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Fototerapia

História
  • The therapeutic effect of ultraviolet (UV) rays was recognized in 1903 when Niels Finsen was awarded the Nobel Prize in Medicine for treating lupus vulgaris with a carbon arc lamp
  • 1925 Goeckerman → broad spectrum UVB
    • 1953 Ingram → used in combination with tar
  • 1974 Parrish and Fitzpatrick PUVA in psoriasis
  • 1990s - narrow band UVB ~311nm
  • 1990s germans UVA1 (340-400nm)
 
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Radiação UV
 
Mecanismo de ação da fototerapia
  • Antiproliferative effect
    • Due to direct DNA damage and oxidative stress (mainly PUVA)
  • Apoptotic effect
    • Contributes to photoimmunomodulation
    • Explains efficacy in cutaneous lymphomas and mastocytosis
  • Immunomodulatory effect
    • UV stimulate innate immunity and inhibit adaptive immunity
    • Functional inhibition of antigen-presenting dendritic cells, Th1 lymphocytes, TH17 lymphocytes, regulatory T cells, inihibition of inflammatory cytokine production
    • This explains efficacy in atopic dermatitis, vitiligo, photodermatosis, alopecia areata, lichen planus, GVHD, psoriasis
  • Effect on enzymatic activities
    • Production of collagenases by fibroblasts → action in scleroderma
  • Pigmentogenic effect
    • Contribute to the therapeutic action in vitiligo or photodermatoses (increase natural photoprotection)
  • The erythematogenic and mutagenic effects are, of course, undesirable
 
PUVA
  • Efeito mais forte que UVB
  • Penetra mais fundo na pele que UVB
  • Risco cancerígeno
  • Psoralens
    • Are isomers of the furocoumarin family
    • There are 2 classes:
      • Linear structure: 8-methoxypsoralen (8-MOP), 5-methoxypsoralen (5-MOP)
      • Angular structure: iso-psoralen, angelicin
    • 2 main types of photochemical reactions
      • Photoadditions with DNA - formation of a biadduct that bridges two strands of DNA inhibiting DNA synthesis
      • Photodynamic reationcs: production of reactive oxigen species creating high oxidative stress
    • Administration os psoralens
      • Oral: 0,6mg/kg body weight → followed 2 hours later by exposure to UVA
        • BUT → absortion kynetics differ between individuals
      • Topical: with a brush → irradiation 30-60min later
      • Balneo-PUVA
        • Mãos e pés são imersos numa solução aquosa de 8-methoxypsoralen at concentration of 2,5-4,6mg/L of water for 15 minutes at 35ºC
        • Also possible to immerse a limb or entire body
        • Immersion is immediately followed, after drying, by PUVA therapy (within a maximum of 10 minutes=
        • 2-3 sessions per week
 
Narrow band UVB 311 nm
  • Dose
    • Dose iniciar é mais ao menos o fototipo ex 0,3J/cm2 numa pessoa fototipo 3
    • Estimate to ~70% da Minimal erythrogenic dose
 
UVA1
  • Penetra mais fundo na derme
  • Indicações: morfeia
  • Dose
    • Low dose: 10J/cm2
    • Medium doses: 50J/cm2
    • High doses 130J/cm2
 
Indicações para fototerapia
  • Psoríase: nbUVB → PUVA se não responder
    • Plaque and guttate psoriasis → good response
    • Pustular psoriasis and erythrodermic psoriasis → contraindications
    • rePUVA → more effective. When phototherapy is stopped, acitretin may be continued
    • Combination of coal tar and UVB (Goeckerman technique)
  • Mycoses fungoides: PUVA, nbUVB
  • Atopic dermatitis: UVB with or without UVA combination, UVA1 for acute flare ups
  • Idiopathic photodermatoses
    • lucitis, polymorphic lucitis: nbUVB→ PUVA
    • solar urticaria: PUVA
    • chronic actinic dermatitis: PUVA combined with systemic corticosteroid therapy
  • Vitiligo: UVB superior to PUVA
    • One of the indications for targeted phototherapy (could complement UVB)
  • Lichen planus: PUVA, nbUVB
  • Mastocytosis: UVA1 spectacular
  • Alopecia areata: PUVA combined with systemic corticosteroids
  • Scleroderma: PUVA, UVA1
  • Chronic palmoplantar dermatoses: PUVA best
  • Pruritus (chronic renal failure, polycythemia, aquagenic pruritus, nodular prurigo): nbUVB
  • GVHD
  • Disseminated granuloma annulare
  • Lichenoid pityriasis
  • PRG
  • Digitiform parapsoriasis
 
Efeitos secundários
  • Early
    • “Sunburn”
    • Nause (psoralens)
    • Phototoxic and photoallergic reactions
    • Induction of dermatoses: flare-up of acne, rosacea, herpes, triggering seborrheic dermatitis in psoriasis patients, and in rare cases, autoimmune bullous dermatoses
    • Pregnancy
      • UVB safe
      • PUVA: stop
  • Late
    • Photoaging (PUVA)
      • PUVA induced lentigenes
    • Increased risk of skin cancer with PUVA
      • Increased risk for SCC
      • Lower risk for BCC
      • Low, late and limited risk for melanoma
      • UVB → no increased risk of cancer
    • Eye cataracts → use eye protection measures
 
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Considerar
  • Time required to travel may disrupt school or work
  • Home UV unit?