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Henoch-schönlein Purpura

Discover the lesser-known condition of Henoch-Schönlein Purpura, its mysterious symptoms, and potential treatments in this eye-opening article.
2023-05-15

USMLE Guide: Henoch-Schönlein Purpura

Introduction

Henoch-Schönlein Purpura (HSP), also known as IgA vasculitis, is a systemic small vessel vasculitis that primarily affects children. This USMLE guide aims to provide a comprehensive overview of HSP, including its clinical presentation, pathophysiology, diagnosis, and management.

Clinical Presentation

  1. Skin Manifestations

    • The hallmark feature of HSP is palpable purpura, typically on the lower extremities and buttocks.
    • Purpura may be preceded by erythematous macules or papules.
    • It may also involve the upper extremities, face, and trunk.
    • Lesions are non-thrombocytopenic and do not blanch on pressure.
  2. Joint Involvement

    • Arthritis or arthralgia is present in the majority of cases.
    • Most commonly affects the knees and ankles.
    • Joint symptoms are migratory and self-limited.
  3. Gastrointestinal (GI) Symptoms

    • Abdominal pain is a common complaint.
    • May be associated with nausea, vomiting, or bloody stools.
    • Intussusception, although rare, can occur as a complication.
  4. Renal Involvement

    • Hematuria and proteinuria are common, often manifesting as tea-colored urine.
    • Renal involvement may range from mild to severe, including nephritis and nephrotic syndrome.

Pathophysiology

  1. Immunologic Mechanisms

    • HSP is thought to be an immune complex-mediated vasculitis.
    • Deposition of IgA immune complexes in small vessels triggers an inflammatory response.
    • Complement activation and neutrophil infiltration contribute to vascular damage.
  2. Precipitating Factors

    • HSP is often preceded by an upper respiratory tract infection or other viral illness.
    • Certain drugs, insect bites, and vaccinations have also been associated with HSP.
  3. Genetic Predisposition

    • HSP has a higher incidence in individuals with a family history of the disease.
    • Genetic factors may influence susceptibility to immune complex formation.

Diagnosis

  1. Clinical Evaluation

    • Diagnostic criteria include palpable purpura with at least one of the following:
      • Abdominal pain
      • Arthritis or arthralgia
      • Renal involvement (hematuria, proteinuria)
    • HSP should be considered in children with these findings.
  2. Laboratory Investigations

    • Urinalysis: Presence of hematuria and/or proteinuria.
    • Elevated acute phase reactants (e.g., ESR, CRP).
    • IgA levels may be elevated, but this is not specific for HSP.
  3. Renal Biopsy

    • Reserved for cases with severe renal involvement or atypical presentation.
    • Demonstrates mesangial IgA deposition and variable degrees of glomerular injury.

Management

  1. Supportive Care

    • Symptomatic treatment includes rest, hydration, and pain relief.
    • Joint symptoms can be managed with nonsteroidal anti-inflammatory drugs (NSAIDs).
    • Severe GI involvement may require nasogastric decompression or surgical intervention.
  2. Renal Involvement

    • Mild cases often resolve spontaneously, requiring close monitoring.
    • Severe nephritis or nephrotic syndrome may warrant corticosteroid therapy.
    • ACE inhibitors or angiotensin receptor blockers (ARBs) may be used for proteinuria.
  3. Complications

    • Intussusception: Requires immediate surgical consultation.
    • Renal involvement: Long-term follow-up for monitoring renal function and blood pressure.

Conclusion

Henoch-Schönlein Purpura is a self-limiting vasculitis primarily affecting children. Understanding its clinical presentation, pathophysiology, diagnosis, and management is essential for medical professionals. This USMLE guide provides a comprehensive overview to aid in the preparation for exams or clinical practice.

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