A mole, or nevus, is a common skin growth consisting of an accumulation of pigment-producing cells called melanocytes. These growths are typically harmless and found on nearly every adult, presenting as flesh- to brown-colored spots or nodules. While a mole itself is benign, its cells can undergo malignant transformation into melanoma, a dangerous form of skin cancer. If not detected and treated early, a cancerous mole can be deadly.
Understanding the Melanoma Link
Melanoma is a cancer originating in melanocytes, the cells responsible for producing the skin pigment melanin. This malignancy results from the uncontrolled growth of these cells. It can occur spontaneously in previously normal skin or develop within an existing mole, though only about 30% of melanomas arise from a pre-existing mole. Monitoring any pigmented lesion is important due to this potential for cellular change.
The prognosis for melanoma is highly dependent on the stage at which it is diagnosed. When detected while still localized (confined to the original site), the five-year survival rate is greater than 99%. This high survival rate emphasizes the importance of early detection efforts.
The survival statistics decline significantly once the cancer has progressed beyond the skin surface. When the malignancy has spread to nearby lymph nodes (regional or Stage III disease), the five-year survival rate drops to approximately 75%. If the melanoma has metastasized to distant organs, such as the lungs or brain, the five-year survival rate falls to around 35%.
Despite these risks, the overall five-year survival rate for all stages of melanoma combined is 94%, due to advancements in treatment and increased public awareness. This reflects how successful treatment can be when the disease is caught early. Understanding the signs of this transformation is the most effective defense against the disease.
Identifying Warning Signs
The most effective tool for self-monitoring is the ABCDE method, a set of visual guidelines that helps distinguish a benign mole from a potentially cancerous one. The first criterion, Asymmetry, refers to a lack of uniformity; if a line were drawn through the center of the lesion, the two halves would not match. Benign moles are typically symmetrical and round or oval.
Border irregularity is a significant indicator, where the edges of the spot are ragged, notched, blurred, or uneven rather than smooth and well-defined. The third sign, Color variation, means the mole contains multiple shades of color, such as different tones of brown or black, or patches of white, red, or blue. A harmless mole usually exhibits a single, uniform color.
Diameter suggests that a lesion is concerning if it is larger than six millimeters, roughly the size of a pencil eraser. However, some melanomas are found when they are smaller than this measurement. Any growth in size should be noted regardless of the current diameter.
The final sign is Evolving, which means any change in the mole’s appearance over time. This includes changes in size, shape, color, or elevation, or the development of new symptoms such as itching, tenderness, bleeding, or crusting. A mole that changes significantly or appears different from all others on the body (the “ugly duckling” sign) warrants professional examination.
Medical Evaluation and Treatment
If a mole exhibits any of the ABCDE warning signs, the next step is a professional skin examination by a dermatologist. During this check, the physician will use a handheld magnifying instrument called a dermatoscope to examine the suspicious lesion closely. For high-risk individuals with many moles, the doctor may recommend total body photography to establish a baseline for tracking future changes.
To definitively diagnose melanoma, a biopsy is performed to remove a tissue sample for laboratory analysis by a pathologist. An excisional biopsy, which removes the entire suspicious lesion along with a small margin of surrounding healthy tissue, is often preferred for smaller spots. This procedure is usually done in an outpatient setting using a local anesthetic.
If the pathologist confirms the diagnosis of melanoma, the treatment plan is determined by the cancer’s stage, particularly its thickness. For very thin, early-stage melanomas, the initial excisional biopsy may also serve as the complete treatment. Thicker or more advanced melanomas require a wider surgical removal of tissue to ensure all cancerous cells are gone.
In cases where the cancer has grown deeper or is suspected to have spread, additional procedures like a sentinel lymph node biopsy may be performed to check if cancer cells have reached the nearest lymph nodes. If the disease is confirmed to have spread regionally or distantly, treatment becomes more complex. This may involve advanced therapies such as immunotherapy, targeted therapy drugs, or chemotherapy.