Henoch–Schonlein¨ Purpura
A syndrome resulting from a vasculitis of small blood vessels.
Peak 2–8 years, young adults.
2M : 1F
The aetiology is unknown but several factors have been implicated including upper respiratory tract infection especially by Streptococcus. Serum concentrations of IgA are raised in approximately half of patients and IgA-containing immune complexes have been identified. Clusters of cases have been noted with no obvious precipitant.
The condition results from inflammation within the walls of small blood vessels, predominantly capillaries but small arterioles and venules are also affected. The inflammation is thought to be the result of a hypersensitivity reaction (type III immune complex mediated). The inflammation of the vessels increases permeability resulting in a leaking of fluid and cells from the circulation into the surrounding tissue. IgA deposition within the glomeruli of the kidney causes a focal segmental pattern of glomerulonephritis with a resultant proliferation of mesangial cells and a nephritic syndrome.
This multisystem disorder may occur with simultaneous or sequential manifestations:
The characteristic presentation is with the skin lesion. It is unclear whether other lesions can occur without the rash. The rash characteristically affects the lower limbs and buttocks, but is not always confined to these areas. The rash is initially blanching but becomes purpuric and then goes through the classic colour changes of a bruise, lesions of varying ages are present at one time. Oedema of the face, dorsum of the hands and feet, perineum or foreskin may occur especially in young children
A self-limiting acute arthritis of large distal joints occurs without articular damage with the patient complaining of swollen, tender painful joints exacerbated with movement.
The gastrointestinal manifestations present with colicky pain, which may be severe, and associated with vomiting. Bleeding from the affected vessels may cause melaena or haematemesis.
Renal involvement is common with haematuria and proteinuria detectable but is generally not severe in children.
Rarely there may be CNS involvement with convulsions, paresis and coma.
There is an inflammatory infiltrate in the upper dermis, joint lining and GI mucosa and glomerular mesangium with neutrophils and extravasated red blood cells.
Gastrointestinal complications include infarction and intussusception as a result of oedema. Renal failure may occur in the acute phase, or may progress over many years.
The diagnosis is clinical; erythrocyte sedimentation rate, white cell count and eosinophils may be raised. Urine microscopy should be performed looking for red and white blood cells, casts and protein. Faecal occult blood may be positive without overt bleeding.
No specific treatment is used. Symptomatic relief of joint pain and rash may be achieved with nonsteroidal anti-inflammatory drugs. Gastrointestinal bleeding and CNS manifestations may be improved with the prompt use of steroids. Complications such as acute renal failure and intussusception should be managed promptly.
In most cases the overall prognosis is excellent, the course is variable with cases lasting between a few days and a few weeks. Rarely it may continue for up to a year and there may be a course of relapse and remission. Severe renal involvement and CNS involvement may be life-threatening.
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