A mole (nevus) is a common skin growth consisting of clusters of melanocytes, the pigment-producing cells in the skin. Most individuals develop between 10 and 40 moles, and the majority are benign. Moles can be flat or raised, ranging in color from the skin’s natural tone to pink, tan, brown, or black.
Why Moles Appear Anywhere on the Body
The presence of a mole on a non-sun-exposed area, such as the buttocks, is considered completely normal. Moles develop when melanocytes grow in a clump instead of being evenly spread throughout the skin’s layers. This clustering is largely influenced by genetic factors and biological processes, including hormonal changes.
While sun exposure is a well-known factor that can increase the number of moles a person develops, it is not the sole cause. Many moles are acquired during childhood and adolescence, often appearing during periods of hormonal fluctuation like puberty or pregnancy. Because melanocytes exist across nearly the entire body, new moles can emerge in any location, regardless of how much sunlight that area receives.
Health Implications of Moles in Non-Sun-Exposed Areas
The location of a mole on an area like the buttocks, which receives little to no ultraviolet (UV) light, does change the assessment of its risk profile. The vast majority of melanomas are attributed to UV radiation damage and typically occur on sun-exposed skin. However, the absence of sun exposure does not make a mole immune to becoming cancerous.
Melanoma is a cancer of the pigment cells, meaning it can develop anywhere melanocytes are present, even in hidden locations. These less common melanomas that occur in non-UV-exposed areas are not caused by sun damage but rather by other factors, including genetic mutations. These growths can appear on the soles of the feet, under the nails, in the genital area, or on the trunk and buttocks.
For people with darker skin tones, the likelihood of melanoma occurring in these hidden areas is often higher than on sun-exposed sites. Therefore, a mole in a private area should not be automatically dismissed as harmless. While the overall risk of any single mole turning cancerous is low, the potential for malignancy remains a consideration for any mole on the body.
Recognizing Warning Signs and Seeking Professional Advice
Monitoring all moles for changes is an important step in skin health, and the ABCDE method serves as a simple guide for self-assessment.
- Asymmetry: One half of the mole does not match the other half.
- Border: The edges appear irregular, notched, or blurred, unlike the smooth, defined edges of a benign mole.
- Color: The mole has multiple shades of tan, brown, black, red, or white within the same lesion.
- Diameter: Melanomas are often larger than six millimeters, or about the size of a pencil eraser.
- Evolving: Any change in the mole’s size, shape, color, or elevation over time.
Because moles on the buttocks are difficult to see clearly, regular self-examination requires using a hand mirror or asking a partner for help. The most reliable way to monitor hard-to-see areas is through professional, full-body skin examinations performed by a dermatologist. Scheduling annual skin checks is a proactive measure that increases the chance of early detection for any potential issue.