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Skin Changes in Graves' Disease

© Elaine Moore

Hyperthyroidism in Graves’ disease may (GD) cause changes in the skin’s dermal layer, affecting the appearance of the skin as well as the hair and nails. Because of the increased circulation, both hair and nails may experience excess growth and brittleness. Patients with Graves’ disease usually have skin that is moist, velvety and flushed.

Although hyperthyroidism is the primary complaint of GD, a minority of patients may also develop specific Graves’ related skin and eye disorders. These conditions are known respectively as Graves' dermopathy and Graves' ophthalmopathy (GO). A small number of Graves' disease patients develop only GO and or Graves' dermopathy without ever developing clinically evident hyperthyroidism. The dermatological conditions or skin disorders associated with GD include pretibial myxedema (PTM), and rarely acropachy. Acropachy is an inflammatory disorder involving the soft connective tissue of the fingers and toes and it may progress to a condition of elephantiasis. Vitiligo, an autoimmune condition characterized by unpigmented patches of skin, is seen in nearly 7% of Graves’ disease patients.

Patients who develop both hyperthyroidism and extrathyroidal (non-thyroid) Graves' symptoms generally develop hyperthyroidism first. The eye and skin disorders then develop within eighteen months of the onset of hyperthyroidism. However, in a small number of patients, extrathyroidal symptoms develop first.

PTM occurs in about 2% to 3% of GD patients and it may also rarely occur in patients with Hashimoto's thyroiditis. Approximately 7% of patients with PTM go on to develop acropachy. The usual order of development is hyperthyroidism first, then PTM, and later acropachy. Acropachy may develop up to 40 years after the initial emergence of hyperthyroidism. PTM is a skin disorder more accurately called localized myxedema. Unlike rashes, the disorder is confined to a specific dermal or skin area, without spreading.

Pretibial refers to the lower front surface area of the leg, including the skin covering the foot and shin. Although myxedema is a synonym for hypothyroidism, pretibial myxedema is not at all related to hypothyroidism. Rather, used in this sense, myxedema refers to the swollen tissue and excess mucin content. Mucin is a gelatinous substance which accumulates in the skin causing a waterlogged appearance.

Besides the pretibial area, the localized myxedema of Graves’ disease may affect the back, arms and shoulders, and recent studies indicate that it may develop in sites of scarring or trauma. One recent study describes a patient developing localized myxedema on the thigh at the site of a donor skin graft. This was the initial presentation or earliest symptoms of Graves’ disease for this patient. Hyperthyroidism developed later. (J An Acad Dermatol 1998 Nov; 39(5) Part 2:846).