Case 42: Sudden rash
Tuesday, January 31st, 2012Author: Dr Ian Stell
A 40 year old male presented with a 24 hr history of a widespread rash. This started on his legs before spreading to his abdomen, chest and back. The small (up to 2 cm) lesions were slightly scaly, and a little itchy, but he felt well. He had not been well about a week earlier with a sore throat, and a productive cough.
He had suffered a similar attack of the same rash about two years previously, which had cleared over several weeks after treatment.
1. What is the diagnosis?
Click to see the answerThis is guttate psoriasis. This characteristically develops as a sudden onset rash, of ‘salmon coloured’ slightly scaly, slightly itchy spots. They have a sharp edge, with healthy skin in between. The spots are primarily focussed on the trunk and proximal limbs.
80% of these rashes have a proceeding streptococcal infection 2-3 weeks earlier, although other infections have also been linked to it. It is also linked to plaque psoriasis, and an HLA susceptibility has been identified. It usually affects young people aged 10-40 years.
2. What is the prognosis?
Click to see the answerAbout two-thirds resolve spontaneously over weeks to months. Better prognosis is linked to younger age, and a high ASO titre.
3. What treatment could be effective?
Click to see the answerAs for plaque psoriasis, exposure to sunlight helps, as does UVB treatment, topical steroids or coal-tar preparations. In rare severe cases immunosuppressant drugs may be needed. Clearance of chronic streptococcal carriage in the throat can also help.