Dermal mucinosis and musculoskeletal symptoms simulating polymyositis as a presenting sign of hypothyroidism.

A case of dermal mucinosis and musculoskeletal symptoms simulating polymyositis as a presenting sign of hypothyroidism is presented. The patient presented muscle weakness and edema of the face including the eyelids. Laboratory examination revealed elevated creatinine phosphokinase, decreased free-T4, decreased free-T3, elevated TSH, positive anti-microsome antibody and positive anti-TSH receptor antibody. The skin biopsy specimen revealed swelling of the collagen bundles with the bundles splitting up into individual fibers, with some blue threads and granules of mucin interspersed. Alucian blue stain demonstrated vast amounts of mucin throughout the whole dermis, which was completely removed on incubation with Streptomyces hyaluronidase. The patient was diagnosed as having hypothyroidism due to Hashimoto's disease with possible polymyositis complications. After two months of thyroid hormone replacement therapy, she was euthyroidic and discharged. These results indicate that our case was a rare case of severe generalized myxoedema due to hypothyroidism of Hashimoto's disease simulating the musculoskeletal symptoms of polymyositis.