Guidelines of care for the management of psoriasis and psoriatic arthritis

Psoriasis is a common, chronic, inflammatory, multisystem disease with predominantly skin and joint manifestations affecting approximately 2% of the population. In this fifth of 6 sections of the guidelines of care for psoriasis, we discuss the use of ultraviolet (UV) light therapy for the treatment of patients with psoriasis. Treatment should be tailored to meet individual patients' needs. We will discuss in detail the efficacy and safety as well as offer recommendations for the use of phototherapy, including narrowband and broadband UVB and photochemotherapy using psoralen plus UVA, alone and in combination with topical and systemic agents. We will also discuss the available data for the use of the excimer laser in the targeted treatment of psoriasis. Finally, where available, we will summarize the available data that compare the safety and efficacy of the different forms of UV light therapy. Psoriasis is a common, chronic, inflammatory, multisystem disease with predominantly skin and joint manifestations affecting approximately 2% of the population. In this fifth of 6 sections of the guidelines of care for psoriasis, we discuss the use of ultraviolet (UV) light therapy for the treatment of patients with psoriasis. Treatment should be tailored to meet individual patients' needs. We will discuss in detail the efficacy and safety as well as offer recommendations for the use of phototherapy, including narrowband and broadband UVB and photochemotherapy using psoralen plus UVA, alone and in combination with topical and systemic agents. We will also discuss the available data for the use of the excimer laser in the targeted treatment of psoriasis. Finally, where available, we will summarize the available data that compare the safety and efficacy of the different forms of UV light therapy. Adherence to these guidelines will not ensure successful treatment in every situation. Furthermore, these guidelines should not be deemed inclusive of all proper methods of care nor exclusive of other methods of care reasonably directed to obtaining the same results. The ultimate judgment regarding the propriety of any specific therapy must be made by the physician and the patient in light of all the circumstances presented by the individual patient. This fifth section will cover the management and treatment of psoriasis with phototherapy. A work group of recognized psoriasis experts was convened to determine the audience and scope of the guideline, and identify clinical questions to structure the primary issues in diagnosis and management discussed in American Academy of Dermatology (AAD) psoriasis guidelines sections 1 and 2.1Menter A. Gottlieb A. Feldman S.R. Van Voorhees A.S. Leonardi C.L. Gordon K.B. et al.Guidelines of care for the management of psoriasis and psoriatic arthritis: section 1. Overview of psoriasis and guidelines of care for the treatment of psoriasis with biologics.J Am Acad Dermatol. 2008; 58: 826-850Abstract Full Text Full Text PDF PubMed Scopus (940) Google Scholar, 2Gottlieb A. Korman N.J. Gordon K.B. Feldman S.R. Lebwohl M. Koo J.Y. et al.Guidelines of care for the management of psoriasis and psoriatic arthritis: section 2. Psoriatic arthritis: overview and guidelines of care for treatment with an emphasis on the biologics.J Am Acad Dermatol. 2008; 58: 851-864Abstract Full Text Full Text PDF PubMed Scopus (330) Google Scholar Work group members completed a disclosure of commercial support. An evidence-based model was used and evidence was obtained using a search of the MEDLINE database spanning the years 1960 through 2009. Only English-language publications were reviewed. The available evidence was evaluated using a unified system called the Strength of Recommendation Taxonomy developed by editors of the US family medicine and primary care journals (ie, American Family Physician, Family Medicine, Journal of Family Practice, and BMJ USA). This strategy was supported by a decision of the Clinical Guidelines Task Force in 2005 with some minor modifications for a consistent approach to rating the strength of the evidence of scientific studies.3Ebell M.H. Siwek J. Weiss B.D. Woolf S.H. Susman J.L. Ewigman B. et al.Simplifying the language of evidence to improve patient care: strength of recommendation taxonomy (SORT); a patient-centered approach to grading evidence in medical literature.J Fam Pract. 