Hyperpigmentation due to ACTH excess

Right hand of a 16-year-old female with Nelson syndrome (right) next to that of a female without endocrine disease (left), demonstrating skin hyperpigmentation that is accentuated over the knuckles (which are areas of repeated trauma). Similar hyperpigmentation occurs in patients with other causes of chronic ACTH excess, such as Cushing's disease or primary adrenal insufficiency.