II. Epidemiology
-
Incidence
- Children: 3 to 26 (mean 14) in 100,000
- Adults: 0.8 to 1.8 in 100,000
- Age
- Children aged 2-11 years represent 75-90% of cases
- HSP is the most common acute Vasculitis in children
- Peak Incidence at 5 year old
- Milder case occur in children under age 2 years
- Adults
- Affects middle aged adults (32 to 50 years old)
- Children aged 2-11 years represent 75-90% of cases
- Gender
- Occurs more often in boys (2:1)
- Timing
- Occurs most frequently in spring and winter in children (no seasonality in adults)
III. Pathophysiology
- Preceding illness is commonly present
- Upper Respiratory Infection precedes HSP in 60-75% cases
- Fever, gastrointestinal symptoms and Joint Pain may precede rash by 1-2 weeks
- Acute immune complex-mediated, small vessel Leukocytoclastic Vasculitis
- Autoantibodies against endothelial cells
- IgA immune complexes form and deposit in skin, joints, Kidneys and Gastrointestinal Tract
- Results in localized inflammatory reactions with small vessel inflammation and necrosis
- Idiopathic inflammatory IgA Hypersensitivity
- Petechiae and Purpura
- IgA immune complexes deposit in small vessel walls of skin
- Gastrointestinal Hemorrhage
- IgA immune complexes deposit in small vessel walls of intestinal wall
- Crescentic Glomerulonephritis
- IgA immune complexes deposit in small vessel walls of renal mesangium
- Petechiae and Purpura
IV. Associated Conditions (preceding HSP)
-
Bacterial Infections
- Group A Streptococcus (most common - may be responsible for 30% of cases)
- Bartonella Henselae
- Campylobacter enteritis
- Salmonella
- Shigella
- Methicillin-Resistant Staphylococcus aureus (MRSA)
- Mycoplasma
- Haemophilus parainfluenza
- Helicobacter Pylori
- Viral Infections
-
Vaccinations
- Typhoid
- Measles
- Cholera
- Yellow Fever
- Medications (most common cause in adults; only an incomplete list of example drugs)
- Other Exposures
- Allergens in foods
- Cold exposure
- Insect Bites
V. Course
- Onset over days to weeks (following Upper Respiratory Infection in most cases)
- Duration: 4-6 weeks
- Symptoms may recurr in up to one third of patients (ultimately resolves within 4 to 6 months)
VI. Symptoms: Classic Triad (beyond rash, triad is not uniformly present)
- Palpable Purpura rash on lower extremities (gravity dependent regions)
- Abdominal Pain or renal involvement (Nephritis)
- Arthritis or Arthralgias
VII. Signs: Rash (100% of cases)
- Timing
- Rash is ultimately present in all cases, and precedes other HSP findings in most, but not all cases
- First appears as erythematous Papules
- Crops of palpable Purpura and Petechiae follow
- Purpura may enlarge to Ecchymoses, transition from purple to rust colored, and fade over 10 days
- Distribution
- Gravity and pressure dependent
- Typically appears on extensor surfaces of lower extremities, belt line and buttocks
- Can involve face and trunk
- Characteristics: Petechiae or palpable Purpura (primary lesion type)
- Characteristics: Other associated lesions
- Urticarial wheels
- Erythematous Macules
- Erythematous Papules
- Target lesions
- May appear similar to Erythema Multiforme
VIII. Signs: Abdominal Pain (60-80% of cases, especially in children)
- Diffuse, Colicky Abdominal Pain (may mimic Acute Abdomen) typically lasting <24 hours
- Abdominal Pain onset typically follows rash
- Stools may show occult or gross blood
- Hematuria
- Vomiting or Hematemesis (rarely severe) in up to 30% of patients
- Intussusception occurs in 2-5% of HSP cases
IX. Signs: Joint Involvement (70% of children; 25% of adults)
- Arthritis precedes rash in 25% of cases
- Transient Arthritis with no permanent deformity or damage
- Non-Migratory polyarthritis
X. Signs: Renal Disease (25-50% of cases)
-
General
- Most serious complication of HSP
- Risk Factors
- Age over 10 years old and adults
- Persistent Purpura
- Gastrointestinal Bleeding
- Severe Abdominal Pain
- Relapsing episodes
- Male gender
- Presentation
- Develops within 3 months of rash (typically within first month and rarely beyond 6 months)
- Hematuria is the most common presenting sign (most commonly asymptomatic Microscopic Hematuria)
- Red cell casts and Proteinuria may also be present