2004; 53: 111-120PubMed Google Scholar Evidence was graded using a 3-point scale based on the quality of methodology as follows:I.Good-quality patient-oriented evidence.II.Limited-quality patient-oriented evidence.III.Other evidence including consensus guidelines, opinion, or case studies. Clinical recommendations were developed on the best available evidence tabled in the guideline. These are ranked as follows:A.Recommendation based on consistent and good-quality patient-oriented evidence.B.Recommendation based on inconsistent or limited-quality patient-oriented evidence.C.Recommendation based on consensus, opinion, or case studies. In those situations where documented evidence-based data are not available, we have used expert opinion to generate our clinical recommendations. Prior guidelines on psoriasis were also evaluated. This guideline has been developed in accordance with the AAD “Administrative Regulations for Evidence-based Clinical Practice Guidelines,” which include the opportunity for review and comment by the entire AAD membership and final review and approval by the AAD Board of Directors. In the past, conventional psoriasis therapies–phototherapy, photochemotherapy, methotrexate, cyclosporine, and acitretin–were used when psoriasis was too extensive for topical therapy. Although a minimum body surface area (eg, 10%) has been traditionally used as a prerequisite to starting ultraviolet (UV) light or systemic therapy for psoriasis, a subset of patients with limited disease have debilitating symptoms. For example, whereas severe psoriasis of the palms and soles or severe scalp psoriasis affects less than 5% of the body surface area, the significant negative effect on the quality of life of the patient makes treatment with systemic therapies an appropriate approach to the management. Although treatment options for psoriasis have expanded in recent years, UV light therapy remains an essential therapeutic option for patients with psoriasis. Phototherapy is efficacious, is cost-effective, and generally lacks the systemic immunosuppressive properties of both traditional and biologic systemic therapies. Various spectra of UVB and UVA wavelengths have been used to treat psoriasis. Although it has been known for many centuries that some skin diseases improve with sun exposure, scientific investigation of phototherapeutic modalities did not begin until the late 19th century with the work of Niels Ryberg Finsen who received the Nobel Prize in 1903 for his work developing phototherapy for the treatment of cutaneous tuberculosis. Goeckerman4Goeckerman W. Treatment of psoriasis.Northwest Med. 1925; 24: 229-231Google Scholar first described the use of broadband (BB)-UVB in combination with day and night applications of crude coal tar for the successful treatment of psoriasis. This therapy was carried out while patients were admitted to the hospital for several weeks. During the years after the development of the Goeckerman4Goeckerman W. Treatment of psoriasis.Northwest Med. 1925; 24: 229-231Google Scholar regimen, several modifications and simplifications were made. In the 1950s, the Ingram5Ingram J.T. The significance and management of psoriasis.Br Med J. 1954; 2: 823-828Crossref PubMed Google Scholar regimen was developed, which replaced crude coal tar with anthralin. Subsequent studies have demonstrated that a lubricating base may be used instead of crude coal tar. However, a 1983 study demonstrated that suberythemogenic doses of UVB and coal tar were more efficacious than UVB and a lubricating base.6Lowe N.J. Wortzman M.S. Breeding J. Koudsi H. Taylor L. Coal tar phototherapy for psoriasis reevaluated: erythemogenic versus suberythemogenic ultraviolet with a tar extract in oil and crude coal tar.J Am Acad Dermatol. 1983; 8: 781-789Abstract Full Text PDF PubMed Scopus (0) Google Scholar, 7Lowe N.J. Contribution of topical tar oil to ultraviolet B phototherapy for psoriasis.J Am Acad Dermatol. 