Skin color is influenced by a person’s genetic heritage as well as environmental factors. It is determined by the amount of pigment or melanin that is produced in the skin. The cells manufacturing this pigment are called melanocytes. These cells are found throughout the upper layers of the skin. Natural pigment is nature’s way of protecting the skin from ultraviolet light. A suntan is actually sun damage and does not provide sun protection.
Uneven pigmentation of the skin may be a natural occurrence or related to ultraviolet light, infection, hormones, drugs, acne or topical chemicals applied to the skin. There are also skin diseases and genetic abnormalities that can cause hyperpigmentation. Common causes of hyperpigmentation include sunspots, freckles, “acne spots” and melasma (pregnancy mask).
Melasma is a common condition seen in women, related to hormones (estrogen) and sun exposure. This condition is frequently exacerbated during pregnancy, at menopause, and with the use of oral contraceptives. The skin darkens in patches of tan to brown, primarily on the sun-exposed areas such as the face, neck and arms. Most sun exposure throughout the day is brief but cumulative. Consequently, brief exposures without sunscreen can cause dramatic changes in skin pigmentation.
Sunspots, commonly referred to as liver spots, are a product of sun exposure. Sunspots result from the increased production of melanin as a consequence of long-standing sun exposure. The most common areas involved are the face, neck, upper chest and arms. Freckles, develop in fair-skinned individuals as a result of sun exposure. This is the skin’s protective measure against the harmful effects of ultraviolet light. Freckles are predominantly seen on sun-exposed surfaces and will fade when the skin is protected from ultraviolet light.
Medications are a frequent cause of sudden skin pigmentation. Most of the pigmentation is seen in sun-exposed areas suggesting an interaction between ultraviolet light and the ingested medication.
Finally, post-inflammatory skin darkening is a common occurrence after irritation or injury to the skin. It is more prominent in dark-skin, however, it is also seen in lighter-skin individuals. After irritation or injury to the skin, the pigment cells (melanocytes) deposit pigment in both the upper and lower layers of the skin. This is a condition that usually clears with time, although it can last for months to years. Immediate treatment is important, as this will help determine the outcome and ultimate appearance of the area.