Moles are common skin growths, but a purple hue can prompt questions. This unique coloration often leads individuals to wonder if it indicates a normal variant or a potential health concern. Understanding the reasons for a mole’s purple appearance and recognizing specific characteristics helps distinguish between benign findings and those that may warrant medical evaluation.
What Gives Moles a Purple Appearance?
The purple color in certain moles results from the presence of blood vessels close to the skin’s surface or the depth and concentration of melanin. Moles with a vascular component, such as hemangiomas or venous lakes, often exhibit a reddish-purple or bluish-purple tint due to visible blood within these structures. Hemoglobin in deoxygenated blood absorbs light differently, leading to a blue or purple appearance when seen through the skin.
The depth of melanin pigment within the skin layers also influences a mole’s perceived color. Melanin located deeper in the dermis, rather than superficial in the epidermis, can scatter light, making the mole appear blue or purplish. This optical phenomenon, known as the Tyndall effect, is similar to how the sky appears blue; shorter blue light wavelengths are scattered more effectively. The combination of vascularity and deeply situated melanin are key factors in determining a mole’s purple coloration.
Common Benign Purple Moles
Many purple moles are harmless and represent common benign skin growths. Venous lakes, for instance, are soft, compressible dark blue to purple lesions found on sun-exposed areas like the lips or ears. These are dilated venules that accumulate blood, giving them their characteristic color. They are usually asymptomatic and do not require treatment unless for cosmetic reasons.
Another common type is a cherry angioma, which appears as a small, bright red to purple bump on the skin. These are benign proliferations of capillaries, and their color comes directly from the blood within these densely packed vessels. While they can range in color, a darker, more purple shade may indicate a larger or more mature angioma. Blue nevi also present as blue-grey to blue-black macules or papules, with some appearing distinctly purple. Their color is attributed to deeply situated melanocytes, which scatter blue light due to the Tyndall effect.
When a Purple Mole May Be a Concern
While many purple moles are benign, certain characteristics can indicate a need for medical evaluation, particularly concerning for melanoma. Melanoma, a serious skin cancer, can sometimes present with a bluish or purplish discoloration, especially nodular melanoma. This variant often grows rapidly and can be uniformly dark, including shades of blue, black, or purple. Its color can stem from a combination of deep melanin and increased vascularity.
The “ABCDE” rule provides a guide for identifying potentially problematic moles:
Asymmetry: One half of the mole does not match the other.
Border irregularity: Ragged, notched, or blurred edges.
Color variation: Different shades of brown, black, or even red, white, or blue within the same mole; a new purple or blue tint in an existing mole can be a concerning change.
Diameter: Greater than 6 millimeters, roughly the size of a pencil eraser, also warrants attention.
Evolving: Changes in size, shape, color, elevation, or any new symptoms like bleeding, itching, or crusting, are significant red flags.
What to Do About a Purple Mole
If you discover a purple mole, self-monitoring is a sensible initial step, but professional evaluation is often recommended. Regularly examine your skin for new moles or changes to existing ones, paying close attention to the ABCDE criteria. Taking photographs can help track subtle changes over time. If a mole exhibits concerning features, such as rapid growth, irregular borders, new purple hues, itching, or bleeding, it should be promptly assessed by a dermatologist.
A dermatologist can perform a thorough skin examination and, if necessary, a dermoscopy, which uses a specialized magnifying device to view the mole’s structure more clearly. If suspicion remains, a biopsy may be performed to remove a tissue sample for microscopic analysis. Early detection of skin cancer, including melanoma, significantly improves treatment outcomes. Any doubt about a purple mole’s nature should prompt a visit to a healthcare professional for accurate diagnosis and management.