psoriasis
PSORIASIS

Psoriasis is a systemic chronic skin disorder characterized by excessive keratinocytes proliferation that results into thickened scaly plaques, itching and inflammatory changes in the epidermis and dermis. It is transmitted genetically but can be provoked by environmental factors.
It is found in approximately 2% of the population that primarily affects the skin and joints.
It is associated with other inflammatory disorders and autoimmune diseases (eg psoriatic arthritis, inflammatory bowel disease, coronary artery disease).
Generally, it begins as red scaling papules that coalesce to form round-to-oval plaques. The rashes are often pruritic and may be painful.

Supportive Therapy

Phototherapy/Photochemotherapy

  • Phototherapy is generally used in patients with moderate-severe psoriasis, with psoriasis in vulnerable areas that is unresponsive to topical therapy or other mitigating symptoms are present
  • Review patient’s medical history and review systems to verify that patient does not have photosensitive diseases or medications (eg history of ionizing radiation)
  • Lubricants and emollients are needed for the efficacy of phototherapy
  • If possible, sunblock should be applied to unaffected skin
  • Protect breast, ocular and genital areas during phototherapy sessions
  • Safe and efficacious without the potent adverse effects of systemic and immunosuppressive therapies

Broadband Ultraviolet B (BB UVB)

  • Typically used in failed topical treatment, chronic stable plaque psoriasis or guttate psoriasis
  • Safe, effective and cost-effective
  • Most effective spectrum of UVB phototherapy in psoriasis is 300-313 nm
  • Average of 20-25 treatments to induce clearance, given 3-5 days/week
  • Clear emollients (eg petrolatum or mineral oil), improve the optical properties of the skin and should be applied prior to UVB treatment
  • UVB + topical or systemic treatments can achieve results that are more effective and have a faster onset
  • May be combined with topical vitamin D analogues (after UV exposure), topical coal tar, Psoralen + Ultraviolet A (PUVA), topical retinoid, low cumulative dose of systemic Methotrexate, or low dose of oral retinoids
  • Adverse reactions:
    • Short-term: Erythema, itching, burning, stinging
    • Long-term: Photoaging, dermatoheliosis

Narrow Band Ultraviolet B (NB UVB)

  • Consists of utilizing UV light spectrum around 311 nm
  • Recommended for patients with >50% baseline disease severity 3 months after treatment and in patients at high risk for skin cancer
  • Useful in patients with localized plaque or guttate psoriasis refractory to topical treatments and broadband UVB
  • Superior to broadband UVB but not as effective as PUVA
    • Burns may be more severe and longer-lasting as compared to broadband UVB treatment
    • Appears to be safer than PUVA 
  • Average of 15-30 treatments to induce clearance, given 2-3 times/week; more effective than broadband UVB with clearance within 2 weeks of treatment
  • Adverse reactions:
    • Short-term: Burning
    • Long-term: Skin cancer

Psoralen plus UVA (PUVA)

  • Highly effective in the treatment of moderate-severe plaque, guttate pattern psoriasis that cannot be controlled by topical therapy and with potential for long remissions
  • Up to 90% of patients achieve improvement or clearing of plaques after 20-30 treatments, given 2-3x/week
  • Psoralen is usually taken orally 90-120 minutes prior to administration of UV
  • Patients must wear protective eye gear and sunscreens must be used throughout the day due to photosensitizing effect of psoralens
  • Adverse reactions:
    • Short-term: Eerythema, irregular pigmentation, xerosis, pruritus, N/V
    • Long-term: Cutaneous malignancies (eg squamous cell carcinoma and possible melanoma) which are usually dependent on the cumulative dose, increased risk of photo damage, lentigines
    • Lifetime exposure should be limited to 200 PUVA sessions to minimize the risk of cancers 
  • Combinations: PUVA + topical or systemic treatments can achieve results that are more effective and have a faster onset
  • May be combined with low dose of oral retinoids, systemic Methotrexate (only for very severe psoriasis), vitamin D analogues, topical retinoid, topical steroids, or UVB

Soak/Bath PUVA

  • Used in patients with localized palmoplantar pustulosis prior to UVA exposure
  • May be alternative in patients with generalized psoriasis who cannot tolerate oral psoralens

308-nm Excimer Laser

  • Initial studies show that excimer laser is well-tolerated and effective in treating localized mild to moderate plaque psoriasis involving <10% BSA
  • May also be used in patients with <10% BSA involvement
  • Specifically targets the affected skin and spares the uninvolved skin using a reduced cumulative dose thereby decreasing the long-term risk of malignancy
  • Average of 10-12 treatments are needed to induce clearance, given 2-3x/week
  • Patients may be in remission for up to 2 years
  • Common side effects with lower doses are erythema and hyperpigmentation while erosions, blistering, and crusting may occur with higher doses
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