Phytodermatitis Slides 16 through 20

Reprinted with permission from the American Academy of Dermatology. All rights reserved. Please note that the slides are very large JPEG files that will take up to 6.5 minutes to view or download using a 28.8 kbps modem.

Phytophotodermatitis

Skin reactions are caused by furocoumarin chemicals in the plant and exposure to Ultraviolet A sunlight. Blisters form in a few hours after contact with the plant and sunlight. Hyperpigmented skin develops in the affected area after the blisters have healed and may last for months.

Slide 16

Severe blistering reactions develop from exposure to the sap of the giant hogweed (Heracleum mantegazzanium).

Giant hogweed (Heracleum mantegazzanium)

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Slide 17

The gas plant or burning bush (Dictamnus albus) secretes a volatile oil that can be ignited with a match. This plant family also includes citrus plants such as lime, lemon and bergamot orange that also have phototoxic oils.

Gas plant (Dictamnus albus)

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Allergic Contact Dermatitis

Allergic contact dermatitis requires previous sensitization to low molecular weight compounds in a plant. Not everyone develops an allergic reaction to these compounds. The most common plant causing this reaction is poison oak or ivy. The large family of plants, Compositae, contain chemicals called sesquiterpene lactones, which are sensitizers and irritants. Most of these rashes are chronic, eczematous rashes as compared to the severe blisters that develop from contact with the poison oak or ivy plants. Allergic contact dermatitis is the least common type of plant reaction except for problems with poison oak or ivy.

Slide 18

Poison oak or ivy dermatitis can result in large tense bullae on the skin wherever there is contact with the urushiol oil in the plant. All parts of the plant contain the oil. The oil is active in the live and dead plants. It can remain intact on the surface of objects for years such as boots, clothing, camping equipment and can contaminate the fur of animals. Burning the plant causes severe eye and respiratory problems.

Poison oak or ivy dermatitis

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Slide 19

Poison oak or ivy dermatitis. Both plants contain urushiol oil and cause the same type of bullous reaction. The poison sumac plant in the southeastern United States also causes the same reaction.

Poison oak or ivy dermatitis

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Slide 20

Note how the poison ivy rash develops in linear streaks where the plant came in contact with the skin.

Poison oak or ivy dermatitis

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