Photohterapy

74 Review Article Phototherapy* Fototerapia* Ida Duarte 1 Roberta Buense 2 Clarice Kobata 3 Abstract: Phototherapy has been used to treat a large variety of dermatoses since the past century. It is classified according to the type of irradiation (UVA or UVB). Phototherapy is indicated for all types of inflammatory and chronic skin diseases, such as vitiligo, psoriasis, parapsoriasis, cutaneous T-cell lymphomas and chronic eczemas, with good therapeutic results. It can be used as monotherapy or associated with others drugs, such as retinoids, methotrexate and cyclosporine, aiming to reduce length of treatment and doses. Like other treatments, phototherapy has some limitations - it requires specific equipment, patient's compliance, has restricted indications and leads to cumulative UV doses. The therapy must be performed with strict follow-up to obtain effective therapeutic response and few adverse effects. Keywords: Inflammation; Phototherapy; PUVA therapy; Ultraviolet rays Resumo: Fototerapia é utilizada para tratar uma grande variedade de dermatoses. Desde o século passado a fototerapia tem sido utilizada em várias modalidades, com irradiação UVA ou UVB. Está indicada para todos os tipo de dermatoses inflamatórias e com período crônico de evolução, como vitiligo, pasoríase, parapsoríase, linfomas cutâneos de células T, eczemas crônicos, demonstrando bons resultados terapêuticos. Pode ser utilizada como monoterapia ou associada a outras drogas, como retinóides, metotrexate, ciclosporina, com objetivo de diminuir o tempo de tratamento e as doses das medicações mencionadas. Como os demais tipos de tratamento, a fototerapia apresenta algumas limitações, como a necessidade de equipamentos específicos, a adesão do paciente, a possibilidade de indicação ao paciente e a dose cumulativa de irradiação UV. A fototerapia deve ser conduzida com seguimento criterioso para a obtenção de resposta efetiva com poucos efeitos colaterais. Palavras-chave: Fototerapia; Inflamação; Raios ultravioleta; Terapia PUVA INTRODUCTION Phototherapy is a type of therapy used to treat several dermatoses. Its use dates back to Antiquity and is classified according to the type of radiation used (UVA or UVB), which varies depending on the wavelength. This is a treatment option for various chronic skin diseases such as psoriasis, vitiligo, cutaneous T-cell lymphoma, parapsoriasis, and eczemas, among others, and produces very good results. Additionally, phototherapy may be used in association with several systemic drugs, such as retinoids, methotrexate and cyclosporin in order to attain rapid control of the dermatosis with smaller doses of medication. As is true with any other curative option, phototherapy has limitations such as the use of specialized equipment, patient compliance with treatment, and clinical issues as the total cumulative UV radiation dose and its consequences. The use of phototherapy requires caution and strict follow-up to achieve an effective therapeutic * Work done at Clínica de Dermatologia da Santa Casa de São Paulo - São Paulo (SP), Brazil. Conflict of interests: None 1 2 3 Adjunct Professor, Faculdade de Ciências Médicas da Santa Casa de São Paulo. Head of the Allergy and Phototherapy Division, Dermatology Clinic, Santa Casa de Misericórdia de São Paulo - São Paulo (SP), Brazil. Graduate student in Dermatology from the Universidade de São Paulo - USP. Dermatologist, volunteer at the Allergy and Phototherapy Division, Dermatology Clinic, Santa Casa de Misericórdia de São Paulo - São Paulo (SP), Brazil. Dermatologist, volunteer at the Allergy and Phototherapy Division, Dermatology Clinic, Santa Casa de Misericórdia de São Paulo - São Paulo (SP), Brazil. ©2006 by Anais Brasileiros de Dermatologia An Bras Dermatol. 2006;81(1):74-82. Phototherapy response and avoid undesirable side effects. BACKGROUND The first descriptions on the use of phototherapy date back to 1400 and refer to the Hindu [practice and] use of medicinal plants associated with exposure to the sun for treating vitiligo.1 However, it was only after 1903, when Niels Finsen was awarded the Nobel prize for his success in treating lupus vulgaris with UV radiation, that phototherapy began to be truly studied and practiced as a treatment for various skin diseases. During the First World War (1914-1918), the treatment of traumatic ulcers with phototherapy and solar light began and produced good results.1 In 1925, Goeckerman introduced the combination of coal tar and ultraviolet radiation in treating psoriasis,2 a regimen that was used for a long time. In 1948, Mofty reported the effects obtained with 8-MOP in treating vitiligo, and was followed by Lener, who showed the possibility of enhancing the effects of this substance by the use of UV radiation between 320400 nm, constituting what is known as the PUVA treatment. In 1974, several authors (Parrish, Fitzpatrick, Tannenbaum et al.) reported on the beneficial effects of this type of therapy in psoriasis.3 Since then, another series of diseases has been described as responsive to UV radiation as well. The greatest leap forward was given with the discovery, in 1988,1 that a small range of UVB radiation, between 311 and 313 nm, called narrowband UVB would be more efficacious than UVB in treating psoriasis. PHOTOBIOLOGY Ultraviolet rays correspond to 5% of solar light on the Earth and represent a small part of the electromagnetic spectrum. Other regions of this spectrum include microwaves, radio waves, infrared radiation, visible light, X-rays, and gamma radiation.4 The wavelength of each type of radiation is what defines its characteristics. Ultraviolet rays are divided into UVA: 400-320 nanometers (nm), UVB: 320-290 nm and UVC: 290200 nm. UVA is subdivided into UVA I (340-400 nm) and UVA II (320-340 nm), and the UVB range between 311 and 312 nm is called narrowband UVB. UVA radiation reaches the epidermal and superficial and mid dermal skin layers and UVB reaches mainly the epidermis. Both UVB and UVA act on keratinocytes. UV light is absorbed by nucleotides and leads to the formation of DNA photoproducts, especially pyrimidine bases. This sets off photochemical reactions that result in biochemical changes in the tissues, such as induction of the activity of some 75 enzymes, cytokine secretion, and repair of structures.5 All reactions depend on the wavelength employed. The molecules in the skin that absorb light are called chromophores.5 The most important chromophore is melanin that absorbs both UVA and UVB radiation. DNA is the most important chromophore for photobiological response in the UVB scale. Triptophan, 7-dehydrocholesterol, urocanic acid, pyridoline (collagen), and desmosine (elastin) are also chromophores for UVB. NAD and FAD co-factors are chromophores for UVA. Not all chromophores are capable of initiating a photochemical reaction in the skin. The main responses induced by ultraviolet radiation on the skin are: 1- Anti-inflammatory / immunosu (...truncated)