Immediate and delayed skin allergy from cow dander

image: Cow dander is the most common cause of occupational contact urticaria in Finland. Occasionally cow dander also causes allergic contact dermatitis, which can be revealed by patch testing with cow dander. image: A patient with a combined type I and type IV allergy to cow dander is the subject of this report. image: She had intense pruritus, whealing, and severe dermatitis, but no respiratory symptoms. Skin test and radioallergosorbent test indicated that she had both type I and type IV allergy to cow dander. image: Increasing numbers of cases with both type I and type IV allergy are reported, but the mechanism is not clear. In our clinic, we classify immediate reactions as contact urticaria if the clinical picture involves whealing, and as protein contact dermatitis if dermatitis dominates the clinical picture. If delayed allergic patch test results are obtained, we consider it allergic contact dermatitis.