Pretibial myxedema as the initial manifestation of Graves' disease

Abstract

Pretibial myxedema (PM) is a localized thickening of the pretibial skin due to accumulation of acid mucopolysacharides (glycosaminoglycans). Its pathogenesis is still under investigation. Pretibial myxedema, exophthalmus and thyroid acropachy are the classic extrathyroidal manifestations of Graves' disease. Almost invariably, PM follows the onset of ophthalmopathy, developing after the diagnosis and treatment of hyperthyroidism. Pretibial myxedema preceding Graves' ophthalmopathy is rare. We report the case of a 28-year-old Greek woman, who presented with multiple, asymptomatic nodules and plaques of the lower legs in the absence of other physical findings. Histopathologic examination revealed deposition of mucopolysacharides in the lower dermis. Laboratory investigation showed elevated serum T3 and T4 and depressed TSH levels. In our patient, pretibial myxedema was the earliest manifestation, leading to the diagnosis of Graves' disease.