circumscribed myxedema


Myxedema (British English: myxoedema) is a skin and tissue disorder usually due to severe prolonged hypothyroidism. Hypothyroidism can be caused by atrophic disease, Hashimoto's thyroiditis, surgical removal of the thyroid, and rarer conditions. Partial forms of myxedema, especially of the lower legs (called pretibial myxedema), occasionally occur in adults with Graves' disease, a cause of hyperthyroidism; or also Hashimoto's thyroiditis without severe hypothyroidism.


Myxedema usually presents itself with some of the following symptoms:


Myxedema, stemming from both the hyperthyroid and hypothyroid conditions, results from the accumulation of increased amounts of hyaluronic acid and chondroitin sulfate in the dermis in both lesional and normal skin. The mechanism that causes myxedema is still not yet understood, although animal model studies suggest that thyroid hormones affect the synthesis and catabolism of mucopolysaccharides and collagen by dermal fibroblasts. The fibroblasts in the orbital and pretibial dermis share antigenic sites that underlie the autoimmune process that causes Graves' disease. This cross-reaction may contribute to the development of myxedema long after normal levels of thyroid hormones have been restored by treatment.


Treatment for myxedema is difficult. Systemic or intralesional glucocorticoids, topical glucocorticoids under occlusion or high-dose intravenous immunoglobulin have been reported to offer some relief to patients. Treatment should follow correction of the original hyperthyroidism/hypothyroidism.

See also

Severe hypothyroidism in a child is called Cretinism.

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