An atypical mole, often called a dysplastic nevus, appears unusual but is not cancerous upon initial diagnosis. These lesions are overwhelmingly benign growths of pigment-producing cells. However, their presence signals a potential for increased risk regarding melanoma, the most serious type of skin cancer. Understanding the distinction between an atypical mole and melanoma is fundamental to proper skin care and monitoring.
Defining Atypical Moles
Atypical moles are technically known as dysplastic nevi, where “dysplastic” refers to the presence of abnormal cells within the tissue. These moles look different from common moles, which typically have a uniform color, smooth border, and are small. Dysplastic nevi often exhibit characteristics that overlap with early melanoma, making them difficult to distinguish visually.
Atypical moles are often larger than six millimeters in diameter. They frequently display irregular shapes and have edges that are blurry, ragged, or notched. Color variation is also characteristic, often including a mix of shades like pink, red, tan, and dark brown within the same lesion.
These moles can appear anywhere on the body, though they are most common on the trunk, head, and neck, and are often inherited. Although a dysplastic nevus is a benign lesion, its cells have an unusual or disordered structure under a microscope.
Understanding the Cancer Risk
While an atypical mole itself is not cancer, its existence is strongly linked to an increased risk of developing melanoma. The vast majority of atypical moles will never transform into cancer, remaining stable throughout a person’s life. Their presence indicates a higher inherent susceptibility to melanoma compared to the general population.
Melanoma is estimated to arise from an existing mole in only about 20% to 30% of cases, with the majority forming on previously clear skin. Atypical moles primarily serve as a marker of a person’s overall cancer risk. For instance, having five or more dysplastic nevi can increase the risk of developing melanoma by approximately 10 to 12 times.
The risk escalates significantly for individuals with Familial Atypical Multiple Mole Melanoma (FAMMM) syndrome, an inherited condition. People with this syndrome have numerous atypical moles and face a much higher lifetime risk of developing melanoma, requiring rigorous skin surveillance.
Medical Assessment and Follow-Up
Management revolves around vigilant monitoring for signs of change, beginning with self-examination. Patients should perform regular skin checks, ideally monthly, using the ABCDE rule to identify potentially problematic lesions. This mnemonic guides the inspection of a mole for the following characteristics:
- Asymmetry
- Border irregularity
- Color variation
- Diameter larger than six millimeters
- Evolution, which is any change in the mole over time
Professional care involves full-body skin exams performed by a dermatologist, typically once or twice a year, or more frequently for high-risk patients. Dermatologists may use a magnifying tool called a dermatoscope to examine the mole’s structure in detail. For patients with numerous or complex moles, mole mapping uses specialized photography to create a baseline record for tracking changes over time.
A biopsy is performed when a dermatologist suspects a mole might be or is becoming cancerous, or when it exhibits significant changes. The pathologist examines the tissue and classifies the degree of cellular abnormality, or atypia, as mild, moderate, or severe. Moles with mild atypia often require only clinical monitoring.
For moles classified as having moderate or severe atypia, complete surgical removal is generally recommended. A complete excision involves surgically removing the mole along with a small margin of surrounding healthy skin. This procedure minimizes the chance of recurrence or progression by ensuring that precursor cells are fully eliminated.