What is the treatment approach for palpable vs non-palpable purpura?

Treatment Approach for Palpable vs Non-Palpable Purpura

The treatment of purpura should be directed by the underlying cause, with palpable purpura typically requiring immunosuppressive therapy while non-palpable purpura often needs only supportive care. 1

Distinguishing Features

Palpable Purpura

• Raised, palpable lesions
• Usually indicates small vessel vasculitis
• Often associated with systemic symptoms
• Common causes:
  • Leukocytoclastic vasculitis
  • Henoch-Schönlein purpura (IgA vasculitis)
  • ANCA-associated vasculitis
  • Drug-induced vasculitis
  • Infection-related vasculitis

Non-Palpable Purpura

• Flat, non-raised lesions
• Usually indicates non-inflammatory causes
• Common causes:
  • Thrombocytopenia (ITP, drug-induced)
  • Coagulation disorders
  • Platelet dysfunction
  • Vascular fragility
  • Pressure/gravitational purpura

Diagnostic Approach

• Skin biopsy: Essential for palpable purpura to confirm vasculitis and identify type
• Direct immunofluorescence: Helps distinguish IgA-associated vasculitis from IgG/IgM-associated vasculitis 2
• Laboratory tests: CBC, coagulation studies, ANCA, complement levels

Treatment Algorithm for Palpable Purpura

1. Mild to moderate cutaneous vasculitis without systemic involvement:

   • Identify and remove triggers (drugs, infections) 2
   • NSAIDs for symptomatic relief
   • Colchicine or dapsone for persistent or recurrent disease 2

2. Moderate to severe cutaneous vasculitis:

   • Systemic corticosteroids: Prednisone 1-2 mg/kg/day for 2 weeks followed by taper 3
   • For IgA vasculitis (Henoch-Schönlein purpura) with severe abdominal pain unresponsive to conventional therapy, consider high-dose methylprednisolone pulse therapy (30 mg/kg/day, maximum 1g/day) 4

3. Severe vasculitis with systemic involvement:

   • High-dose corticosteroids (methylprednisolone 1-2 mg/kg IV) 1
   • Add immunosuppressants (cyclophosphamide, azathioprine, methotrexate) for refractory cases 2
   • For ANCA-associated vasculitis, combination of corticosteroids and cyclophosphamide is required 2

4. Refractory cases:

   • Consider plasmapheresis or intravenous immunoglobulin 2
   • Biologic therapies (rituximab, TNF-alpha inhibitors) for specific indications 2

Treatment Algorithm for Non-Palpable Purpura

1. Thrombocytopenic purpura (ITP):

   • If platelet count <30,000 or significant bleeding:
     • Prednisone 1-2 mg/kg/day 1, 5
     • Alternative: Dexamethasone 40 mg daily for 4 days 5
   • For severe, life-threatening bleeding:
     • IVIg 1 g/kg as one-time dose 1, 5
     • High-dose parenteral glucocorticoids 1
   • For refractory cases:
     • Splenectomy for patients who fail corticosteroid therapy 5
     • Thrombopoietin receptor agonists for patients who relapse after splenectomy 5

2. Non-thrombocytopenic, non-inflammatory purpura:

   • Supportive care
   • Treat underlying condition
   • Avoid precipitating factors (prolonged standing, pressure)

Special Considerations

1. Drug-induced purpura:

   • Immediate discontinuation of offending agent 6
   • For severe reactions (e.g., NSAID-induced IgA vasculitis with purpura fulminans), consider plasma exchange with fresh frozen plasma and immunosuppression 6

2. Pregnancy-associated purpura:

   • For ITP in pregnancy: Corticosteroids or IVIg 5
   • Delivery method based on obstetric indications, not platelet count alone 5

3. Purpura in immunotherapy patients:

   • For grade 3 rash (>30% BSA): Withhold immune checkpoint inhibitors, use topical treatments and systemic steroids (0.5-1 mg/kg prednisolone) 1
   • For grade 4 skin reactions: IV methylprednisolone 1-2 mg/kg, discontinue immunotherapy, urgent dermatology consultation 1

Common Pitfalls and Caveats

1. Misdiagnosing vasculitic purpura as simple thrombocytopenic purpura can lead to inadequate treatment and progression of systemic disease.

2. Failing to identify drug-induced purpura can lead to continued exposure and worsening symptoms.

3. Delaying treatment of severe vasculitis can lead to permanent organ damage, especially in ANCA-associated conditions.

4. Overtreatment of mild, self-limited purpura with potent immunosuppressants increases risk of adverse effects without benefit.

5. Not considering purpura fulminans in rapidly progressive purpuric rashes can lead to delayed treatment and increased morbidity 6.

By following this algorithmic approach based on the distinction between palpable and non-palpable purpura, clinicians can provide appropriate treatment while avoiding unnecessary interventions.