Pigmentation is present in more than ninety per cent of cases; this results from increased melanin in the skin and mucous membranes, and is more readily seen in areas exposed to light or pressure. Thus, the face (Fig. 9.2), the back of the hands, elbows and knees, the buccal mucosa, conjunctivae, nails, axillae, and skin creases are commonly pigmented.
In a patient with suspected adrenocortical insufficiency, the clinical sign of pigmentation will nearly always distinguish primary adrenocortical insufficiency from that which is secondary to either hypothalamic or pituitary disease.
