Henoch-Schönlein Purpura

Henoch-Schönlein purpura (HSP) is the most common systemic vasculitis in children and is thought to occur in 10 to 20 per 100,000 children.
Incidence is highest among children of Asian descent.
Mean age at onset is 4 to 6 years and it is more common in males, primarily in the fall and winter.

HSP is a systemic immune-mediated small vessel vasculitis characterized by IgA deposition within affected organs.
The underlying cause remains unknown but suspected etiologic agents include infections (viral or Group A streptococcus), vaccinations, or insect bites.

Signs and symptoms develop over the course of days to weeks and vary in order of presentation.
Typically, the skin eruption is the first sign followed by arthralgia/arthritis, abdominal pain or GI bleeding, and renal involvement.
Early skin lesions may be pink urticarial papules that evolve into deep red to purple nonblanching macules or petechiae.
The characteristic finding is palpable purpura, which is the result of swelling and extravasation of red blood cells.
Lesions are nonblanching meaning that they do not disappear when pressure is exerted on them.
Skin lesions are more common on dependent areas of the body including the legs and buttocks. The lateral malleolus is almost invariably involved (Fig. 10.1).
Lesions can vary in size and coalesce. Occasionally, vesicles, bullous lesions, and/or ulcers occur (Fig. 10.2).
If the scrotal vessels are affected, there may be acute scrotal swelling with or without erythema or purpura and is associated with severe pain.
Systemic involvement is common and occurs in 80% of affected children, most often in the GI tract and presents with colicky abdominal pain with or without vomiting.
The joints are the second most common site of systemic involvement.
Rarely, seizures, headaches, or intracerebral bleeding occurs.

The diagnosis of HSP is made clinically by and requires the presence of palpable purpura on the skin in addition to at least one of the following findings:
- Diffuse abdominal pain
- ANY biopsy showing predominant IgA deposition
- Arthritis or arthralgia
- Renal involvement
For atypical presentations, a skin biopsy with direct immunofluorescence showing leukocytoclastic vasculitis and IgA deposition can help solidify the diagnosis.

Differential Diagnosis

Hypersensitivity Vasculitis (i.e., Secondary to a Drug, etc.)

Management

Most patients with HSP recover fully without sequelae in 4 to 6 weeks.
Supportive care with oral hydration, bed rest, elevation of swollen areas is often sufficient.
Pain can be managed with acetaminophen or NSAIDs.
Skin lesions fade over 5 to 7 days with postinflammatory hyperpigmentation.
Hospitalization is warranted if patient is unable to maintain adequate hydration or if there is severe abdominal or joint pain, significant GI bleeding, or renal insufficiency.
Patients with kidney involvement require long-term follow-up.
Occasionally, patients may have recurrent flares of HSP.

Helpful Hints

Systemic steroids are reserved for cases of HSP with severe abdominal or joint pain.
In pediatric patients, biopsy is only necessary for patients with an unusual presentation of HSP (i.e., no rash, or an atypical rash) or those with significant renal disease.

Point to Remember

In mild cases of HSP, the lateral malleolus may be one of the few areas where the skin eruption is present.