Melanoma is a serious type of skin cancer that originates in the melanocytes, the cells responsible for producing the pigment melanin. This malignancy can develop in an existing mole or appear as a new, unusual growth on the skin. A common question when people notice a change in a mole is whether the sensation of itching, known medically as pruritus, is a sign of this disease. This article addresses the relationship between itching and melanoma, detailing the more common physical warning signs and explaining the biological reasons behind the sensation.
The Link Between Itching and Melanoma
Itching can indeed be a symptom of melanoma, but it is not the most frequent or definitive sign. While a lesion that itches warrants attention, the absence of itching does not rule out the possibility of melanoma. New or changing symptoms like itching or tenderness fall under the category of “Evolving,” a key warning sign.
Non-melanoma skin cancers, such as basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), are more commonly associated with itching. Any new symptom, including persistent itching, bleeding, or crusting, should prompt a medical evaluation. Any change in sensation should be considered alongside physical changes in the lesion itself.
Recognizing the Primary Warning Signs
Healthcare providers rely on the ABCDE criteria—a set of visual and structural characteristics—to identify potential melanomas. These physical changes are considered more reliable indicators than a sensory symptom like itching.
ABCDE Criteria
- Asymmetry: The two halves of the spot would not match if a line were drawn through the middle.
- Border irregularity: The edges of the lesion are often ragged, blurred, or notched, unlike the smooth borders of a typical mole.
- Color variation: Melanomas frequently display multiple colors, including different shades of black, brown, tan, red, white, or blue.
- Diameter: The lesion is usually greater than 6 millimeters (the size of a pencil eraser), though melanomas can be smaller when first detected.
- Evolving: This refers to any change in the mole over time, including changes in size, shape, color, elevation, or the development of new symptoms like bleeding, crusting, or itching.
Why Skin Lesions Become Pruritic
The sensation of itching (pruritus) in a skin lesion is typically a result of the body’s local inflammatory response. When a lesion is growing or undergoing transformation, it interacts with the surrounding tissue and immune system. This interaction triggers the release of chemical mediators, such as histamine and certain cytokines, into the upper layers of the skin.
These released chemicals irritate the sensory nerve endings located in the dermal and epidermal layers, which registers in the brain as an itch sensation. The rapid growth of malignant cells can also irritate nerve fibers within the lesion, contributing to the feeling of pruritus. Benign causes of itching might include simple friction, skin dryness, or contact with an irritant.
When to Seek Professional Evaluation
Any skin lesion that is new, changing, or symptomatic should be evaluated by a dermatologist or physician without delay. The presence of any suspicious feature, particularly one that looks different from all other moles on the body—the “Ugly Duckling” sign—is a prompt for professional assessment. Actionable symptoms that warrant an immediate visit include a mole that begins to bleed, crust over, or feel tender or painful. The presence of persistent itching localized to a single spot is also an important change to report to a healthcare provider.
During an evaluation, the provider will examine the suspicious lesion, often using a handheld magnifying tool called a dermatoscope. If the lesion meets the ABCDE criteria or is otherwise suspicious, a biopsy will be performed, which involves removing all or part of the growth for laboratory testing. Early detection dramatically increases the five-year survival rate for melanoma.