Pretibial Myxedema
Pretibial myxedema, also known as thyroid dermopathy, has been associated with thyroid disease usually Graves disease even though it's not related to thyroid function. However, it can also occur in patients with Hashimoto's thyroiditis, primary hypothyroidism or even euthyroidism. It occurs due to deposition and accumulation of excessive glycosaminoglycans, particularly hyaluronic acid, in the dermis. It usually affects females. The most common site are the shins (pretibial areas) and dorsum of the feet. Pretibial myxedema is usually asymptomatic but the lesions may be itchy or sore. They appear swollen and lumpy and the early lesions are bilateral and firm. They may be non-pitting, asymmetrical plaques or nodules and may coalesce to form scaly, thickened and hardened skin areas. The lesions may have prominent hair follicles giving a PEAU D'ORANGE (orange peel) texture. The overlying skin may be slightly pigmented yellow-brown. The lesions may also have hyperhidrosis or hypertrichosis.