A 9-year-old girl presents to A&E with her mother with a 1 day history of a rash on her lower limbs. She has been recovering from a cold recently. She denies previous similar episodes. She limps whilst walking around the room and is gripping her abdomen in pain. On examination, there are no findings on auscultation of her chest. Her knee is tender but not visibly swollen. Her rash is palpable and purpuric bilaterally on her lower limbs. A urine dipstick reveals protein +++ and ++ haematuria.

Which of the following is the most likely diagnosis?

Options:
explanation: ITP is a disorder resulting in an isolated low platelet count and a tendency to bruise/bleed. A purpuric rash may be present but it is not typically palpable. Children may develop ITP post virally and recovery often occurs spontaneously. The additional clinical features here of joint pain and dipstick positive urine suggest an alternative diagnosis.
name: Immune thrombocytopenic purpura (ITP)
label: b
answer: no
explanation: Henoch-Schonlein Purpura is a small vessel vasculitis characterised by IgA deposition. It is associated with nephrotic and nephritic syndromes, as well as a rapidly progressive glomerulonephritis, due to glomerular IgA deposition. It presents with a triad of joint pain, abdominal pain, and palpable purpura.

A typical history involves a recent viral upper respiratory tract infection in a child, followed by the development of the characteristic clinical features. HSP is usually managed supportively as it often resolves spontaneously. Severe renal involvement (for example rapidly progressive, crescentic glomerulonephritis, or persistent nephrotic syndrome), or intractable symptoms not responding to analgesia may necessitate management with steroids.
name: Henoch-Schonlein Purpura
label: a
answer: yes
explanation: Microscopic polyangiitis is a small vessel vasculitis associated with p-ANCA. It is a systemic condition that can affect any organ including the lungs, kidney, skin and nervous system, and may present with a palpable purpuric rash. However, the clinical features here are that of HSP, with a classical triad of abdominal pain, joint pain, and purpura, in a child who has recently recovered from a viral infection.
name: Microscopic polyangiitis
label: e
answer: no
explanation: This is incorrect because meningitis classically presents with a fever, headache, photophobia and neck stiffness. It can be difficult to elucidate these symptoms in children so it is important to distinguish between a vasculitic rash compared to a non-blanching purpuric rash in meningitis. There is increased awareness and education amongst parents about how to use the glass test to determine if their child's rash is non-blanching.
name: Meningitis
label: d
answer: no
explanation: This is incorrect because ALL presents with symptoms of anaemia, infection and bleeding. This is secondary to bone marrow failure. It can also present with infiltrative symptoms such as bony pain. It is very important to elucidate any red flag symptoms which point towards cancer such as weight loss or night sweats. The question stem points towards HSP due to the triad of proteinuria, joint pain and a palpable, purpuric rash.
name: Acute lymphoblastic leukaemia (ALL)
label: c
answer: no

Correct answer: a


Learning point: Henoch-Schonlein Purpura is a small vessel vasculitis in children, presenting with a triad of joint pain, abdominal pain, and palpable purpura.