An ulcerated lesion in a previously well child.

A previously well 6-year-old girl was referred to clinic with a 5-month history of an ulcerated lesion on her left forearm after sustaining an insect bite in Iraq, having recently emigrated to the UK. The lesion was initially painful and later became ulcerated, pruritic and inflamed. She previously received treatment with topical corticosteroid with no improvement. There were no systemic symptoms of fever, weight loss or night sweats. She had no significant medical history, no allergies or regular medication. Her vaccinations were up to date including BCG. There was no known exposure to tuberculosis and no other family members were affected. Examination revealed a well-grown child with height and weight >25th centile. Systems examination was unremarkable with no lymphadenopathy or organomegaly. An ~2×3 cm erythematous plaque on the left dorsal forearm was noted (figure 1). Initial investigations revealed a normal Full Blood Count, Urea & Electrolytes and Liver Function Tests and negative tests for HIV and Hepatitis B & C. Mantoux was 0 mm, Quantiferon (IGRA) negative and chest X-ray was normal. Figure 1 Initial clinical findings demonstrating an erythematous plaque with central ulceration and crusted scab on the left dorsal forearm. 1. Which of the following …