(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
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
by dermal fibroblasts
. The fibroblasts in the orbital
and pretibial dermis
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
or high-dose intravenous immunoglobulin
have been reported to offer some relief to patients.
Treatment should follow correction of the original hyperthyroidism/hypothyroidism.
Severe hypothyroidism in a child is called Cretinism