Thyroid acropachy is one of the rarer signs of Graves' disease and is usually associated with localised myxoedema. It resembles clubbing of the fingers (and toes), and the curving of the nails is most marked in the thumb and index fingers. Patchy subperiosteal new bone formation may be apparent clinically or may be visible on X-ray (Fig. 17.43) and differs from the linear new bone formation seen in hypertrophic osteoarthropathy.
