methimazole and Lupus-Vulgaris

Over the past four decades, a great deal has been learned about the pharmacology and mechanisms of action of antithyroid drugs. Their ability to inhibit hormone biosynthesis involves complex interactions with thyroid peroxidase and thyroglobulin, many of which are still poorly understood. Their spectrum of activity is much wider than previously thought, and a number of clinically important extrathyroidal actions have been identified. Despite a greater appreciation for the intricacies of antithyroid-drug pharmacology, controversies still surround the use of these agents in the treatment of thyrotoxicosis. These controversies are apt to continue until the pathophysiology of Graves' disease is fully elucidated.

Topics: Adult; Agranulocytosis; Autoimmune Diseases; Chemical and Drug Induced Liver Injury; Child; Female; Fetus; Graves Disease; Humans; Hyperthyroidism; Immunity; Immunoglobulins; Infant, Newborn; Insulin Antibodies; Leukopenia; Lupus Vulgaris; Methimazole; Milk, Human; Pregnancy; Pregnancy Complications; Propylthiouracil; Vascular Diseases

A 24-year-old woman with Graves' disease treated with methimazole for 4 years, developed recalcitrant ulcers on the lower legs. Histological studies demonstrated vasculitis in deep dermal vessels accompanied by C3 deposition. Laboratory investigation revealed lupus-like abnormalities (leucocytopenia, positive antinuclear and antidouble strand (ds) DNA antibodies, and positive ANCA). The leg ulcers dramatically improved after methimazole was withdrawn. In addition, leucocytopenia and the immunological abnormalities soon faded. Although lupus-like syndrome is well known to be induced by antithyroid drugs, vasculitis is a rare complication. To the best of our knowledge, this is the first report describing ANCA-associated vasculitis caused by methimazole.

Topics: Adult; Antibodies, Antineutrophil Cytoplasmic; Antithyroid Agents; Autoantibodies; Biomarkers; Female; Graves Disease; Humans; Lupus Vulgaris; Methimazole; Skin Ulcer; Vasculitis