Melanoma: what it is, what it looks like, and how it differs from a mole

Melanoma is a malignant tumor arising from the pigment cells of the skin, not "just another mole" that you can stare at in the mirror for years. Below: what it is, what it looks like, how it differs from a nevus, and when it's time to see a doctor.

What melanoma is and whether it is cancer

Yes, it is cancer. Melanoma is a malignant tumor arising from melanocytes, the cells that produce the pigment melanin and determine the color of skin and hair. It belongs to the group of malignant skin tumors but is considered the most dangerous and, at the same time, the rarest: it leads in mortality among skin diseases.

There is no such thing as a benign melanoma: that is sometimes what an ordinary nevus—a mole—is called; it may remain unchanged for years.

Most often the tumor arises in the skin, less often in the retina of the eye, on the mucous membranes of the mouth, vagina, or rectum. The body offers almost no resistance: the tumor progresses rapidly and metastasizes to almost all organs.

What skin melanoma looks like and how it differs from an ordinary mole

Its appearance depends on the form. Superficial spreading melanoma is the most common variant, about 70% of cases: a flat patch of irregular shape with uneven color. The nodular form begins as a raised nodule of dark blue-black or blue-red color; there is also an unpigmented form—amelanotic melanoma.

The acral lentiginous form grows on the palms, soles, and under the nails. Lentigo maligna melanoma appears on the face and other sun-damaged areas—a large flat light-brown patch with darker areas.

An ordinary mole is symmetrical, has an even border and a single color, and remains the same for years. Melanoma changes: the contour becomes uneven, the color becomes heterogeneous, and the surface may ulcerate.

Signs of melanoma and the sites where it occurs

For self-examination there is the ABCDE system.

• A — asymmetry: one half differs from the other.
• B — border: the edge is uneven.
• C — color: shades of brown, black, white, red, and blue are mixed within one lesion.
• D — diameter: usually more than 5 mm, roughly like the eraser at the end of a pencil, although it can be smaller.
• E — evolution: the mole continues to change.

Another guide is the "ugly duckling": the lesion does not resemble other spots on the body and stands out from the general background.

Warning signs include itching, loss of hair from the surface of the nevus, ulceration, growth, disappearance of the skin pattern, and bleeding. The skin is not the only site: lentiginous melanoma of the mucous membranes accounts for about 1% of all melanomas. Melanoma also occurs in children, including from congenital nevi.

Why melanoma develops: risk factors

The underlying cause is mutations in melanocytes. The leading external factor is ultraviolet radiation: solar and artificial, from tanning equipment. Burns sustained in childhood and youth play a role years later. The risk is higher with fair skin, blue or green eyes, red or blond hair, and phototypes I and II; with V and VI it is lower but not zero.

Next come numerous nevi (more than 50), dysplastic nevi, large congenital moles, a family history of melanoma, weakened immunity, ionizing radiation, and xeroderma pigmentosum. The risk increases with age and after a previous melanoma.

How melanoma is diagnosed

The doctor examines the skin and assesses the size, shape, color, and texture of the suspicious area using a dermatoscope—this is the earliest diagnostic method. The final diagnosis is made only after a histological examination: the area of skin is excised and studied under a microscope.

When melanoma is confirmed, a sentinel lymph node biopsy and CT may be performed to determine whether the tumor has spread. The prognosis depends on how early the diagnosis is made: at an early stage most melanomas are curable surgically, while with a depth of more than 4 mm or lymph node involvement the likelihood of recurrence is higher. Recurrence is possible even after years.

When to see a doctor about a changing mole

A reason for a visit is a new mole or a change in an existing one: shape, size, color, pain, swelling, inflammation, bleeding, itching. In most cases it is impossible to determine from appearance alone whether a mole is benign—that is for a doctor to decide.

A mole by itself is not a reason to call an ambulance; 103/112 — for life-threatening conditions.

This text is for reference: it does not replace an examination by a doctor and does not eliminate the need for dermatoscopy.

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