Hyperpigmentation

What is Hyperpigmentation

Disorders of hyperpigmentation are also divided into two groups - localized and diffuse. The localized forms are due to an epidermal alteration, a proliferation of melanocytes, or an increase in pigment production. This darkening occurs when an excess of melanin, the brown pigment that produces normal skin color, forms deposits in the skin. Hyperpigmentation can affect the skin color of people of any race.
Both seborrheic keratoses and acanthosis nigricans belong to the first group.

Seborrheic keratoses are common lesions, but in one clinical setting they are a sign of systemic disease, and that setting is the sudden appearance of multiple lesions, often with an inflammatory base and in association with acrochordons (skin tags) and acanthosis nigricans. This is termed the sign of Leser-Trelat and signifies an internal malignancy.

The combination - hyperpigmentation - means more color. A rash that is hyperpigmented is darker than the surrounding skin. Acanthosis nigricans can also be a reflection of an internal malignancy, most commonly of the gastrointestinal tract, and it appears as velvety hyperpigmentation, primarily in flexural areas. In the majority of patients, acanthosis nigricans is associated with obesity, but it may be a reflection of an endocrinopathy such as acromegaly, Cushing's syndrome, the Stein-Leventhal syndrome, or insulin-resistant diabetes mellitus (type A, type B, and lipoatrophic forms).