Dermatitis por Toxicodendron striatum ("manzanillo")

the case is described and discussed of a patient with contact dermatitis due to exposure to toxicodendron striatum or rhus striata, a tree known in some parts of colombia？s andean region as "manzanillo". this tree belongs to the anacardiaceae, a family of vascular plants whose sap has a large content of active principles. the noxious agent is urushiol, a mixture of alkylated ortho-benzenodioles or alkylated catechols, which can be saturated or unsaturated. urushiol is a colorless or pale yellow oil which is found in the plant？s leaves, stem and roots. the clinical picture begins with erythema, edema and formation of vesicles and papules. on occasion, extensive bullae can develop. these lesions are not confined to the contact zone, but appear on the rest of the skin, especially on skin folds. in the united states, this dermatitis is very frequent due to contact with other plants of the toxicodendron genus, such as poison ivy, poison oak and poison sumac. the mechanism of urushiol-induced injury is eminently immunological, although this condition is often referred to as dermatitis caused by poisonous plants or dermatitis venenata, as if it were caused by irritative contact. in central and south america, dermatitis caused by t. striatum is widely known and feared by farmers and people who work in the woods. recommended treatment is washing with abundant water and soap within the first four hours after contact. all contaminated objects should also be washed. pharmacologic agents do not significantly shorten the course of the illness. lesions disappear within one or two weeks. it is highly advisable for clinicians to familiarize themselves with the mechanisms of injury and to understand the importance of education for the control of this condition.