BLACK-SPOT POISON IVY
By Gary M. White, MD
Black-spot Poison Ivy (BSPI) is a "pseudo" skin condition in which black spots develop on the skin in a patient recently exposed to poison ivy. The color results from the urushiol sap turning black in the presence of oxygen and moisture via a dopa oxidase-mediated oxidation.
- Occasionally BSPI is confused with melanoma.
- The black-spot test can be used by botanists to identify Toxicodendron species because the sap will turn black when expressed on white paper after a few minutes.
Small black dots on the skin that can be scraped off are characteristic of black-spot poison ivy.
Dermatology Online Journal 18(10)
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