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History
An 18-year-old girl develops a widespread rash 5 days after a sore throat. She had pre-sented in a similar way 2 years ago to her GP who treated her with antibiotics and the rash had faded. She does not feel unwell in herself and has no other symptoms.
Examination
There are multiple erythematous small dis-crete plaques and papules with overlying scale predominantly over her trunk but also affecting her limbs (Fig. 13.1). Her face and scalp have been spared. Her nails are nor-mal. Examination of her throat reveals some erythema over her pharynx, but no pustules are seen.
Questions
• What is the most likely diagnosis?
• How would you manage her?
• What is the prognosis?
Medicine
This patient is suffering from guttate psoriasis. This is a scaly skin eruption that appears rapidly after the onset of a streptococcal throat infection. This type of psoriasis is pre-dominantly seen in adolescents and young adults. The word guttate is derived from the Latin name gutta which means ‘drop-like’. The differential diagnosis includes Pityriasis rosea. Classically, in guttate psoriasis lesions are symmetrical mainly over the trunk and limbs with crops of papules and small plaques with overlying scale. Throat swabs may confirm the presence of group A -haemolytic Streptococcus. Blood tests may reveal an increased antistreptolysin titre. Patients with guttate psoriasis respond well to phototherapy. Mild topical steroid can be used but it is challenging to apply the medicated ointment accurately to the affected skin only. As a general rule thin plaques of psoriasis respond well to ultraviolet B (UVB) light and thicker plaques respond to UVA light given with oral psoralen (PUVA). This patient’s throat swab confirmed a streptococcal infection and she was therefore treated with 10 days of erythromycin antibiotics. It is thought that treating the underly-ing bacterial infection can shorten the length of the skin eruption. Her skin cleared with narrow-band UVB phototherapy (TL-O1) given three times per week for 4 weeks. Occasionally, guttate psoriasis can evolve in some patients into chronic plaque psoria-sis, many of whom have a positive family history of psoriasis. The majority of patients, however, are clear of the lesions after a few weeks. Patients may have recurrent ‘attacks’ associated with bacterial throat infections, as in this case.
KEY POINTS
• Guttate psoriasis often is associated with a preceding streptococcal throat infection.
• It is predominantly seen in adolescents and young adults.
• Patients with guttate psoriasis respond well to phototherapy.
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