Myxedema describes a specific form of cutaneous and dermal edema secondary to increased deposition of connective tissue components. These can include glycosaminoglycans, hyaluronic acid, and other mucopolysaccharides.[4] The increased deposition of glycosaminoglycan is not fully understood, however two mechanisms predominate:
Fibroblast stimulation. It is thought that fibroblast stimulation by the thyroid stimulating hormone (TSH) receptor increases the deposition of glycosaminoglycan, which results in an osmotic edema and fluid retention. It is thought that many cells responsible for forming connective tissue react to increases in TSH levels.[citation needed]
Lymphocyte stimulation. In Basedow-Graves' thyroid disease, lymphocytes react against the TSH receptor. Lymphocytes react not only against thyroid receptors, but also any tissue with cells expressing the receptor. This can lead to tissue damage and scar tissue formation, explaining the deposition of glycosaminoglycans