A 38-year-old woman twisted her right ankle and applied a Chinese medicine patch to relieve the pain. The following day the patient developed a severe contact dermatitis (CD) with many small vesicles (<5 mm)="" and="" bullae="" (="">5 mm) (Figure 146-1). The erythema had a well-demarcated border and was traced by the doctor's pen. Cold compresses and a high potency topical steroid were prescribed. When the patient showed little improvement a 2-week course of oral prednisone was given starting with 60 mg daily and tapering down to 5 mg daily. The patient responded rapidly and the CD fully resolved.1,2
Severe acute allergic contact dermatitis on the ankle of a woman after application of a Chinese topical medicine for a sprained ankle. (With permission from Milgrom EC, Usatine RP, Tan RA, Spector SL. Practical Allergy. Philadelphia, PA: Elsevier, Inc; 2004.)
CD is a common inflammatory skin condition characterized by erythematous and pruritic skin lesions resulting from the contact of skin with a foreign substance. Irritant contact dermatitis (ICD) is caused by the non-immune-modulated irritation of the skin by a substance, resulting in a skin changes. Allergic contact dermatitis (ACD) is a delayed-type hypersensitivity reaction in which a foreign substance comes into contact with the skin, and upon reexposure, skin changes occur.3
- Some of the most common types of CD are secondary to exposures to poison ivy, nickel, and fragrances.4
- Patch testing data indicate that the five most prevalent contact allergens out of more than 3700 known contact allergens are nickel (14.3% of patients tested), fragrance mix (14%), neomycin (11.6%), balsam of Peru (10.4%), and thimerosal (10.4%).5
- Occupational skin diseases (chiefly CD) rank second only to traumatic injuries as the most common type of occupational disease. Chemical irritants such as solvents and cutting fluids account for most ICD cases. Sixty percent were ACD and 32% were ICD. Hands were primarily affected in 64% of ACD and 80% of ICD4 (Figure 146-2).
Occupational irritant contact dermatitis in a woman whose hands are exposed to chemicals while making cowboy hats in Texas. (Courtesy of Richard P. Usatine, MD.)
- CD is a common inflammatory skin condition characterized by erythematous and pruritic skin lesions resulting from the contact of skin with a foreign substance.
- ICD is caused by the non-immune-modulated irritation of the skin by a substance, resulting in a skin rash.
- ACD is a delayed-type hypersensitivity reaction in which a foreign substance comes into contact with the skin, and is linked to skin protein forming an antigen complex that leads to sensitization. Upon reexposure of the epidermis to the antigen, the sensitized T cells initiate an inflammatory cascade, leading to the skin changes seen in ACD.