<unk>  is a small-vessel vasculitis in which complexes of immunoglobulin A (IgA) and complement component 3 (C3) are deposited on arterioles, capillaries, and venules (hence it is a type III hypersensitivity reaction). As with IgA nephropathy, serum levels of IgA are high in<unk>  and there are identical findings on renal biopsy; however, IgA nephropathy has a predilection for young adults while<unk>  is more predominant among children. Further, IgA nephropathy typically only affects the kidneys while<unk>  is a systemic disease.<unk>  involves the skin and connective tissues, scrotum, joints, gastrointestinal tract and kidneys. The genetic basis remains unclear except for involvement of the human leukocyte antigen region of the genome. It is hypothesized to involve autoimmunity triggered by infections, particularly Staphylococcus aureus, Mycoplasma and adenovirus.
Henoch–Schönlein purpura
Chronic testicular pain
Amyloid purpura
Testicular pain
Golfer's vasculitis
Hennekam syndrome
Roussy–Lévy syndrome
Solar purpura