weeds, vegetables, and pollens. The contact with these agents is direct (the most frequent) or indirect through medicaments and cosmetics containing plant extracts, or various plant-based foods, industrial products, and herbal remedies (less frequent). Responsable of phyto- and phytophotocontact dermatitis are various plant families with their numerous irritant and/or sensitizing chemicals. The irritant forms of contact dermatitis can be of a mechanical (owing to the presence of prickles, spines, and thorns) or chemical (fluids and crystals in the different portions of the plant) nature. A characteristic picture of allergic contact dermatitis, usually of occupational origin, is the eczema of the fingertips with fissured, hyperkeratotic and painful lesions, observed in tulip pickers and in people handling bulbs and garlic. Some plants (walnut, henna) can induce a primary contact hyperpigmentation. The combined action of various plants (Umbelliferae, Rutaceae, Moraceae, etc.) on the skin and the exposure to the sun is the cause of the photophytocontact dermatitis. The phototoxic contact reactions presents with different clinical pictures: a classic eczematous eruption, the dermatitis bullosa striata pratensis, and the berloque dematitis. Some cases of photoallergic contact reactions to furocoumarins are reported. Frequently reported are also cases of phytoairborne allergic contact dermatitis. The clinical-etiological and botanical investigation of plant contact dermatitis is often very difficult, since it is necessary to take into account the patient’s occupation, hobbies, any recent outdoors excursions, and the identification of the species of the plant. Finally, it is important to consider the possible evidence of a pseudophytodermatitis linked to contact with parasites (mites), that infest plants or their products.