Definition, Diagnostic Criteria & Classification
| Question | Answer |
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| 1. Detail the 2010 EULAR/PRINTO/PRES consensus diagnostic criteria for IgA Vasculitis (Henoch-Schönlein Purpura). | The diagnosis is established by the presence of Palpable Purpura (mandatory criterion) with lower extremity predominance, in the absence of thrombocytopenia or coagulopathy, PLUS at least one of the following four criteria: 1) Diffuse Abdominal Pain: Acute onset, diffuse, colicky pain with history of bowel angina (may include intussusception or GI hemorrhage). 2) Histopathology: Leukocytoclastic vasculitis with predominant IgA deposition, or proliferative glomerulonephritis with predominant mesangial IgA deposition. 3) Arthritis or Arthralgia: Acute onset of arthritis (swelling, warmth, tenderness) or arthralgia in any joint. 4) Renal Involvement: - Proteinuria: $>0.3\text{ g/24 hours}$ or spot urine protein-to-creatinine ratio (UPCR) $>30\text{ mg/mmol}$ ($>0.2\text{ mg/mg}$), OR - Hematuria: $>5\text{ RBCs/HPF}$ or red blood cell casts. |
| 2. Describe the classical physical characteristics and distribution of the rash in IgA Vasculitis. | - Appearance: Begins as erythematous maculopapular or urticarial wheals that rapidly evolve into non-blanching palpable purpura and petechiae, occasionally with bullae or focal necrosis. - Distribution: Strikingly gravity-dependent and symmetrical, localized to the lower extremities (buttocks, extensor surfaces of thighs, legs) and lower abdomen. In non-ambulatory infants, it concentrates on the face, ears, and upper extremities. - Sparing: Trunk and abdomen above the umbilicus are characteristically spared. |
| 3. How is the joint involvement in IgA Vasculitis characterized? | - Present in $65-85\%$ of cases. - Nature: Acute, painful, non-deforming, periarticular swelling and arthralgia rather than true synovial effusions. - Distribution: Oligoarticular, predilection for large lower-extremity joints (ankles and knees). - Resolution: Transient and self-limiting; resolves completely within 1 to 2 weeks without any chronic joint destruction or deformities. |
| 4. What are the common gastrointestinal manifestations and complications of IgA Vasculitis? | - Present in $50-75\%$ of patients. - Pathology: Submucosal and intramural hemorrhage and edema within the bowel wall. - Symptoms: Colicky periumbilical abdominal pain, nausea, vomiting, hematochezia, or melena. - Complications: 1) Intussusception: Occurs in $1-5\%$ of patients. Hallmark: Typically ileo-ileal ($60-70\%$) rather than the conventional idiopathic ileo-colic form; lead point is an intramural hematoma. 2) Bowel infarction, intestinal perforation, acute appendicitis, and massive GI hemorrhage. |
| 5. VIVA TRAP: A 6-year-old child presents with typical purpura, severe abdominal pain, and arthritis, but the platelet count is 35,000/uL. Can this be Henoch-Schönlein Purpura? | NO! Thrombocytopenia is an ABSOLUTE EXCLUSION for classic IgA Vasculitis. By definition, the purpura of HSP is non-thrombocytopenic (platelet counts are normal or elevated as an acute-phase reactant). Palpable purpura in the presence of severe thrombocytopenia indicates an alternate diagnosis: Immune Thrombocytopenia (ITP), Meningococcemia, Thrombotic Thrombocytopenic Purpura (TTP), Hemolytic Uremic Syndrome (HUS), or acute leukemia! |
Pathophysiology & Complications
| Question | Answer |
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| 6. Explain the molecular pathogenesis of IgA Vasculitis. | - HSP is an immune-complex-mediated small vessel vasculitis. - The "Galactose-Deficient IgA1" (Gd-IgA1) Pathway: 1) Abnormal O-glycosylation of the hinge region of immunoglobulin A1 produces Gd-IgA1. 2) Exposure to mucosal antigens (upper respiratory tract infection, Streptococcus, Mycoplasma) triggers hyperproduction of Gd-IgA1. 3) Circulating autoantibodies (IgG and IgA) recognize terminal N-acetylgalactosamine on Gd-IgA1, forming circulating macromolecular IgA1-immune complexes. 4) Immune complexes deposit in small vessels (capillaries, venules, arterioles) of the skin, gastrointestinal tract, and renal mesangium. 5) Activates the alternative complement pathway and recruits neutrophils, releasing lysosomal enzymes and generating leukocytoclastic vasculitis (nuclear debris / leukocytoclasia). |
