Henoch–Schönlein purpura

Henoch-Schönlein purpura (HSP) is a common vasculitis of childhood with predominant involvement of small blood vessels. It often follows an upper respiratory tract infection or can be caused by medication. Vasculitis mainly affects the blood vessels of the skin, digestive system, kidneys and joints. Immunofluorescence deposits of IgA immunocomplexes are typical.

Characteristics
The most common occurrence is in children from 3 to 15 years of age.  Incidence  is 12/100, boys are more likely to be affected than girls. The cause is unknown (undeniable role of intercurrent infection).

Leukocytoclastic vasculitis (biopsy of skin lesions) is characteristic. IgA deposits occur in capillaries and venules, and in the kidneys, they are mesangioproliferative deposits glomerulonephritis.

Clinical picture
The patient suffers from a skin rash, either as a confluent skin eruption of the nature of purpura above the extensors of the lower limbs, which may also occur on the upper limbs or as hemorrhagic bulla). The rash does not itch and disappears within 2 weeks.

Up to  80% of patients also experience joint pain, transient arthritis, prevents rash, but can affect any joint - especially the knees and ankles, with arthritis onset swelling with pain and reduced mobility.

In 50% of patients, abdominal pain occurs, especially in the navel area, and positive occult bleeding may occur.

In 1/3 patients there is kidney disease of various extents - glomerulonephritis, which is microscopic hematuria and proteinuria, which rarely progresses to nephrotic syndrome)

Laboratory finding
Elevation of inflammatory parameters occurs in the laboratory finding: sedimentation, CRP, leukocytosis. Platelet counts, in contrast to platelets, are normal or elevated. Hematuria, proteinuria and faecal blood may be present. Elevation occurs PAF. Anemia appears. Elevations in IgA persist, complement levels tend to be normal. In hemocoagulation there is usually a pathological test of capillary fragility, other parameters are normal. Mesangioproliferative glomerulonephritis with IgA deposits and complement in the mesangium occurs during biopsy kidneys and IgA deposits during skin biopsy.

Diagnostic criteria
In order to diagnose Henoch-Schönlein purpura, the patient must have 2 of the following 4 symptoms:
 * purpura that does not disappear on palpation (in the absence of thrombocytopenia);
 * abdominal pain (diffuse pain or intestinal ischemia);
 * diagnostic biopsy (granulocytes in the arterioles and venules);
 * age up to 20 years.

These criteria have 87.1% sensitivity and 87.7% specificity.

Differential diagnostics

 * Another systemic vasculitis (Wegener's granulomatosis, polyarteriitis nodosa, systemic lupus erythematosus, dermatomyositis, juvenile rheumatoid arthritis, Kawasaki disease, etc.) ;
 * thrombocytopenic purpura (idiopathic thrombocytopenic purpura, leukaemia).

Therapy
The most important is sleep mode. So-called symptomatic therapy is proposed, which involves hydration and adjustment of electrolyte balance. In acute arthritis, non-steroidal anti-rheumatic drugs are prescribed. Corticosteroids are given to the patient for joint symptoms and abdominal pain. Methylprednisone is originally given, but not as prevention for glomerulonephritis, as meta-analyses have not shown a reduction in the risk of developing nephrotic or nephritic SY with preventive use. In the case of an RPGN image, a combination of steroids and azathioprine is appropriate.

Forecast
The long-term prognosis is favourable, but it depends on the extent of renal impairment.  1–4% of patients  may develop chronic nephritis. . The disease usually lasts 3-4 weeks.

Related articles

 * IgA nephropathy
 * Vaskulitis
 * Manifestations of inflammatory rheumatic diseases on the musculoskeletal system and their surgical treatment