iatroX Rounds #37
The clues
- 1
A 6-year-old boy is brought to the emergency department with a widespread non-blanching rash that appeared over the last 24 hours.
- 2
The rash is primarily distributed across the buttocks and the posterior aspects of the lower legs, with notable sparing of the trunk and face.
- 3
The child's parents note that he has been reluctant to walk due to pain in his ankles and has complained of intermittent abdominal cramps.
- 4
He remains systemically well and apyrexial, though his parents recall he had a runny nose and sore throat approximately ten days ago.
- 5
Urine dipstick reveals macroscopic haematuria and 2+ proteinuria, while a full blood count shows a normal platelet count and normal clotting screen.
- 6
Biopsy of the affected skin or kidney demonstrates a leukocytoclastic vasculitis with prominent deposition of immunoglobulin A and C3.
Henoch-Schönlein purpura is a systemic, small-vessel vasculitis that most commonly affects children following an upper respiratory tract infection. It is characterised by a classic tetrad of palpable purpura, arthralgia, abdominal pain, and renal involvement.
- Palpable purpura in a gravity-dependent distribution, usually on the legs or buttocks
- Normal platelet count is essential to differentiate it from thrombocytopenic purpura
- Risk of intussusception due to bowel wall oedema and haemorrhage
- Renal involvement is histologically identical to IgA nephropathy
for education and entertainment. not medical advice.