- Persistent Proteinuria increases risk of progressive Glomerulonephritis
- Risk of ESRD in 1% of patients over subsequent months
XI. Signs: Miscellaneous
- Most common associated findings in adults
XII. Complications (more common in adults)
- Most common complications
- Cardiopulmonary conditions
- Gastrointestinal conditions
- Intussusception (mural Hematoma is lead point) in 2-5% of cases
- Gastrointestinal Bleeding
- Bowel infarction
- Pancreatitis
- Gallbladder Hydrops
- Protein Losing Enteropathy
- Neurologic conditions
- Headaches
- Behavior Changes
- Seizures
- Mononeuropathy
- Intracranial Hemorrhage
- Renal disorders (2-20%)
- Hematuria
- Proteinuria (Nephrotic Syndrome may be present)
- Crescentic Glomerulonephritis (HSP Nephritis)
- Renal Failure (end-stage renal disease)
- Occurs in 1-7% of with NSP Nephritis
- Male genitourinary conditions (Testicular Pain in 30% of boys with IgA Vasculitis)
XIII. Differential Diagnosis (based on predominant presenting symptom)
-
Purpura
-
Hypersensitivity Vasculitis
- Elevated Renal Function tests (BUN, Creatinine)
- Global organ involvement
- Meningococcal Meningitis or Septicemia
- Idiopathic Thrombocytopenic Purpura
- Child Abuse
- Bacterial Endocarditis
- Rheumatic Fever
- Rocky Mountain Spotted Fever
- Drug Reactions
- Polyarteritis Nodosa
- Leukemia
- Kawasaki Disease
-
Hypersensitivity Vasculitis
- Arthritis
-
Abdominal Pain
- Acute Abdomen
- Familial Mediterranean Fever
- Inflammatory Bowel Disease
- Hemolytic-Uremic Syndrome
XIV. Diagnosis: EULAR/PReS Criteria
- Background
- Replaces ACR 1990 criteria
- Lab tests are not required to make diagnosis (i.e. Purpura AND Arthralgias or Abdominal Pain)
- Major criteria (required)
- Minor criteria (requires 1 of the following)
- Acute Arthritis or Arthralgia involving any joint
- Diffuse Acute Abdominal Pain
- Biopsy showing Leukocytoclastic Vasculitis or proliferative Glomerulonephritis with IgA deposition
- Renal involvement presenting as Proteinuria or Hematuria
- Efficacy
- Child: 100% Test Sensitivity and 87% Test Specificity
- Adult: 99% Test Sensitivity and 86% Test Specificity
- References
XV. Labs: Initial
- First-Line Testing
- Urinalysis: Nephritis evaluation (nephrology evaluation if positive)
- Most important lab in suspected HSP
- Hematuria or Proteinuria in up to 50% of patients
- RBC Casts may be present
- Streptococcus Testing
- Rapid Strep Test (Throat Cultures positive in 10-30% of cases)
- ASO Titer (increased in 20-50% of cases)
- Urinalysis: Nephritis evaluation (nephrology evaluation if positive)
- Second-Line Testing (if Urinalysis positive for Proteinuria)
- Renal Function tests (BUN, Creatinine)
- Obtain if positive urine for Hematuria or Proteinuria
- Elevation may suggest Hypersensitivity Vasculitis
- Complete Blood Count (CBC)
- Leukocytosis with Eosinophilia
- Platelets may be elevated
- Low Platelets suggest Thrombocytopenic Purpura
- Renal Function tests (BUN, Creatinine)
- Other labs to consider
- Acute phase reactants (e.g. CRP, ESR)
- Sedimentation rate (ESR) variably elevated
- Coagulation Studies (PTT and INR)
- Normal in HSP
- Consider in differential diagnosis for Purpura
- Stool Guaiac
- Occult or gross blood may be present
- Normal in HSP
- Blood Culture
- Bacteremia in differential diagnosis for Purpura
- Fecal Calprotectin
- Marker for gastrointestinal involvement
XVI. Labs: Histology
- Skin Biopsy (indicated in unclear diagnosis)
- Leukocytoclastic Vasculitis with IgA vascular deposits
- Renal Biopsy (indicated in progressive Glomerulonephritis)
- Proliferative Glomerulonephritis with predominant IgA Deposition
- Glomerular crescents
- Indistinguishable from IgA Nephropathy
XVII. Imaging
- Not routinely indicated
-
Abdominal Ultrasound
- Indicated in suspected Intussusception in Children
-
Abdominal CT
Abdomen
- Indicated for concurrent gastrointestinal symptoms suggestive of alternative diagnosis (esp. adults)
- Endoscopy
- May be indicated in gastrointestinal Hemorrhage
- Bronchoscopy
- Indicated in Pulmonary Hemorrhage
XVIII. Management: General
- Supportive care (Primary strategy)
- Hydration
- Relative rest
- Elevate legs (may reduce Purpura)
- Rash
- No specific management
-
Joint Pain
- Acetaminophen
-
NSAIDs (with caution and avoid in renal involvement)
