What are the typical findings on physical exam of leukocytoclastic vasculitis?

Physical Examination Findings in Leukocytoclastic Vasculitis

The hallmark physical examination finding in leukocytoclastic vasculitis (LCV) is palpable purpura, primarily affecting the lower extremities and buttocks. This characteristic presentation is essential for clinical diagnosis and should prompt further investigation 1, 2.

Key Physical Examination Findings

Cutaneous Manifestations

• Palpable purpura: The most common and distinctive finding
  • Typically symmetrically distributed
  • Predominantly affects dependent areas (lower extremities and buttocks)
  • May be painful or burning in nature
• Additional skin findings:
  • Maculopapular rash
  • Bullae (fluid-filled blisters)
  • Papules
  • Plaques
  • Nodules
  • Ulcers
  • Livedo reticularis (reticular, purple discoloration of the skin) 2

Distribution Pattern

• Lower extremities (most common)
• Buttocks
• Can extend to involve other areas including trunk and upper extremities
• Lesions often appear in crops and may coalesce

Timing and Evolution

• Lesions typically evolve over 1-2 weeks
• May start as erythematous macules that progress to palpable purpura
• Color changes from red to purple, then brown before resolving
• Post-inflammatory hyperpigmentation may persist after resolution

Associated Physical Findings

Systemic Involvement

When LCV is part of a systemic vasculitis, additional findings may include:

• Gastrointestinal: Abdominal tenderness (particularly in IgA vasculitis/Henoch-Schönlein purpura) 3
• Musculoskeletal: Joint swelling, tenderness, and warmth (arthritis) 3
• Genitourinary: Penile swelling and discoloration (rare presentation) 4
• Renal: Typically no specific findings on physical exam, but urinalysis may reveal hematuria or proteinuria 3

Diagnostic Approach

While palpable purpura is highly suggestive of LCV, confirmation requires:

1. Skin biopsy: The gold standard for diagnosis

   • Should be performed on a fresh lesion (<24-48 hours old)
   • Histopathology shows neutrophilic infiltration, leukocytoclasia (nuclear debris), and fibrinoid necrosis of vessel walls 1

2. Laboratory evaluation: To determine if LCV is isolated or part of systemic disease

   • Complete blood count
   • Renal function and urinalysis
   • Serological tests (hepatitis B/C, ANA, ANCA)
   • Complement levels
   • IgA levels (if IgA vasculitis suspected) 1

Clinical Pearls

• Palpable purpura that blanches with pressure may indicate an early lesion
• Non-blanching purpura suggests established vasculitis with extravasation of red blood cells
• Distribution pattern helps distinguish LCV from other causes of purpura (thrombocytopenia typically causes non-palpable purpura)
• The presence of systemic symptoms should prompt evaluation for underlying systemic vasculitis or secondary causes

Common Pitfalls

• Mistaking non-palpable purpura (as seen in thrombocytopenia) for LCV
• Failing to perform a skin biopsy on a fresh lesion
• Not evaluating for systemic involvement or underlying causes
• Overlooking medication-induced LCV, which requires prompt discontinuation of the offending agent 5

By recognizing the characteristic palpable purpura and associated findings, clinicians can promptly diagnose LCV and initiate appropriate evaluation for underlying causes and systemic involvement.