Cancerous Mole: How a Nevus Differs from Melanoma

A dark mole that has changed over the past months requires attention: this is often how melanoma begins, the most serious type of skin cancer. The difference between a benign nevus and melanoma is not always visible, and it is determined by a doctor during examination, and definitively by tissue examination.

What a mole (nevus) is and whether a "cancerous mole" exists

A nevus is a benign accumulation of melanocytes, pigment cells that produce melanin. Melanoma, a malignant skin tumor prone to recurrence and metastasis to various organs, develops from these same cells. The expressions "cancer mole" and "cancerous mole" are used in conversation, but they describe not a separate type of formation, but a situation where a malignant tumor has arisen in the area of a mole or looks like a new mole.

Often the first sign of melanoma is a change in size, shape, color, or sensations in the area of a mole. It may also appear as a new formation — black, unusual, "ugly" in appearance. According to WHO, in 2000 more than 200,000 cases of melanoma and 65,000 melanoma-related deaths were diagnosed worldwide.

Nevus and melanoma: what the difference is

A nevus grows from melanocytes but remains benign: its cells do not extend beyond the formation. Melanoma is a malignant tumor; its cells grow deep into the skin and spread to lymph nodes and other organs. The phrase "benign melanoma" is incorrect: nevi are benign, while melanoma is malignant by nature.

Some nevi increase the risk. An atypical (dysplastic) nevus is classified as a benign neoplasm, but it is listed among melanoma risk factors — as is having more than 50 moles on the body. Among patients in whom melanoma was linked to a background lesion, there were compound (45%), junctional (34%), intradermal (16%) nevi and blue nevus (3.2%); 70% of these nevi were congenital, 30% were acquired.

Signs of malignant moles: asymmetry, borders, color, size

A mole is assessed using the ABCDE system proposed by Friedman in 1985. It helps to remember what exactly to look at:

• Asymmetry — the shape of one half does not match the other;
• Border — the edge is uneven, blurred, or jagged;
• Color — the color is uneven, with shades of black, brown, and tan;
• Diameter — diameter greater than 6 millimeters or its increase;
• Evolving — changes over the past weeks or months.

Signs of malignant transformation also include itching in the area of the nevus, hair loss from its surface, changes in outline, ulceration, bleeding, growth, and nodule formation.

Black and dark mole: what the doctor assesses

Dark color and uneven pigmentation are part of the ABCDE signs: color is assessed as uneven if the mole contains shades of black, brown, and tan. What a specific mole means is decided by the doctor during examination. The palms, fingertips, and nails deserve special attention: acral lentiginous, or subungual, melanoma develops there — about 10% of skin melanoma cases, more often in dark-skinned people.

How a mole is diagnosed and when to see a doctor

Examination begins with dermatoscopy — the earliest diagnosis of melanoma. The doctor examines the formation through a magnifying glass or dermatoscope, which makes the stratum corneum of the epidermis transparent, and assesses it using the ABCDE system. Computer microdermoscopy systems increase the level of early diagnosis from 60% to 90%, but often only in experimental settings. The final diagnosis of melanoma is established only after histological examination of tissue.

A reason to consult a doctor (dermatologist) is a mole that has changed over weeks or months, itches, bleeds, has a diameter greater than 6 millimeters, or has uneven edges. Risk factors: ultraviolet radiation, sunburns in childhood and youth, fair skin and blue eyes, family history of melanoma, age over 50 years.

A mole by itself is not a reason to call an ambulance; 103/112 — if a life-threatening condition has occurred, such as a stroke or heart attack.

This material is for reference: it describes the diagnostic pathway and questions that can be asked to a doctor, but does not replace consultation with a specialist who will examine the mole and decide what to do next.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer