Henoch-Schonlein purpura (IgA vasculitis)

What it is

Henoch-Schonlein purpura, also known as IgA vasculitis, is a small vessel vasculitis that primarily occurs in children. The small vessel group also contains Wegener granulomatosis, microscopic polyangiitis, the Churg-Strauss syndrome and cryoglobulinemic vasculitis. It is the combination of some of the following features: a characteristic skin rash (purpura), arthralgia, periarticular oedema, abdominal pain, and glomerulonephritis. IgA deposition underlies it, and its renal lesion is the renal pathology of IgA nephropathy (Berger disease). HSP = Has Stomach Pain. It is also termed anaphylactoid purpura. Its rash is a non-blanching purpura, and its renal lesion is an IgA nephritis.

It is the most common vasculitis of childhood, and it usually occurs between the ages of 3 and 10 years.

Causes and risk

It follows a recent URI, with B19 and GaS named as the preceding infections. IgA nephropathy, with which HSP has considerable pathological overlap, develops 1-2 days after a URTI, while post-streptococcal glomerulonephritis develops 1-2 weeks after. The infection that comes before it is the URI, and that is the preceding infection to name for HSP: and the exam clue puts the purpura on the legs, the abdominal pain and the hematuria after it. Its cause is unknown, and it is thought to be postinflammatory. The organism most frequently associated with it is Campylobacter jejuni, but this is found in only a minority of cases.