What are the causes and treatments of purpuric dermatosis?

Treatment of Purpuric Dermatosis: Causes and Management

Purpuric dermatosis should be treated with narrowband UVB phototherapy as first-line therapy, with PUVA considered if narrowband UVB fails, and oral rutoside plus ascorbic acid as an effective alternative treatment option, especially in early disease. 1, 2, 3

Causes of Purpuric Dermatosis

Pigmented purpuric dermatoses (PPD) are a group of chronic disorders characterized by petechiae with tiny red rashes and brown pigmented patches, most commonly located on the lower extremities. The causes include:

• Possible microbial factors - recent evidence suggests oral bacteria may be a causative factor in some cases 4
• Vascular inflammation - histopathologically similar to vasculitis but without true vasculitis 5
• Chronic nature - can persist for years (up to 20 years in documented cases) without proper treatment 4

Treatment Algorithm

First-Line Therapy:

• Narrowband UVB phototherapy
  • Recommended schedule: three times weekly until clearance 1
  • Maintenance: twice weekly for 3 weeks, then once weekly for 3 weeks 1
  • Complete clearance can be achieved after 24-28 treatments plus maintenance 1
  • Preferred over PUVA due to better safety profile (similar to recommendations for other dermatoses) 6

Second-Line Therapy:

• PUVA (Psoralen plus UVA) therapy
  • Consider if narrowband UVB has not been adequately effective 6, 3
  • Similar to guidelines for other dermatoses where PUVA is typically reserved for cases resistant to narrowband UVB 6
  • Has shown successful response in documented cases 3

Alternative Effective Treatment:

• Antioxidant therapy with rutoside and ascorbic acid
  • Dosage: 2 × 50 mg rutoside and 1,000 mg ascorbic acid daily 2
  • Highly effective: 71.4% complete clearance and 20% improvement of more than 50% 2
  • Better outcomes with earlier treatment initiation 2
  • Average treatment duration: 8.2 months 2
  • Well-tolerated with minimal side effects 2

Important Clinical Considerations

• Early treatment is crucial - patients with shorter disease duration show better therapeutic success, shorter time to response, and lower risk of recurrence 2

• Relapse management:

  • About 25% of patients may relapse after treatment discontinuation 2
  • Re-initiation of previously effective therapy typically results in good response 2
  • For UVB treatment failures, additional 14 treatments can effectively control flares 1

• Treatment monitoring:

  • Follow patients for at least one year after treatment 1
  • Residual pigmentation may require additional interventions such as vitamin C administration or laser treatment 4

• Special considerations for phototherapy:

  • Similar precautions as with other dermatoses treated with phototherapy 6
  • Side effects may include erythema and pruritus, which are generally manageable 6

Pitfalls and Caveats

• Pigmented purpuric dermatosis is often misdiagnosed as vasculitis or bleeding disorder, leading to inappropriate treatment 2
• No standardized treatments exist due to limited understanding of pathogenic mechanisms and rarity of the condition 5
• Most treatment evidence comes from case reports or small series, limiting strong recommendations 5
• Chronic nature of the disease means long-term management strategies may be necessary 4