1986; 15: 1053-1055Abstract Full Text PDF PubMed Google Scholar Clear emollients such as mineral oil also enhance the efficacy of UVB by improving the optical properties of the skin; their use facilitated the shift of UVB as an outpatient, rather than an inpatient or day hospital, treatment modality.8Le Vine M.J. White H.A. Parrish J.A. Components of the Goeckerman regimen.J Invest Dermatol. 1979; 73: 170-173Abstract Full Text PDF PubMed Google Scholar, 9Berne B. Blom I. Spangberg S. Enhanced response of psoriasis to UVB therapy after pretreatment with a lubricating base: a single-blind controlled study.Acta Derm Venereol. 1990; 70: 474-477PubMed Google Scholar, 10LeVine M.J. Parrish J.A. Outpatient phototherapy of psoriasis.Arch Dermatol. 1980; 116: 552-554Crossref PubMed Google Scholar In the 1980s, a new type of UVB bulb with a narrow emission between 311 and 313 nm was developed and found to have superior efficacy to BB-UVB light11Walters I.B. Burack L.H. Coven T.R. Gilleaudeau P. Krueger J.G. Suberythemogenic narrow-band UVB is markedly more effective than conventional UVB in treatment of psoriasis vulgaris.J Am Acad Dermatol. 1999; 40: 893-900Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar; this new UVB treatment is now commonly referred to as narrowband (NB)-UVB therapy. Because keratinocyte hyperproliferation is a hallmark feature of psoriasis, it was originally believed that the mechanism of action of UV light treatment in psoriasis was through a direct effect of UV light on DNA by inhibition of cellular turnover. With newer evidence firmly demonstrating that psoriasis is an immunologic disease, the role of the immunosuppressive effects of UV light in the treatment of psoriasis has been better appreciated. UV light (both UVB and UVA) is locally immunosuppressive by its direct effects on Langerhans cells and indirect effects on numerous cytokines and adhesion molecules, which can lead to a switch from a T-helper (Th) 1 to a Th 2 phenotype.12Lui H. Phototherapy of psoriasis: update with practical pearls.J Cutan Med Surg. 2002; 6: 17-21Crossref PubMed Google Scholar, 13Zanolli M. Phototherapy treatment of psoriasis today.J Am Acad Dermatol. 2003; 49: S78-S86Abstract Full Text Full Text PDF PubMed Google Scholar Other effects of UV light include inhibition of both epidermal hyperproliferation and angiogenesis. Furthermore, UV light causes a selective reduction in T lymphocytes within psoriatic skin via apoptosis. BB-UVB, NB-UVB, and psoralen plus UVA (PUVA) can all induce apoptosis of T lymphocytes,14Krueger J.G. Wolfe J.T. Nabeya R.T. Vallat V.P. Gilleaudeau P. Heftler N.S. et al.Successful ultraviolet B treatment of psoriasis is accompanied by a reversal of keratinocyte pathology and by selective depletion of intraepidermal T cells.J Exp Med. 1995; 182: 2057-2068Crossref PubMed Scopus (0) Google Scholar, 15Ozawa M. Ferenczi K. Kikuchi T. Cardinale I. Austin L.M. Coven T.R. et al.312-Nanometer ultraviolet B light (narrow-band UVB) induces apoptosis of T cells within psoriatic lesions.J Exp Med. 1999; 189: 711-718Crossref PubMed Scopus (249) Google Scholar, 16Johnson R. Staiano-Coico L. Austin L. Cardinale I. Nabeya-Tsukifuji R. Krueger J.G. PUVA treatment selectively induces a cell cycle block and subsequent apoptosis in human T-lymphocytes.Photochem Photobiol. 1996; 63: 566-571Crossref PubMed Google Scholar which may play an important role in the mechanism involved in remissions of psoriasis. Ancient Egyptians knew that natural photosensitizing compounds found in plants, combined with exposure to natural sunlight, were effective for the treatment of vitiligo. Trimethylpsoralen, a synthetic psoralen, was first used for the treatment of vitiligo and has since been used to successfully treat many other inflammatory photosensitive diseases such as cutaneous T-cell lymphoma, atopic dermatitis, and lichen planus.17Morison W.L. Psoralen ultraviolet A therapy in 2004.Photodermatol Photoimmunol Photomed. 