| 7. Detail the ISKDC (International Study of Kidney Disease in Children) histological grading of HSP Nephritis. | Based on renal biopsy findings: - Grade I: Minimal glomerular abnormalities. - Grade II: Pure mesangial proliferation (focal or diffuse) without crescents. - Grade III: Focal or diffuse mesangial proliferation with $<50\%$ cellular crescents (IIIa: focal; IIIb: diffuse). - Grade IV: Mesangial proliferation with $50\% \text{ to } 75\%$ crescents. - Grade V: Mesangial proliferation with $>75\%$ crescents. - Grade VI: Membranoproliferative-like lesions. |
| 8. What are the clinical risk factors for developing chronic progressive HSP Nephritis? | 1) Presentation with nephrotic-range proteinuria or combined nephritic-nephrotic syndrome. 2) Renal insufficiency (elevated creatinine) at presentation. 3) Age of onset $>8-10$ years. 4) Severe, persistent abdominal pain or GI bleeding. 5) Persistent purpura lasting $>1$ month or recurrent relapses. 6) Renal biopsy demonstrating $\ge 50\%$ crescents (ISKDC Grade IV/V). |
Guidelines & Management Protocols (PReS / SHARE Guidelines)
| Question | Answer |
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| 9. VIVA TRAP: Do systemic Corticosteroids prevent the onset of HSP Nephritis or reduce long-term renal damage? | NO, EMPHATICALLY NO. Multiple high-quality randomized controlled trials and Cochrane systematic reviews have conclusively proven that early prophylactic administration of corticosteroids does NOT prevent the development of nephritis, nor does it reduce the progression to chronic kidney disease at 6 or 12 months! Steroids are indicated ONLY for: - Severe colicky abdominal pain unresponsive to analgesics. - Significant gastrointestinal hemorrhage. - Symptomatic bowel edema / non-surgical intussusception. - Severe painful scrotal or soft tissue edema. - Pulmonary hemorrhage or central nervous system involvement. |
| 10. Detail the management protocol for HSP Nephritis based on severity. | 1) Mild Nephritis (Isolated microscopic hematuria, non-nephrotic proteinuria $<0.5-1.0\text{ g/24 hr}$): - ACE inhibitors or ARBs (Enalapril $0.1-0.5\text{ mg/kg/day}$) to reduce intraglomerular pressure and proteinuria; strict blood pressure control. 2) Moderate to Severe Nephritis (Nephrotic-range proteinuria $>1\text{ g/24 hr}$, nephritic syndrome, or ISKDC Grade III): - Oral Prednisolone: $2\text{ mg/kg/day}$ (max $60\text{ mg}$) for 4 weeks, then tapered over 3-6 months, PLUS ACEi. 3) Crescentic / Rapidly Progressive Glomerulonephritis (RPGN, ISKDC Grade IV/V): - IV Pulse Methylprednisolone: $30\text{ mg/kg/day}$ (max $1000\text{ mg}$) x 3 consecutive days. - Immunosuppression: IV Cyclophosphamide pulses ($500-750\text{ mg/m}^2$ monthly for 6 doses) OR oral Mycophenolate Mofetil (MMF $600-1200\text{ mg/m}^2/\text{day}$). |
| 11. Outline the mandatory outpatient renal surveillance protocol for a child with IgA Vasculitis. | Because $>85\%$ of renal involvement develops within the first 6 weeks, but late nephritis can manifest up to 6 months: - Schedule: Check Blood Pressure and First Morning Urine Analysis (protein and microscopic hematuria): - Weeks 1 to 4: Weekly. - Weeks 5 to 12: Every 2 weeks. - Months 4 to 6: Monthly. - If urinalysis remains completely normal at 6 months, discharge from routine surveillance. - If proteinuria or hematuria is detected at any point, quantify with urine protein-to-creatinine ratio (UPCR) and serum creatinine. |
VIVA TRAPs & Counter-Questions
| Question | Answer |
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| 12. VIVA TRAP: How do you differentiate Ileo-ileal Intussusception of HSP from classic Idiopathic Intussusception? | - Location: Classic idiopathic intussusception is almost always Ileo-colic ($>90\%$). HSP intussusception is predominantly Ileo-ileal ($60-70\%$) because vasculitic lesions concentrate in the small intestine. - Diagnosis: Abdominal ultrasound is the investigation of choice (target / doughnut sign in small bowel). - Management TRAP: Air or hydrostatic enema reduction is INEFFECTIVE and CONTRAINDICATED for ileo-ileal intussusception (enema does not reach the ileum and risks perforating vasculitic bowel)! Requires emergent open/laparoscopic surgical manual reduction or resection! |
| 13. Counter-Question Chain: "When is a Renal Biopsy indicated in Henoch-Schönlein Purpura?" | Renal biopsy is indicated in: 1) Severe nephrotic-range proteinuria ($UPCR > 2.0\text{ mg/mg}$ or $>2.5\text{ g/24 hr}$) persisting for $>4$ weeks. 2) Acute nephritic syndrome (hypertension, gross hematuria, oliguria, elevated creatinine). 3) Rapidly progressive glomerulonephritis (doubling of serum creatinine or declining eGFR). 4) Persistent moderate proteinuria ($UPCR > 0.5-1.0\text{ mg/mg}$) unresponsive to 3 months of ACE inhibitor therapy. |