Carotenoderma

Causes

Hypercarotenemia, and the skin discoloration it causes called carotenoderma, has three main causes: eating too many carotenoids, having high lipid levels in the blood, or a reduced ability to metabolize these compounds. The most common trigger is a high intake from food or supplements, which takes four to seven weeks to show up on the skin.

High blood lipids raise carotenoid levels because the pigments travel attached to lipoproteins. Certain illnesses can slow the conversion of carotenoids to retinol, leading to their buildup. Carotenoderma is classified as primary, from excess dietary intake, or secondary, from an underlying disease despite normal intake; both forms can occur together.

Physiology

Carotenoderma occurs when carotenoids build up in the skin's outer layer, especially where it is thick or sweaty, like the palms, soles, knees, and nasolabial folds, though the color change can spread. Unlike jaundice, it leaves the whites of the eyes untouched. The condition is more noticeable under artificial light. A related condition, lycopenemia, uniquely causes a discolored soft palate and carotenoid buildup in the liver.

Secondary carotenoderma

Disease states associated with carotenoderma include hypothyroidism, diabetes mellitus, anorexia nervosa, nephrotic syndrome, and liver disease. In hypothyroidism and diabetes mellitus, the mechanism involves impaired conversion of beta-carotene into retinol and increased serum lipids; diabetes mellitus may also involve diets rich in vegetables. Nephrotic syndrome causes hypercarotenemia through increased serum lipids. Kidney dysfunction in general leads to hypercarotenemia from decreased excretion, while liver dysfunction causes it from impaired conversion of carotenoids to retinol; jaundice and carotenoderma can coexist.

Anorexia nervosa causes carotenoderma mainly through carotenoid-rich diets and associated hypothyroidism, and is more common in the restricting subtype, with other dermatologic manifestations such as brittle hair and nails, lanugo-like body hair, and xerosis. Alzheimer's disease has been associated with carotenoderma in some reports, but most studies show depressed carotenoid and retinol levels, and a true association is unclear. Case reports describe a genetic defect in carotenoid metabolic enzymes causing unresponsive carotenoderma.

Canthaxanthin and astaxanthin are used as food colorings; canthaxanthin has been used in over-the-counter tanning pills but is not FDA-approved due to adverse effects including hepatitis, urticaria, aplastic anemia, and retinopathy with yellow deposits and visual field defects.

Diagnosis

Hyperbilirubinemia is the main differential diagnosis when evaluating jaundice suspected to be carotenemia. Excessive consumption of lycopene can cause a deep orange discoloration of the skin, and like carotenoderma, lycopenemia is harmless. Excessive consumption of silver or gold compounds can cause irreversible skin discoloration (argyria or chrysiasis), unlike carotenosis.

Did You Know?

• Carotenoids contribute to normal-appearing human skin color and are a significant component of physiologic ultraviolet photoprotection.
• Infants with carotenoderma should not be taken off prescribed vitamin supplements unless advised by the child's pediatrician.