2004; 20: 315-320Crossref PubMed Scopus (0) Google Scholar In the 1970s, oral ingestion of 8-methoxypsoralen combined with high-intensity UVA (known as PUVA photochemotherapy) was shown to be effective for the treatment of psoriasis18Parrish J.A. Fitzpatrick T.B. Tanenbaum L. Pathak M.A. Photochemotherapy of psoriasis with oral methoxsalen and longwave ultraviolet light.N Engl J Med. 1974; 291: 1207-1211Crossref PubMed Google Scholar; in 1982 PUVA was Food and Drug Administration (FDA) approved for psoriasis. All patients who are considered for treatment with phototherapy or photochemotherapy must have a complete history and physical examination. Patients with a known history of lupus erythematosus or xeroderma pigmentosum should not be treated with phototherapy or photochemotherapy. Patients with a history of a photosensitivity disorder, taking photosensitizing medications, with a history of melanoma, with atypical nevi, with multiple risk factors for melanoma, with multiple nonmelanoma skin cancers, or who are immunosuppressed as a result of organ transplantation should be screened carefully before initiating phototherapy or photochemotherapy. They should also be advised that adherence to their follow-up visits is imperative to obtaining maximal results. Office phototherapy and photochemotherapy should be performed under the direction of a dermatologist with the appropriate training and expertise in this area. Experts recommend that patients be examined approximately once a month or more often if necessary, although specific data on the frequency of evaluations during phototherapy or photochemotherapy are lacking. Each patient's treatment should be closely monitored by a nurse or phototherapy technician with proper training, and any abnormal findings should be transmitted to the treating dermatologist. All phototherapy equipment should be maintained and regularly calibrated by appropriately trained personnel. Accurate records of the dosage and number of treatments along with any side effects should be maintained for every patient. Traditional BB-UVB radiation has been used for the treatment of psoriasis for more than 75 years. In recent years phototherapy has maintained its important role in the treatment of psoriasis, either as monotherapy or in combination with topical or systemic agents. In a study published in 1975, it was shown that 313 nm was the most effective wavelength in clearing psoriasis.19Alsins J. Claesson S. Fischer T. Juhlin L. Development of high intensity narrow-band lamps and studies of the irradiation effect on human skin: irradiation with high intensity lamps.Acta Derm Venereol. 1975; 55: 261-271PubMed Google Scholar Further study using monochromatic UV radiation ranging from 254 to 313 nm revealed that suberythemogenic exposure to 313-nm light led to significant improvement of psoriasis.20Parrish J.A. Jaenicke K.F. Action spectrum for phototherapy of psoriasis.J Invest Dermatol. 1981; 76: 359-362Abstract Full Text PDF PubMed Google Scholar UVB interferes with the synthesis of proteins and nucleic acids, which leads to a decreased proliferation of epidermal keratinocytes. Early changes after exposure to UV radiation include formation of pyrimidine dimers, membrane lipid peroxidation, and induction of transcriptional factors. Delayed changes include alteration of antigen-presenting cells and cellular signaling mechanisms.13Zanolli M. Phototherapy treatment of psoriasis today.J Am Acad Dermatol. 2003; 49: S78-S86Abstract Full Text Full Text PDF PubMed Google Scholar UVB decreases the number of Langerhans cells21Duthie M.S. Kimber I. Norval M. The effects of ultraviolet radiation on the human immune system.Br J Dermatol. 1999; 140: 995-1009Crossref PubMed Scopus (187) Google Scholar thus inhibiting the ability of dendritic cells to present antigens, secondary to membrane damage and reduction in the expression of cell surface molecules while altering the secretion of cytokines in the macrophages.22Sethi G. Sodhi A. Role of p38 mitogen-activated protein kinase and caspases in UV-B-induced apoptosis of murine peritoneal macrophages.Photochem Photobiol. 2004; 79: 48-54PubMed Google Scholar The newly discovered subset of T cells, Th17 cells, are now considered to play a central role in the immunopathogenesis of psoriasis and are likewise down-regulated by UVB.23Nickoloff B.J. Cracking the cytokine code in psoriasis.Nat Med. 2007; 13: 242-244Crossref PubMed Scopus (140) Google Scholar Early studies demonstrated the efficacy of BB-UVB monotherapy in psoriasis. One study reported resolution of psoriasis in 20 of 28 patients treated with erythemogenic doses of home-based UVB therapy24Larko O. Swanbeck G. Home solarium treatment of psoriasis.Br J Dermatol. 