Scleromyxedema with myopathy and hyperthyroidism.

We describe a 62-year-old woman who developed extensive papular skin eruption with dysphagia and proximal muscle weakness. Laboratory studies showed a progressive increase of muscle enzymes, lambda monoclonal gammopathy, and elevated serum thyroid hormones. Several skin and muscle biopsies were necessary to reach the correct diagnosis of scleromyxedema in association with hyperthyroidism. Muscle biopsies contained rimmed vacuoles with some necrosis and regeneration, but no increased mucopolysaccharides. Hyperthyroidism was treated without appreciable improvement of the skin and muscle lesions. Myopathy is an increasingly recognized feature of scleromyxedema; its pathogenesis is still unexplained.