Clinical Features

Symptom onset often 1–3 weeks after an infection, typically affecting the upper respiratory tract [

• Skin: (∼ 100% of cases)

  • Symmetrically distributed, raised, erythematous macules or urticarial lesions that coalesce into palpable purpura (nonblanching skin lesions)

  • Most common sites: the lower extremities, buttocks, and other areas of pressure or constraint (e.g., from socks or clothing)

• Joints: (∼ 75% of cases) arthritis/arthralgia, most common in the ankles and knees

• Gastrointestinal tract (∼ 60% of cases)

  • Colicky abdominal pain (may be severe enough to mimic an acute abdomen)

  • Can cause intussusception

  • Bloody stools or melena

  • Nausea/vomiting

• Kidneys (∼ 50% of cases): IgAV nephritis with signs and symptoms of nephritic syndrome

• Other organs

  • Scrotum (scrotal swelling, pain, and tenderness)

  • Central and peripheral nervous system (e.g., headaches, seizures, focal neurologic deficits, ataxia, intracerebral hemorrhage, central and peripheral neuropathy)

  • Respiratory tract (e.g., mild interstitial changes, pulmonary hemorrhage)

  • In rare cases: eyes (e.g., keratitis, uveitis)