Henoch-Schönlein Purpura (Anaphylactoid Purpura)

Key Features

Essentials of Diagnosis

• Purpuric cutaneous rash

• Migratory polyarthritis or polyarthralgias

• Intermittent abdominal pain

• Nephritis

General Considerations

• Most common type of small vessel vasculitis in children

• Primarily affects boys 2–7 years of age

• Occurrence is highest in the spring and fall

• Upper respiratory infection precedes the diagnosis in two-thirds of children

• Antigens from group A β-hemolytic streptococci and other bacteria, viruses, drugs, foods, and insect bites have been proposed as inciting agents

Clinical Findings

Symptoms and Signs

• Skin involvement

  • May be urticarial initially

  • Progresses to maculopapules

  • Coalesces to a symmetric, palpable purpuric rash distributed on the legs, buttocks, and elbows

• New lesions may continue to appear for 2–4 weeks, and may extend to involve the entire body

• Migratory polyarthralgias or polyarthritis, primarily of the ankles and knees develop in two-thirds of patients

• Intermittent, sharp abdominal pain occurs in approximately 50% of patients, and hemorrhage and edema of the small intestine can often be demonstrated

• Intussusception may develop

• Renal involvement

  • Develops during second or third week of illness with either a nephritic or, less commonly, nephrotic picture in 25–50% of patients

  • May be accompanied by hypertension

• In males, testicular torsion may also occur

• Neurologic symptoms are possible due to small vessel vasculitis

Differential Diagnosis

• The rash of septicemia (especially meningococcemia) may be similar to skin involvement in Henoch-Schönlein purpura, although the distribution tends to be more generalized

• The possibility of trauma should be considered in any child presenting with purpura

• Other vasculitides should also be considered

• The lesions of thrombotic thrombocytopenic purpura are not palpable

Diagnosis

• Platelet count is normal or elevated

• Other screening tests of hemostasis and platelet function are typically normal

• Urinalysis frequently reveals hematuria and sometimes proteinuria

• Stool may be positive for occult blood

• The antistreptolysin O (ASO) titer is often elevated and the throat culture positive for group A β-hemolytic streptococci

• Serum IgA may be elevated

Treatment

• Supportive

• Nonsteroidal anti-inflammatory drugs may be useful for the arthritis

• Corticosteroid therapy may provide symptomatic relief for severe gastrointestinal or joint manifestations but does not alter skin or renal manifestations

• If culture for group A β-hemolytic streptococci is positive or if the ASO titer is elevated, a therapeutic course of penicillin is warranted

Outcome

Prognosis

• Generally good, although symptoms frequently (25–50%) recur over a period of several months

• Microscopic hematuria may persist for years in patients with renal manifestations

• Progressive kidney failure occurs in < 5%, with an overall fatality rate of 3%

Reference