Author(s): Dr Ian Coulson, Dermatologist.
Edited by the DermNet content team.
This 70-year-old lady has developed an itchy eruption on her forearms, neck, and face. She has arthritis.
There is a confluent red and scaly eruption symmetrically affecting the forearms with a sharp cut-off just above the elbows. The face and the area of the chest are affected.
The distribution suggests either an airborne contact allergy or photosensitivity.
In a photosensitive eruption, the skin immediately behind and below the ears, the upper lids and between the fingers is often unaffected as these are relatively light-shielded areas. In contrast, with an airborne contact dermatitis, these light-shielded areas are often affected.
A photosensitive eruption should immediately arouse the suspicion of drug-induced photosensitivity. In this case, she had recently started a non-steroidal anti-inflammatory agent just before the onset of good summer weather. This was withdrawn and she was given a topical steroid cream and advice to keep out of the sunshine. As the condition improved and she was able to go out, she used a broad spectrum sunscreen with good UVA protection (most drug-induced photosensitivity is the result of sensitivity to UVA)
