Pretibial myxoedema

Definition

Pretibial myxoedema is a form of diffuse cutaneous mucinosis in which there is an accumulation of excess glycosaminoglycans, especially hyaluronic acid, in the dermis and subcutis. It is most commonly seen on the shins (pretibial areas) but does occur elsewhere on the lower extremities. It manifests as violaceous or brownish, firm, non-pitting, asymmetrical nodules or plaques or nodules which tend to coalesce to produce extensive areas of induration with a "peau d'orange" (orange peel) appearance. It is nearly always associated with autoimmune thyroiditis (Graves disease) and may be associated with finger clubbing (acropachy) and exophthalmos (thyroid eye disease).

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