Henoch Schonlein Purpura
Henoch Schonlein Purpura (HSP) - is very common and characterized by palpable purpura over extensor surfaces (typically the legs and buttocks), abdominal pain (can be with haematochezia), renal involvement (haematuria) and lower limb large joint arthritis (ankles and knees).
Most children recover completely within 4 weeks but recurrences can occur and renal involvement can progress to renal failure. NSAIDS are helpful for the joint pain and corticosteroids may be used when there are gastrointestinal symptoms although there is little evidence that steroids alter the disease course or prevent severe renal disease.
Arthritis and arthralgias occur in 50-80% of children with HSP- in 25% of cases, joint involvement can be the presenting feature of HSP.
HSP arthritis is predominantly a large joint arthritis involving knees, ankles, however other joints such as wrists, elbows and small joints of fingers can also be involved. Affected joints have painful ranges of movement due to periarticular swelling but the characteristic findings of warmth, erythema and effusion are often absent. Joint disease in HSP is transient and resolves within few days to weeks without any residual damage. Articular features may reappear for few weeks and subside. NSAIDs may be used.
The photograph below shows the typical palpable purpura of HSP