Hyperpigmentation is a term that refers to any darkened spot on your skin caused by the overproduction of melanin, a brown skin pigment. Hyperpigmentation is often caused by UV exposure, leaving spots of uneven skin tones like age spots and freckles. Sun-induced hyperpigmentation is usually treated topically with skin brighteners, like Hale Cosmeceuticals’ SB-7. However, some types of hyperpigmentation, such as dark spots on the neck, armpits and other skin folds, may be the result of systemic issues and do not respond effectively to topical treatment.
UV radiation from the sun (or tanning beds) is just one potential cause of hyperpigmentation. Melanocytes may also be stimulated to produce more pigment during pregnancy and as the result of some drugs.
In the case of dark spots on the neck, armpits and other skin folds, the hyperpigmentation may be a sign of acanthosis nigricans (AN).
AN is characterized by thickened, darker skin with a velvety texture in the armpits and skin folds. AN has a number of possible causes, including:
Acral acanthosis nigricans is a specific type of AN that presents mostly on joints—knees, elbows and knuckles—in otherwise healthy individuals.
Acanthosis nigricans generally does not respond to topical treatment. In other words, nothing you apply to your skin will lighten the dark spots. Instead, the underlying cause must be addressed. In the case of obesity- and drug-related AN, weight loss and drug cessation, respectively, often result in the natural lightening of dark spots (although lightening may take months or years).
Since a number of AN types are interrelated with blood glucose levels, testing and treatment for diabetes or related disorders like hyperglycemia, may be the first step to diagnosis and treatment that may result in the diminishment of dark spots.