Theo is a 15-year-old boy brought in by his parents with 24 hours of spreading painful rash, with associated fever and fatigue. 

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<p>Theo is a 15-year-old boy brought in by his parents with 24 hours of spreading painful rash, with associated fever and fatigue.</p><p>Two weeks previously, Theo’s dermatologist had started him on oral upadacitinib (Rinvoq) 15mg daily for severe, widespread atopic dermatitis.</p><p>Theo is otherwise well, with no history of allergy or asthma, and up to date with all routine immunisations.</p><p>He has never had a rash like this previously.</p><p>Physical examination reveals Theo is febrile at 38.2°C with otherwise normal vital signs and appears euvolaemic.</p><p>There are disseminated vesicles, some with central erosion, over the neck, anterior trunk and upper limbs (pictured).</p><p>He has associated tender cervical lymphadenopathy.</p>

Dr Kate Kelso is a GP and medical editor at Australian Doctor.