What is the typical presentation of Addison's disease in terms of skin appearance?

Addison's disease is characterized by adrenal insufficiency, which leads to a deficiency in cortisol production. One of the notable features of Addison's disease is hyperpigmentation of the skin. This occurs because low cortisol levels stimulate the production of adrenocorticotropic hormone (ACTH) from the pituitary gland, which in turn increases the production of melanin by melanocytes, leading to a darkening of the skin.

Patients may exhibit hyperpigmentation in various areas, including skin folds, scars, and mucous membranes. This symptom is often quite striking and can help in diagnosing the condition. The presence of hyperpigmentation is particularly significant because it differentiates Addison's disease from other causes of adrenal insufficiency, where hyperpigmentation may not be as pronounced or may not occur at all.

In contrast, pallor, flushing, and jaundice are not associated with Addison's disease. Pallor reflects a lack of blood flow or oxygenation, flushing indicates increased blood flow or vascular congestion, and jaundice results from elevated bilirubin levels due to liver dysfunction or hemolysis, none of which are characteristic features of Addison's disease.