A healthy 4-year-old girl came to the Emergency Department with a 1-week history of an itchy and painful skin rash on the palm of her right hand. Initially, the rash was vesicular and associated with a fever that started 48 hours before. Epidemiological context was relevant for a recent 2 month-visit to Guinea-Bissau, where she had contact with sandy areas.
Upon observation, she presented an erythematous, painful lesion, approximately 1 cm wide and 2 cm long, on the palm of her right hand, adjacent to a lesion with whitish relief and a serpentine shape, measuring about 4 cm in length (Figure 1). Blood tests revealed an increase in C-reactive protein (3.72 mg/dL), a normal leukogram (no eosinophilia), negative blood culture, and negative anti-Toxocara spp-Larva Migrans Visceral antibody. The girl was prescribed flucloxacillin and oral antihistamine, and her condition was closely monitored. In the following days, the lesion acquired a migratory nature and increased in size (Figure 2).
Figure 1. Initial observation of the hand lesion.
Figure 2. The second observation of the hand lesion (one week later).
What is the diagnosis?