1979; 101: 13-16Crossref PubMed Google Scholar whereas another study demonstrated efficacy in 18 of 20 patients treated with 3 times weekly outpatient UVB phototherapy with concomitant white petrolatum.25Adrian R.M. Parrish J.A. Momtaz T.K. Karlin M.J. Outpatient phototherapy for psoriasis.Arch Dermatol. 1981; 117: 623-626Crossref PubMed Google Scholar Similar observations were made by Levine and Parrish10LeVine M.J. Parrish J.A. Outpatient phototherapy of psoriasis.Arch Dermatol. 1980; 116: 552-554Crossref PubMed Google Scholar when white petrolatum was combined with UV. Remission times were prolonged using maintenance therapy.26Boer J. Schothorst A.A. Suurmond D. UV-B phototherapy of psoriasis.Dermatologica. 1980; 161: 250-258Crossref PubMed Google Scholar, 27Stern R.S. Armstrong R.B. Anderson T.F. Bickers D.R. Lowe N.J. Harber L. et al.Effect of continued ultraviolet B phototherapy on the duration of remission of psoriasis: a randomized study.J Am Acad Dermatol. 1986; 15: 546-552Abstract Full Text PDF PubMed Google Scholar, 28Boztepe G. Karaduman A. Sahin S. Hayran M. Kolemen F. The effect of maintenance narrow-band ultraviolet B therapy on the duration of remission for psoriasis: a prospective randomized clinical trial.Int J Dermatol. 2006; 45: 245-250Crossref PubMed Scopus (0) Google Scholar The advent of NB-UVB lamps improved the use of UVB therapy in psoriasis and is widely considered to be preferable to BB-UVB therapy. NB-UVB use was initially popularized in the United Kingdom and Europe in the mid-1980s, and became available in the United States approximately one decade later. Many of the studies evaluating NB-UVB were right-left half body comparisons of NB-UVB with BB-UVB.11Walters I.B. Burack L.H. Coven T.R. Gilleaudeau P. Krueger J.G. Suberythemogenic narrow-band UVB is markedly more effective than conventional UVB in treatment of psoriasis vulgaris.J Am Acad Dermatol. 1999; 40: 893-900Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar, 29Karvonen J. Kokkonen E.L. Ruotsalainen E. 311 nm UVB lamps in the treatment of psoriasis with the Ingram regimen.Acta Derm Venereol. 1989; 69: 82-85PubMed Google Scholar, 30Larko O. Treatment of psoriasis with a new UVB-lamp.Acta Derm Venereol. 1989; 69: 357-359PubMed Google Scholar, 31Coven T.R. Burack L.H. Gilleaudeau R. Keogh M. Ozawa M. Krueger J.G. Narrowband UV-B produces superior clinical and histopathological resolution of moderate-to-severe psoriasis in patients compared with broadband UV-B.Arch Dermatol. 1997; 133: 1514-1522Crossref PubMed Google Scholar One such study demonstrated that although 60% of patients had the same efficacy regardless of which type of UVB was used, 40% of patients treated with NB-UVB had superior results.29Karvonen J. Kokkonen E.L. Ruotsalainen E. 311 nm UVB lamps in the treatment of psoriasis with the Ingram regimen.Acta Derm Venereol. 1989; 69: 82-85PubMed Google Scholar Other similar studies have demonstrated more rapid clearing in patients treated with NB-UVB compared with those treated with BB-UVB11Walters I.B. Burack L.H. Coven T.R. Gilleaudeau P. Krueger J.G. Suberythemogenic narrow-band UVB is markedly more effective than conventional UVB in treatment of psoriasis vulgaris.J Am Acad Dermatol. 1999; 40: 893-900Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar, 30Larko O. Treatment of psoriasis with a new UVB-lamp.Acta Derm Venereol. 1989; 69: 357-359PubMed Google Scholar and treatment with NB-UVB was more likely than BB-UVB to lead to histopathological resolution of psoriasis lesions (88% compared with 59%).31Coven T.R. Burack L.H. Gilleaudeau R. Keogh M. Ozawa M. Krueger J.G. Narrowband UV-B produces superior clinical and histopathological resolution of moderate-to-severe psoriasis in patients compared with broadband UV-B.Arch Dermatol. 1997; 133: 1514-1522Crossref PubMed Google Scholar The potential value of maintenance therapy with NB-UVB has also been evaluated. After 12 weeks of NB-UVB therapy, 55% of patients who received NB-UVB twice weekly for 4 weeks followed by once weekly for 4 weeks were in remission at 1 year compared with 33% of patients who did not receive maintenance therapy.24Larko O. Swanbeck G. Home solarium treatment of psoriasis.Br J Dermatol. 