Tips on diagnosing vasculitis
WHEN examining bleeding into the skin like this, feel to see if it is flat or slightly raised. If raised, it is palpable purpura, and signifies a vasculitis. If there is sufficient vascular damage to cause bleeding into the skin, then the same thing may be happening with vessels in other organs.
A simple test is to see if there is blood in the urine, which would indicate systemic vasculitis. An important initial consideration is meningococcal septicaemia, where the patient will have a fever, neck stiffness and be systemically unwell.
On excluding that diagnosis, take a skin biopsy.