Henoch-Schönlein Purpura

Basics

Increasingly referred to as immunoglobulin-A vasculitis (IgAV)

Description

  • Henoch-Schönlein purpura (HSP) is a nonthrombocytopenic, predominantly IgA-mediated, small vessel vasculitis that affects multiple organ systems and occurs in both children and adults.
  • HSP is often self-limited, with the greatest morbidity and mortality attributable to long-term renal damage.
  • Characterized by a tetrad of purpuric skin lesions, arthralgia, abdominal pain, and nephropathies

Epidemiology

Incidence

  • Annual incidence: estimated 29.9/100,000 children and 0.1 to 1.8/100,000 adults
  • Peak incidence: age 4 to 6 years; 90% of patients with HSP are <10 years of age; however, has been reported in patients aged 6 months to 75 years old
  • Gender: Male-to-female ratio is between 1.2:1 and 1.8:1.
  • Race/ethnicity: most common in Caucasians and Asians; less common among African Americans

Prevalence
Annual prevalence: 10 to 22/100,000 persons; more common in fall and winter

Etiology and Pathophysiology

  • Autoimmune disorder in which IgA production is increased in response to trigger(s), IgA1 immune complexes then activate the complement pathway, leading to production of inflammatory cytokines and chemokines.
  • IgA-containing immune complex deposition results in small vessel inflammation which leads to fibrosis and necrosis within skin, intestinal mucosa, joints, and kidneys.
  • No single etiologic agent has been identified; however, there are some associations (listed below) and a popular theory is one of a multihit model leading to HSP-associated glomerulonephropathy.
    • Infections are suggested by prevalence in the fall/winter and a common upper respiratory infection (URI) prodrome. Associated pathogens include (but are not limited to) group A Streptococcus (may be present in up to 30% of HSP-associated nephritis), parvovirus B19, Bartonella henselae, Helicobacter pylori, Haemophilus parainfluenzae, coxsackievirus, adenovirus, hepatitis A and B viruses, Mycoplasma, Epstein-Barr virus, herpes simplex, varicella, Campylobacter, and methicillin-resistant Staphylococcus aureus.
    • Drugs are most often associated with adults with HSP: acetaminophen, angiotensin-converting enzyme inhibitors (ACEI), angiotensin II receptor antagonists (ARB), some antibiotics including clarithromycin quinolones, etanercept, codeine, nonsteroidal anti-inflammatory drugs.
    • Vaccinations are rarely associated with HSP; MMR, pneumococcal, meningococcal, influenza and hepatitis B

Genetics
Associated with α1-antitrypsin deficiency, familial Mediterranean fever, HLA-A2, HLA-A11, HLA-B35, HLA-DRB1, renin-angiotensin, and nitric oxide synthetase polymorphisms

Commonly Associated Conditions

  • Rare association is with solid tumors, lymphoma, prostate cancer, non–small cell lung cancer, multiple myeloma.
  • Possible relationship with H. pylori infection and immune-related disorders (food allergy, drug allergy, inflammatory bowel disease)

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