Mark, a 30-year-old engineer, presents to his GP with a progressively worsening localised itchy rash on the dorsum, medial and lateral aspects of the left ankle on the background of an ankle injury approximately one month prior.

The rash began five days ago. Mark reports experiencing an exacerbation of allergic rhinitis, with clear rhinorrhoea and itchy eyes, the day before rash onset.

These symptoms have since resolved, and the rash is now the key symptom of concern.

Mark sustained the ankle injury in a mountain bike accident one month ago.