Henoch-Schonlein Purpura (aka. Anaphylactoid purpura) is a small vessel vasculitis.
Background:
most commonly diagnosed vasculitide in childhood
age range 3-15 years, mean age 4yo, mostly <7yo (75% cases)
more cases in Winter and Spring months
boys more commonly than girls (2:1)
IgA-mediated leukoclastic vasculitis
Clinical Features:
Rash: progresses to petechiae, purpura; occurs on lower extremities and buttocks in dependent areas
Joints: arthritis/arthralgia mainly of large joints (knees, ankles)
GI: colicky abdominal pain, may occur with melena (33%) or less likely, hematemesis; ultrasound for intussusception (2-14%)
Renal: microscopic hematuria with/without proteinuria; usually transient but may lead to progressive renal disease in patients with more severe, persistent symptoms
Orchitis and/or angioedema may also occur
Etiology:
unknown
preceding URI (50%)
associated with bacteria (Strep pyogenes, Legionella, Mycoplasma), viruses (EBV, CMV, parvovirus), drugs (penicillin, cephalosporins), and insect bites
Diagnosis:
clinical features
lab studies that are helpful but nonspecific: high WBC, high ESR, high IgA, normal platelet and coagulation studies
Treatment:
supportive care, may last up to 4 weeks
steroids may be helpful but evidence has not shown true benefit
