Background: No published data exist on the incidence of liver fibrosis in patients with dermatomyositis treated with methotrexate. Objective: Our purpose was to examine the efficacy, steroid-sparing potential, and side effects of methotrexate in patients with dermatomyositis and to report liver biopsy results in four patients. Methods: A retrospective review of all cases of dermatomyositis treated with methotrexate in a dermatology and rheumatology referral practice was conducted. Results: Of the 10 cases reviewed, seven were of dermatomyositis whereas three were of amyopathic dermatomyositis (ADM). Nine patients received oral methotrexate. One patient received intravenous methotrexate. Improvement of cutaneous disease occurred in seven (100%) of the patients with dermatomyositis and in two (66%) of those with ADM; myositis improved in four (57%) of the patients with dermatomyositis. The initial prednisone dose was halved after an average of 18 weeks of methotrexate therapy in the patients with dermatomyositis and 13 weeks in the patients with ADM. Methotrexate-related side effects occurred in six (86%) of the patients with dermatomyositis and in one (33%) of the patients with ADM. Of the four patients who had liver biopsies, two (50%) showed mild hepatic fibrosis, resulting in discontinuation of the drug. Both patients in whom fibrosis developed had preexisting steroid-induced diabetes mellitus. Conclusion: Although methotrexate is an effective treatment for dermatomyositis, side effects are common. Patients with diabetes mellitus should be closely monitored for toxic effects on the liver.
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