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Henoch-Schönlein Purpura (HSP) or IgA Vasculitis
Henoch-Schönlein purpura (HSP), also known as Ig-A vasculitis, is a systemic small-vessel vasculitis characterized by the deposition of IgA-containing immune complexes in the vessel walls. It is the most common childhood vasculitis, accounting for approximately 90% of cases occurring in children aged 2 to 11 years. Despite its self-limiting nature in most cases, HSP can lead to significant morbidity and potential long-term complications, making it essential for healthcare professionals to have a comprehensive understanding of its clinical manifestations, diagnostic criteria, and management strategies.
Pathogenesis
The exact etiology of HSP remains unclear, but it is believed to involve an abnormal immune response triggered by various factors, such as infections (particularly upper respiratory tract infections), medications, or environmental exposures. The resulting formation of IgA-containing immune complexes and their deposition in small blood vessels lead to inflammation and subsequent vasculitic manifestations.
Clinical Manifestations
The clinical presentation of HSP is characterized by the classic tetrad of symptoms:
1. Palpable purpura
Non-blanching, raised, and often symmetrically distributed reddish-purple skin lesions, predominantly involving the lower extremities and buttocks, but can also involve the trunk and upper extremities.
2. Arthralgia or arthritis
Joint pain or swelling, most commonly affecting the knees, ankles, and elbows.
3. Abdominal pain
Caused by vasculitis involving the gastrointestinal tract, leading to colicky abdominal pain, nausea, vomiting, or gastrointestinal bleeding.
4. Renal involvement
Ranging from mild proteinuria and hematuria to severe nephritis, which can progress to chronic kidney disease in rare cases.
Other less common manifestations include testicular pain, headaches, and neurological symptoms.
Diagnostic Criteria
The American College of Rheumatology (ACR) established diagnostic criteria for HSP in 1990, which include:
1. Palpable purpura.
2. Age of onset below 20 years.
3. Abdominal pain, such as intestinal colic or gastrointestinal bleeding.
4. Histological evidence of granulocytic infiltration of arterioles or venules.
Meeting at least two of these four criteria has a sensitivity and specificity of approximately 90% for diagnosing HSP in adults.
Laboratory Findings
Laboratory tests are not specific for HSP but can aid in ruling out other conditions and assessing disease severity. Findings may include:
Elevated inflammatory markers, such as ESR and CRP.
Proteinuria or hematuria, indicating renal involvement.
Elevated serum IgA levels in some cases.
Normal platelet count and coagulation studies.
Treatment
HSP is a self-limiting condition in most cases, and treatment is primarily supportive, focusing on alleviating symptoms and preventing complications.
Supportive care
Adequate hydration, rest, and pain management with acetaminophen or NSAIDs.
NSAIDs are contraindicated in cases of gastrointestinal bleeding or renal involvement.
Corticosteroids: Although controversial, corticosteroids may be considered in severe cases with significant gastrointestinal, renal, or other organ involvement to reduce inflammation and prevent complications.
Immunosuppressive agents
In cases of severe or rapidly progressive nephritis, immunosuppressive agents such as cyclophosphamide or rituximab may be used in conjunction with corticosteroids.
Hospitalization: Indicated for severe abdominal pain, significant gastrointestinal bleeding, dehydration, altered mental status, or renal impairment.
Prognosis and Recurrence
The prognosis for HSP is generally favorable, with most cases resolving within 4 to 6 weeks without long-term complications.
However, renal involvement can lead to chronic kidney disease in a small percentage of cases, particularly in adults.
Recurrence is not uncommon, occurring in approximately one-third of cases, usually within the first four months after the initial episode. Factors associated with an increased risk of recurrence include renal involvement, elevated inflammatory markers, and steroid use during the initial episode.
In conclusion, Henoch-Schönlein purpura is a systemic small-vessel vasculitis that primarily affects children and is characterized by the classic tetrad of palpable purpura, arthritis or arthralgia, abdominal pain, and renal involvement. While self-limiting in most cases, prompt recognition and appropriate management are crucial to prevent potential complications, particularly renal involvement.