- Risk of renal disease
- Risk of Gastrointestinal Bleeding
- Nephritis (Hematuria or Proteinuria)
- Mild to Moderate Disease
- Indications for conservative management with no treatment
- Hematuria alone
- Urine Protein to Creatinine Ratio <0.5
- Normotensive
- Normal eGFR
- Indications for consideration of ACE Inhibitor
- Urine Protein to Creatinine Ratio 0.5 to 1.5 persists >2 to 4 weeks
- Borderline Hypertension
- Corticosteroids are no longer recommended for children with mild to moderate renal involvement
- As of 2013-2015, Corticosteroids (and Cyclophosphamide) appear to have no benefit in non-severe disease
- Dudley (2013) Arch Dis Child 98(10): 756-63 [PubMed]
- Hahn (2015) Cochrane Database Syst Rev (8): CD005128 [PubMed]
- Indications for conservative management with no treatment
- Severe Disease
- Indications
- Management
- Children with mild to moderate renal disease
- Systemic Corticosteroids are no longer recommended (see below)
- Adults and children with moderate to severe disease
- High dose Corticosteroids
- Methylprednisolone IV for decreased eGFR or crescentic Glomerulonephritis
- Prednisone for 6 months if significant Proteinuria despite 3 months on ACE Inhibitor
- Immunosuppressants (e.g. Cyclosporine, Mycophenolate, Dapsone, Rituximab)
- High dose IV Ig
- Plasmapheresis
- High dose Corticosteroids
- Nephrology Consultation
- Consideration for Renal biopsy
- Children with mild to moderate renal disease
- Mild to Moderate Disease
XIX. Management: Systemic Corticosteroids
- Indications: Symptomatic management
- Children with severe extrarenal, refractory symptoms (e.g. Abdominal Pain, Joint Pain)
- Scrotal Swelling
- Dosing
- Prednisone 1 mg/kg (up to 2 mg/kg) orally daily for two weeks
XX. Management: Hospitalization Indications
- Severe Dehydration or unable to take oral fluids (e.g. Abdominal Pain, Vomiting)
- Intractable pain or Abdominal Pain requiring serial examination and observation
- Gastrointestinal Hemorrhage
- Inability to ambulate
XXI. Prognosis
- Excellent in general
- Resolves spontaneously in 94% of children
- Resolves spontaneously in 89% of adults
- However cases are more severe in adults with worse outcomes than with children
- Recurrence
- Relapse occurs in up to 30% of children, up to 50% of adults
- Relapse may be delayed as long as 10 years after prior episode
- Relapse is most common in adults with gastrointestinal symptoms
- Calvo-Rio (2016) Medicine 95(28):e4217 [PubMed]
- Renal Disease
- Up to 50% will have Hematuria or Proteinuria
- Longterm renal disease develops in 5% of cases overall
- Child: <1% develop End Stage Renal Disease
- Adult: Up to 11% develop End Stage Renal Disease
- Predictors of serious nephropathy or ESRD
- Early onset of renal findings
- Abnormal Urinalysis on the day of HSP diagnosis (children)
- Renal involvement occurs within 6 weeks in 91% and 6 months in 97%
- Low likelihood of chronic renal complications if no renal involvement by 6 months
- Nephritis at HSP diagnosis confers longterm Hypertension and urine abnormalities risks
- Nephrotic Syndrome at HSP diagnosis (lasting >3 months) confers longterm renal disease risk
- Bloody stools
- Rash persistence
- Renal Biopsy with glomerular crescents
- Progresses to ESRD in 100% of cases
- Early onset of renal findings
XXII. Monitoring
- Renal involvement screening
- Blood Pressure initially and at each subsequent visit following the HSP diagnosis
- Urinalysis in all patients at time of HSP diagnosis and periodic screening over subsequent 6 months
- Obtain monthly Urinalysis for 6 months if initial Urinalysis with Hematuria or Proteinuria
- If any Urinalysis suggests nephritis (Hematuria and Proteinuria)
- Cancer screening in adults with HSP over age 60 years
XXIII. References
- Mace (2021) Crit Dec Emerg Med 35(2): 12-3
- Sas (2024) Mayo Clinic Pediatric Days, attended lecture 1/16/2024
- Kraft (1998) Am Fam Physician 58(2): 405-408 [PubMed]
- Gedalia (2004) Curr Rheumatol Rep 6(3):195-202 [PubMed]
- Reamy (2009) Am Fam Physician 80(7): 697-704 [PubMed]
- Reamy (2020) Am Fam Physician 102(4): 229-33 [PubMed]
- Saulsbury (2007) Lancet 369(9566): 976-8 [PubMed]
- Saulsbury (2001) Curr Opin Rheumatol 13(1):35-40 [PubMed]