The patient
This woman was in her late 60s and often dyed her hair.
A sore, red band had developed just under her hairline on her forehead, and was spreading down beside her ears.
Initially, I thought the diagnosis was simple – a reaction to her hair dye. So she agreed to stop using it.
Several weeks later she returned with these colourful, variable, sore lesions all over her face and neck, and I had no idea what they were.
Differential diagnoses
- Annular psoriasis
- Dermatitis artefacta
- Cutaneous lupus erythematosus
Psoriasis gets more complicated every time I read about it. The typical, easily recognisable plaques are only a fraction of what psoriasis actually comprises.
Annular psoriasis was a suggestion by our local dermatologist. It produces circular lesions, but is usually associated with pustular psoriasis which occurs on the palms and soles.
Most GPs will find it difficult to be shocked by almost anything a patient does, and I did wonder whether this woman was deliberately applying a corrosive substance to her face.
Lupus erythematosus of the skin is an umbrella term including discoid lupus, subacute lupus and lupus panniculitis to name just a few. Lupus is an autoimmune condition involving antibodies to cell nuclei.
Getting on the right track
Even our very experienced dermatologist requested a skin biopsy, which showed that the problem was subacute lupus.
Thankfully the patient had no systemic signs of lupus. Six months later she was almost entirely better on hydroxychloroquine and low-dose prednisolone.
In retrospect, I had omitted a vital question from the history – I didn't ask about sunlight.
Her lesions got worse out in the sun and when driving – psoriasis gets better with sunlight.
