Can endocrine and metabolic disorders cause altered skin pigmentation?

Yes. Addison’s disease is the prototype disorder with diffuse hypermelanosis associated with pigment accentuation in mucous membranes, skin folds, palmar creases, and pressure points (elbows, knees, knuckles, and coccyx). Adrenocorticotropic hormone (ACTH) or melanocyte-stimulating hormone (MSH)–producing tumors can cause increased skin pigmentation. Similarly, systemic administration of ACTH and MSH may cause skin hyperpigmentation. Pregnancy and estrogen therapy can cause hyperpigmentation, usually of the nipples and anogenital skin. Additionally, a masklike hyperpigmentation, called melasma, can develop on the forehead, temples, cheeks, nose, and upper lip in pregnant women and women receiving estrogen therapy.

Patients with porphyria cutanea tarda can have profound hyperpigmentation of sun-exposed skin associated with facial hirsutism. Nutritional disorders, such kwashiorkor, pellagra, and intestinal malabsorption, can cause skin hyperpigmentation along with areas of hypopigmentation.