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Spring 2009, Vol. 17 No. 1

Hong Kong J. Dermatol. Venereol. (2009) 17, 21-23


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Long story, short hairs

NM Luk 陸乃明

Abstract
Psoriasis is a common, chronic and non-infectious skin disease characterised by well-defined erythematous plaques and papules with silvery scales and typical extensor distribution. It is a common skin disease which is sometimes refractory to treatment. Methotrexate, which was initially used to treat cancer, was discovered to be effective in clearing psoriasis in the 1950s. However, the use of methotrexate is associated with severe adverse reactions including acute haematologic toxicity and hepatotoxicity. Methotrexate should therefore be limited to patients with moderate to severe psoriasis and should not be prescribed to people who have had liver disease or preexisting blood dyscrasias. Careful selection of patients, pretreatment evaluation and close monitoring of patients after commencing methotrexate is essential. Laboratory tests should include regular complete blood count, renal and liver function tests, and liver biopsy after life cumulative dose of 1.0 to 1.5 g is reached. Moreover, folate is often added because it has been shown that folate supplementation during methotrexate therapy can alleviate both toxicity and adverse effects without jeopardising its efficacy.