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It is associated with palpable purpura (small hemorrhages); often with joint and abdominal pain. More often affects children, but can be seen in adults.
What is Henoch–Schönlein purpura? It is named after Eduard Heinrich Henoch (1820–1910), a German pediatrician and his teacher Johann Lukas Schönlein (1793–1864), who described it in the 1860s. Schönlein associated the purpura and arthritis, and Henoch the purpura and gastrointestinal involvement. The English physician William Heberden (1710–1801) and the dermatologist Robert Willan (1757–1812) had already described the disease in 1802 and 1808, respectively, but the name Heberden–Willan disease has fallen into disuse. William Osler was the first to recognise the underlying allergic mechanism of HSP.