Final answer:
Hyperpigmentation of the skin is a characteristic sign of Addison's disease, causing the skin to have a deep bronze color.
Step-by-step explanation:
Hyperpigmentation of the skin is a characteristic sign of Addison's disease. Patients with Addison's disease may have patchy skin color, which is usually a deep bronze color. This is caused by the release of excess amounts of adrenocorticotropic hormone (ACTH), which stimulates the production of melanin in the skin.