What is the typical clinical presentation of Henoch‑Schönlein purpura in a 7‑year‑old child?

Clinical Presentation of Henoch-Schönlein Purpura in a 7-Year-Old Child

A 7-year-old with HSP will present with palpable purpura on the lower extremities and buttocks, plus at least one of the following: arthralgia/arthritis (typically ankles and knees), colicky abdominal pain, or renal involvement with hematuria and/or proteinuria. 1

Classic Tetrad of Findings

The diagnosis is clinical and based on recognizing the characteristic pattern:

• Palpable purpura (100% of cases): Non-blanching, raised purpuric lesions predominantly on the lower extremities and buttocks, often extending to the extensor surfaces of arms 1, 2, 3
• Arthralgia or arthritis (common): Typically affects ankles and knees with periarticular swelling and pain 2, 4
• Abdominal pain (common): Colicky, cramping pain that may be severe; can present with nausea, vomiting, or gastrointestinal bleeding 2, 4
• Renal involvement (variable): Hematuria with or without proteinuria, red blood cell casts, and dysmorphic red blood cells indicating glomerulonephritis 1, 4

Age-Specific Presentation Features

At 7 years old, the presentation differs from younger children:

• Facial involvement is uncommon at this age, whereas infants under 2 years frequently present with facial purpura and prominent edema 5
• Renal and gastrointestinal involvement is more common in school-age children compared to infants, who typically have milder disease limited to skin and edema 5
• Joint involvement is more prominent in older children compared to infants 5

Dermatologic Findings

The rash evolves in a characteristic pattern:

• Begins as erythematous macules or urticarial lesions that progress to palpable purpura within 24 hours 2, 4
• Distribution is symmetric and gravity-dependent, favoring lower extremities and buttocks 2, 3
• Bullous lesions are rare but can occur as a presenting feature in some cases 3
• Lesions may appear in crops over several weeks 2

Renal Manifestations

Renal involvement occurs in 20-100% of cases depending on the series:

• Urinalysis is essential at every visit to detect hematuria, proteinuria, red blood cell casts, and dysmorphic red blood cells 1
• Most renal manifestations are mild and transient, though 2% of children progress to renal failure 4
• The majority of nephritis manifests within 3 months after initial presentation, requiring at least 6 months of monitoring 1
• Hypertension may indicate more severe renal involvement 1

Gastrointestinal Findings

Abdominal symptoms can be severe and occasionally precede the rash:

• Colicky abdominal pain, often periumbilical 2, 4
• Nausea, vomiting, and gastrointestinal bleeding 4
• Rarely, intussusception or bowel perforation can occur 4

Laboratory and Diagnostic Workup

The diagnosis is clinical, but specific tests are needed:

• Urinalysis with microscopy at presentation and every follow-up visit to assess for glomerulonephritis 1
• Basic metabolic panel including BUN and creatinine to assess renal function 1
• Complete blood count with platelets to rule out thrombocytopenia (platelets are normal in HSP) 1
• Blood pressure measurement to detect hypertension 1

Common Pitfalls

• Do not delay diagnosis waiting for all four classic features to appear; palpable purpura plus any one other feature is sufficient 1
• Do not assume absence of symptoms means no renal involvement; asymptomatic hematuria and proteinuria are common and require urinalysis for detection 1
• Do not use prophylactic corticosteroids at disease onset to prevent nephritis, as moderate-quality evidence shows no benefit 1

Prognosis at This Age

• School-age children typically have complete resolution, though renal involvement requires prolonged monitoring 2, 5
• Prognosis is excellent in children compared to adults, who have worse outcomes and higher risk of progression to end-stage renal disease 1, 4