1979; 101: 13-16Crossref PubMed Google Scholar A standard protocol is recommended for the use of phototherapy in the management of psoriasis. Basic phototherapy education should be given to all patients. This must include education about the use of goggles in all patients and the use of genital shields in male patients. The dosage of UVB may be administered according to the Fitzpatrick skin type32Wolff K. Gschnait F. Honigsmann H. Konrad K. Parrish J.A. Fitzpatrick T.B. Phototesting and dosimetry for photochemotherapy.Br J Dermatol. 1977; 96: 1-10Crossref PubMed Google Scholar or the minimal erythema dose (MED), with subsequent dosages adjusted accordingly. (Please see Table I, Table II for examples of well-accepted, published guidelines for dosing of both BB-UVB and NB-UVB.)Table IDosing guidelines for broadband ultraviolet BAccording to skin type:Skin typeInitial UVB dose, mJ/cm2UVB increase after each treatment, mJ/cm2I205II2510III3015IV4020V5025VI6030According to MED:Initial UVB50% of MEDTreatments 1-10Increase by 25% of initial MEDTreatments 11-20Increase by 10% of initial MEDTreatments ≥21As ordered by physicianIf subsequent treatments are missed for:4-7 dKeep dose same1-2 wkDecrease dose by 50%2-3 wkDecrease dose by 75%3-4 wkStart overMED, Minimal erythema dose; UV, ultraviolet.Administered 3-5×/wk.Adapted with permission from Zanolli et al.169Zanolli M.D. Feldman S.R. Phototherapy treatment protocols for psoriasis and other phototherapy responsive dermatoses. 2nd ed. Informa Healthcare, New York2004Crossref Google Scholar Open table in a new tab Table IIDosing guidelines for narrowband ultraviolet BAccording to skin type:Skin typeInitial UVB dose, mJ/cm2UVB increase after each treatment, mJ/cm2Maximum dose, mJ/cm2I130152000II220252000III260403000IV330453000V350605000VI400655000According to MED:Initial UVB50% of MEDTreatments 1-20Increase by 10% of initial MEDTreatments ≥21Increase as ordered by physicianIf subsequent treatments are missed for:4-7 dKeep dose same1-2 wkDecrease dose by 25%2-3 wkDecrease dose by 50% or start over3-4 wkStart overMaintenance therapy for NB-UVB after >95% clearance:1×/wkNB-UVB for 4 wkKeep dose same1×/2 wkNB-UVB for 4 wkDecrease dose by 25%1×/4 wkNB-UVB50% of Highest doseMED, Minimal erythema dose; NB, narrowband; UV, ultraviolet.Administered 3-5×/wk.Because there is broad range of MED for NB-UVB by skin type, MED testing is generally recommended.It is critically important to meter UVB machine once weekly. UVB lamps steadily lose power. If UV output is not periodically measured and actual output calibrated into machine, clinician may have false impression that patient can be treated with higher doses when machine is actually delivering much lower dose than number entered.Minimum frequency of phototherapy sessions required per week for successful maintenance as well as length of maintenance period varies tremendously between individuals. Above table represents most ideal situation where patient can taper off phototherapy. In reality, many patients require 1×/wk NB-UVB phototherapy indefinitely for successful long-term maintenance.Adapted with permission from Do and Koo.170Do A. Koo J. Initiating narrow-band UVB for the treatment of psoriasis: how to do MED skin testing.Psoriasis Forum. 2004; 10: 7-11Crossref Google Scholar Open table in a new tab MED, Minimal erythema dose; UV, ultraviolet. Administered 3-5×/wk. Adapted with permission from Zanolli et al.169Zanolli M.D. Feldman S.R. Phototherapy treatment protocols for psoriasis and other phototherapy responsive dermatoses. 2nd ed. Informa Healthcare, New York2004Crossref Google Scholar MED, Minimal erythema dose; NB, narrowband; UV, ultraviolet. Administered 3-5×/wk. Because there is broad range of MED for NB-UVB by skin type, MED testing is generally recommended. It is critically important to meter UVB machine once weekly. UVB lamps steadily lose power. If UV output is not periodically measured and actual output calibrated into machine, clinician may have false impression that patient can be treated with higher doses when machine is actually delivering much lower dose than number entered. Minimum frequency of phototherapy sessions required per week for successful maintenance as well as length of maintenance period varies tremendously between individuals. Above table represents most ideal situation where patient can taper off phototherapy. In reality, many patients require 1×/wk NB-UVB phototherapy indefinitely for successful long-term maintenance. Adapted with permission from Do and Koo.170Do A. Koo J. Initiating narrow-band UVB for the treatment of psoriasis: how to do MED skin testing.Psoriasis Forum. 