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Uneven Skin Tone

As summer tans fade, we may see remnants on our skin of those happy hours spent in the sun. That is because the cells (melanocytes) that produce skin tone or pigment (melanin) are stimulated by sun exposure to produce more melanin. Excess melanin can cause visibly uneven areas of darker skin, a condition called hyperpigmentation. Conversely, other areas may lose melanin, resulting in pale or white spots, a condition called hypopigmentation. 

 

In general, most causes of uneven pigmentation are benign and resolve on their own over time. But if you notice new or persistent uneven spots or patches – either lighter or darker – it is wise to keep an eye on them. In some cases, pigmentation irregularities can be a sign of an underlying progressive skin disease that needs medical evaluation to prevent worsening.

Hypopigmentation – The Loss of Skin ColorHypopigmentation
Hypopigmentation can be caused by several common and benign conditions. Seborrheic dermatitis, for example, can produce a mild irritation that disrupts the production of melanin. Tinea versicolor, a rash caused by yeast that is most commonly seen on the chest and/or back, can virtually “turn off” melanocytes, creating white spots that do not tan. Such conditions can easily be treated, and pigmentation eventually returns to normal. While the hypopigmentation caused by such conditions is reversible, there are certain fairly common skin disorders that cause hypopigmentation that is difficult, if not impossible, to correct.

One such condition is idiopathic guttate hypomelanosis (which means “confetti-like light spots”), which occurs for no known reason. This disorder appears to run in families and may be triggered by sun exposure. The typical appearance is a random sprinkling of numerous small pale to white spots on the lower legs. It is more visible in darker skin tones because of the dramatic contrast between normal skin color and the light spots. Although the condition is completely benign and does not tend to spread to other parts of the body, it can be very frustrating for patients, as the loss of color is difficult to treat and conceal, especially in darker skin tones.

VitiligoVitiligo on the face
Similar in its difficulty to treat but of more serious nature is a condition called vitiligo. Vitiligo presents as a sudden or gradual appearance of hypopigmented patches that progress to total loss of color in the affected skin. Vitiligo can start as one or several individual light patches that can appear anywhere on the body. Vitiligo can affect all ethnic groups, and it often runs in families without a clear pattern of inheritance. Although vitiligo is a complex and often devastating disease, most people who develop hypopigmentation do not have vitiligo.  

Nonetheless, it is important to pay attention to newly developing patches of hypopigmentation that persist over the course of a month or two. If the area(s) of hypopigmentation get larger or increase in number, see a dermatologist for evaluation. Vitiligo can only be definitively diagnosed through special skin testing conducted by dermatologists.

While the exact cause of vitiligo is unknown, it can often be associated with autoimmune disease, where the body starts to view the color cells as “foreign invader” cells and signals the immune system to destroy them. Vitiligo can be linked with other systemic diseases that involve the immune system such as pernicious anemia, thyroid disease, or even HIV. A complete medical evaluation is recommended when a person develops suspicious hypopigmentation, not only to check for systemic diseases, but to also rule out the presence of other skin diseases.

Besides possible systemic disease that may exist with vitiligo, the often-dramatic changes in outward appearance require medical treatment. The goal in most cases is to return normal color to the skin – a process called repigmentation – and some notable advances in treating the disease have been made in the past decade. These include topical steroids and steroid-sparing creams, light therapies, and excimer laser therapies. Typically, patients are treated with a combination of therapies with results ranging from minimal to exceptional repigmentation, depending on the type of vitiligo and the length of time it has been present. All of the therapies take months to work, and the earlier the treatment is started, the better the expected results.

Vitiligo, Cosmetic Therapies, and Sun Exposure
I want to add two cautionary notes involving cosmetic therapies and sun exposure. As a laser surgeon, I recommend that those with a family history of vitiligo discuss this with their doctor prior to undergoing laser therapy for any type of skin rejuvenation. While most such laser therapies are extremely safe and effective methods of decreasing wrinkles and sun damage when performed by skilled physicians, they can potentially increase the risk of developing vitiligo in someone predisposed to the condition. 

Lastly, no mater what the ethnicity or natural complexion of the vitiligo patient, vitiligo patches are extremely vulnerable to damage from UV light. Therefore, consistent use of sunscreen and other sun-protective measures are of the utmost importance.

Hypopigmentation and Scarring
Another cause of hypopigmentation is that due to scarring. When a wound occurs that penetrates deep into the skin, it can cause a scar that is lighter than the normal surrounding skin color. Melanin is produced in one of the top layers of skin, so when skin is injured below that level, it starts to heal without the normal reproduction of melanin. Fortunately, the hypopigmentation caused by scarring often reverses with time and can be assisted with certain medical therapies.

Hyperpigmentation – an Increase in Skin ColorHyperpigmentation on the neck
While hypopigmented scarring is not uncommon, the vast majority of scarring is hyperpigmented in nature. Hyperpigmentation, on the opposite side of the pigmentation spectrum from hypopigmentation, is an increase above one’s normal baseline color, causing dark spots, patches, or scars.

Hyperpigmentation can be caused by a variety of common conditions, like bug bites, acne, melasma, eczema, sun damage, or skin cancer. In addition, it may signal the presence of other diseases including but not limited to certain types of lupus, a reaction to oral or topical medications, endocrine abnormalities, and nutritional disorders. While hyperpigmentation can occur in all skin tones, it occurs more commonly (and looks more prominent) in richer skin tones.

Post-Inflammatory Hyperpigmentation
The most common cause of hyperpigmentation in darker skin tones is post-inflammatory hyperpigmentation (PIH), which is simply darkening of the skin after the occurrence of any type of inflammation or irritation. Acne, eczema, and even bug bites are often the source of this skin inflammation and irritation. Patients who exhibit PIH, as well as other hyperpigmentation disorders, can be treated with excellent results by physicians who have experience in treating skin of color with laser therapies. However, just like with hypopigmentation, the longer the hyperpigmentation has been present, the more difficult it is to restore the skin to its normal color. 

While people with lighter skin tones are typically spared the effects of PIH, they are not spared hyperpigmentation that results from underlying endocrine disease, nutritional disorders, and reactions to oral and topical medications. In addition, lighter skin is more susceptible to hyperpigmentation due to sun damage.

Hyperpigmentation and Sun DamagePoikiloderma of Civatte
One common presentation of sun damage in lighter skin tones is a condition called poikiloderma of Civatte. It is largely seen on the sides of the neck and chest in middle-aged or older fair-skinned women. It is caused by UV exposure and begins as a dark bronze or red flush. With increased or regular sun exposure, the skin becomes mottled and leathery, and the elastin breaks down. As the condition progresses, silvery patches and hypopigmentation may develop. Most women will recognize this condition, either on themselves or others. In order to help prevent it, I recommend that my patients use sunscreen on the neck and chest as well as the face. Fortunately, it can be treated with very nice results with the right combination of topical and laser therapies.

As we enter into the cooler months, when we typically lose our tans and see the effects of the sun on our skin, it is important to take note of any changes in skin color that do not resolve. If you observe either hypopigmentation or hyperpigmentation that persists or enlarges, it is best to see a dermatologist to help determine the root cause. Remember, no matter what the cause, the longer the change has been present, the harder it will be to treat it successfully. With prompt and proper diagnosis and treatment, skin color can often return to normal.

 

 

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