Toxicodendron (Rhus) Allergic Contact Dermatitis: (Poison Ivy, Oak, or Sumac)

Presentation

The patient is troubled with an intensely pruritic rash that often consists of raised lesions that develop into vesicles and are usually formed in a streaked or linear pattern. Eventually there is a weeping, honey-colored crust, confluence of vesicles, and (sometimes) large bullae ( Fig. 184.1 ). If involvement is severe, there may be marked edema, particularly on the face, periorbital areas ( Fig. 184.2 ), and genital areas. The thick protective stratum corneum of the palms and the soles generally protects these areas. Inflammation usually peaks in 5 days, evolving into a subacute phase in which the swelling and blistering subside, replaced by drier crust and scaling. Redness and itching persist. Secondary bacterial infection can develop, often caused by the patient’s scratching.

The patient is often not aware of having been in contact with poison ivy, oak, or sumac but may recall working in a field or garden from several hours to 4 days before the onset of symptoms. In general, the shorter the reaction time, the greater the degree of the individual’s sensitivity, which decreases with age. Most cases of Toxicodendron dermatitis begin to dissipate after 10 to 14 days.