2004; 10: 7-11Crossref Google Scholar Acute side effects with BB-UVB therapy include erythema, itching, burning, and stinging. The use of eye protection with goggles is required to decrease the risk of UVB-related cataract formation. Reactivation of herpes simplex virus infection may occur after UVB treatment. Photoaging is a long-term side effect, and features of dermatoheliosis including wrinkling, lentigines, and telangiectasias may occur. Photocarcinogenesis is a potential adverse effect of UVB phototherapy; however, numerous studies have failed to show such an effect in patients with psoriasis after UVB therapy.33Stern R.S. Laird N. The carcinogenic risk of treatments for severe psoriasis: photochemotherapy follow-up study.Cancer. 1994; 73: 2759-2764Crossref PubMed Scopus (0) Google Scholar, 34Lee E. Koo J. Berger T. UVB phototherapy and skin cancer risk: a review of the literature.Int J Dermatol. 2005; 44: 355-360Crossref PubMed Scopus (141) Google Scholar Long-term exposure to BB-UVB (>300 treatments) may be associated with an increased risk of genital tumors in men treated without genital shielding; the routine use of shields has been recommended to avoid such an effect.35Studniberg H.M. Weller P. PUVA, UVB, psoriasis, and nonmelanoma skin cancer.J Am Acad Dermatol. 1993; 29: 1013-1022Abstract Full Text PDF PubMed Google Scholar In addition to genital shielding, standard practice involves covering the face as long as there are no lesions of psoriasis on the face or, if there are, minimizing the dose to the face as lesions on the face tend to respond to lower doses of UVB compared with lesions on trunk or extremities. Burning with NB-UVB is generally comparable with that observed with BB-UVB exposure. Although NB-UVB is reported to be less phototoxic than BB-UVB in some studies,36Storbeck K. Holzle E. Schurer N. Lehmann P. Plewig G. Narrow-band U.V.B. (311 nm) versus conventional broad-band UVB with and without dithranol in phototherapy for psoriasis.J Am Acad Dermatol. 1993; 28: 227-231Abstract Full Text PDF PubMed Google Scholar, 37Picot E. Meunier L. Picot-Debeze M.C. Peyron J.L. Meynadier J. Treatment of psoriasis with a 311-nm UVB lamp.Br J Dermatol. 1992; 127: 509-512Crossref PubMed Scopus (114) Google Scholar other studies failed to show this discrepancy.31Coven T.R. Burack L.H. Gilleaudeau R. Keogh M. Ozawa M. Krueger J.G. Narrowband UV-B produces superior clinical and histopathological resolution of moderate-to-severe psoriasis in patients compared with broadband UV-B.Arch Dermatol. 1997; 133: 1514-1522Crossref PubMed Google Scholar, 38Alora M.B. Taylor C.R. Narrow-band (311 nm) UVB phototherapy: an audit of the first year's experience at the Massachusetts General Hospital.Photodermatol Photoimmunol Photomed. 1997; 13: 82-84Crossref PubMed Google Scholar Although an unusual occurrence, lesional blistering has also been reported after exposure to NB-UVB.39George S.A. Ferguson J. Lesional blistering following narrow-band (TL-01) UVB phototherapy for psoriasis: a report of four cases.Br J Dermatol. 1992; 127: 445-446Crossref PubMed Scopus (0) Google Scholar Murine models of photocarcinogenesis suggest that NB-UVB may be 2 to 3 times more carcinogenic per MED as compared with BB-UVB.40Flindt-Hansen H. McFadden N. Eeg-Larsen T. Thune P. Effect of a new narrow-band UVB lamp on photocarcinogenesis in mice.Acta Derm Venereol. 1991; 71: 245-248PubMed Google Scholar, 41Gibbs N.K. Traynor N.J. MacKie R.M. Campbell I. Johnson B.E. Ferguson J. The phototumorigenic potential of broad-band (270-350 nm) and narrow-band (311-313 nm) phototherapy sources cannot be predicted by their edematogenic potential in hairless mouse skin.J Invest Dermatol. 1995; 104: 359-363Abstract Full Text PDF PubMed Google Scholar However, because of the higher efficacy of NB-UVB