A mole, medically known as a nevus, is a common growth on the skin that typically appears as a small, dark spot. These growths form when pigment-producing cells, called melanocytes, grow in clusters. While most moles are brown or black due to melanin, some moles can appear white, or lose their characteristic color over time. A white mole, or a mole that has become depigmented, can sometimes prompt questions or concerns for individuals observing changes on their skin.
Understanding Moles and Hypopigmentation
Moles derive their color from melanin, a pigment produced by specialized cells known as melanocytes, which are found in the skin. The amount and type of melanin determine the mole’s shade, ranging from light tan to dark brown or black. These melanocytes are typically abundant and active within the mole, contributing to its distinct appearance.
When a mole appears white, it indicates a lack or reduction of melanin, a condition referred to as hypopigmentation. This can occur either within the mole itself or in the surrounding skin. Several biological mechanisms can lead to this loss of pigment, affecting the melanocytes’ ability to produce melanin or causing their destruction.
Common Reasons for a White Mole
One common reason for a mole to appear white is a condition known as a halo nevus. This type of mole is characterized by a white ring or halo of depigmented skin that forms around an existing pigmented mole. The immune system targets the melanocytes within the mole and the surrounding skin, causing them to lose pigment. Eventually, the central mole often fades away completely, leaving only the white patch.
Another possibility is nevus depigmentosus, a congenital birthmark characterized by a patch of skin that is lighter than the surrounding skin. Unlike a typical mole, nevus depigmentosus is not caused by a cluster of melanocytes but rather by a localized reduction in melanin production or melanocyte function. It is generally stable and does not change over time.
Vitiligo, an autoimmune condition that causes patches of skin to lose pigment, can also affect moles. If vitiligo develops on an area of skin where a mole is present, the mole itself may become depigmented, or the surrounding skin may turn white. This occurs when the immune system attacks and destroys melanocytes in the affected areas.
Post-inflammatory hypopigmentation can cause a mole or the skin around it to appear lighter after an injury, infection, or inflammatory skin condition. For example, a mole might lose pigment after being scratched or experiencing an allergic reaction. This loss of color can be temporary or persist indefinitely.
Scar tissue can also present as a white area on the skin, and sometimes a mole might be located within or adjacent to a scar. Scars form from damaged skin, and scar tissue lacks the melanocytes necessary to produce pigment, resulting in a lighter appearance. If a mole was injured or removed and replaced by a scar, the resulting white area might be mistaken for a white mole.
When to Consult a Doctor
While many white moles are benign, certain changes warrant a medical evaluation. Consult a doctor if a white mole, or any mole, undergoes noticeable changes. This includes changes in size, especially rapid growth, or alterations in shape, such as developing irregular or asymmetrical borders.
Changes in color are also significant, including new whiteness within a previously pigmented mole or uneven pigmentation with multiple shades. Any symptoms like itching, bleeding, or pain associated with the mole should prompt a professional assessment. These signs indicate underlying issues requiring medical attention.
Differentiating White Moles from Other Skin Spots
It is important to distinguish between a true hypopigmented mole and other common white spots on the skin. For example, idiopathic guttate hypomelanosis (IGH) presents as small, round, white spots, typically on sun-exposed areas like the arms and legs. These spots are benign and result from chronic sun exposure and aging, not related to moles.
Tinea versicolor, a common fungal infection, can also cause patches of skin to become lighter or darker. These patches often have fine scales and may be more noticeable after sun exposure, as the affected areas do not tan. Unlike moles, tinea versicolor patches are caused by an overgrowth of yeast on the skin’s surface and can be treated with antifungal medications. Occasionally, naturally lighter areas of skin or birthmarks that are simply hypopigmented can also be confused with a white mole.