Irregular areas in which there are changes in skin color are a common problem with a wide array of potential causes. You may have changes in the pigmentation of a certain area of your skin due to a difference in the level of melanin it contains. Melanin is the substance that provides color to the skin and protects it from the sun.
An infection or inflammatory problem can cause skin color changes. Also, mottled skin can be caused by changes in blood vessels under the skin. These changes can be genetic, caused by injury, or simply due to changes in hormone levels.
How Are Discolored Skin Patches Evaluated?
You should see your doctor if you have any lasting changes in your skin color. Also see your doctor if you notice a new mole or growth on your skin, or if an existing mole or growth has changed in size or appearance. Your doctor will ask you a series of questions about your skin changes and may order tests to determine why your skin has irregular coloring.
You may be asked about your normal skin color, when you first noticed the skin color change, and whether the change happened slowly or quickly. Is the change getting progressively worse? Where are the patches of changed skin located? How are they distributed on your body?
Sunburns, other burns, and other skin injuries are also important to discuss with your doctor. Similarly, it’s important to tell him or her if you are pregnant or taking any hormone treatments. All these factors may play a role in your skin changes.
Your doctor may want to sample (biopsy) a small section of the affected skin to examine under a microscope for the presence of cancerous cells. Your doctor may also look at your skin under an ultraviolent light called a Wood’s lamp to more closely examine skin color changes, or to check for the presence of bacteria. Blood tests may be necessary to check for conditions that cause a change in skin color, such as hemochromatosis (a genetic disease that results in too much iron in the body).
It is important to tell your doctor about any other symptoms you are experiencing along with patchy skin color.
What Causes Discoloration of Skin?
There are many potential causes of patchy skin color, ranging from simple to complex.
You can damage your skin with sunburn or another kind of burn, and the burn may heal with scar tissue that is a different color. You may have applied sunscreen in an incomplete manner, leading to differently tanned parts of your skin. Medications can make your skin more sensitive to the sun and more likely to turn red or burn. Radiation therapy may also cause a kind of burn and change the color of your skin.
Infections can cause localized changes in skin color. Cuts and scrapes can develop infections that turn the surrounding skin red or white and change the texture of the skin. Erythrasma is a chronic skin infection caused by bacteria that causes pink skin with brownish flaky patches and wrinkling.
Tinea versicolor and ringworm are infections caused by different types of fungi. These fungal infections can cause patches of skin to turn white, pink, tan, or brown and scaly. The patches can occur all over the body, depending on the exact type of fungus.
Autoimmune Diseases and Allergies
Autoimmune diseases, such as lupus erythematosus and dermatomyositis, can also cause changes in skin color. Eczema is a type of hypersensitivity reaction (allergy) that can cause red, scaly patches that ooze. Related to eczema, pityriasis alba can cause dry, white patches on the skin in children.
A wide variety of rashes, such as dermatitis herpetiformis, contact dermatitis, poison ivy rashes, and others can be caused by an allergic reaction. Scleroderma can create thick, shiny patches of skin. Vitiligo is a condition in which cells that produce melanin are attacked by the immune system, leaving behind patches of skin with no color at all.
Hormonal changes, especially during pregnancy, can cause skin color changes. Melasma, or chloasma, can cause dark patches on the face, often called the “mask of pregnancy.”
Birthmarks are also a cause of skin color changes. Café-au-lait spots are light-colored spots on the skin. A few café-au-lait spots are perfectly normal, but more than six may be an indicator of neurofibromatosis—a genetic disorder that negatively affects the growth and formation of nerve cells.
Moles are brown spots that can appear on the skin at birth. Changes in the size or shape of these spots can signal trouble, and should be checked by your doctor.
Mongolian blue spots are bluish patches that can appear on the backs of babies and young children, usually of Asian descent. They are harmless and often fade over time.
Port-wine stains are a type of birthmark caused by swollen blood vessels. They are usually flat and appear pink or red in color.
Cancer can change skin color or texture, and any moles or other rapidly changing skin lesions should be examined by a doctor.
What Is the Long-Term Outlook for Discolored Skin Patches?
Many skin changes are harmless. Some, such as a small infection, require only simple treatment. Other causes may be more severe and require ongoing treatment. Skin cancer is very serious and may require surgery and chemotherapy to treat. It is important to check with your doctor if you notice rapid or bothersome texture or color changes in your skin.