26th April 2024

A 9-year-old boy is brought to the clinic by his parents due to a rash that appeared suddenly on his lower legs and buttocks.

A 9-year-old boy is brought to the clinic by his parents due to a rash that appeared suddenly on his lower legs and buttocks. The rash is non-blanching and predominantly consists of palpable purpura. He also complains of mild joint pain in his knees and ankles. His parents mention he had a mild upper respiratory infection two weeks ago. There are no significant past medical histories or medication use. On examination, the child appears otherwise well, without abdominal pain or renal involvement signs.

Which is the most likely diagnosis?