Melanoma often first appears as a new or changing spot on the skin. The classic warning signs follow a pattern doctors call the ABCDE rule, but melanoma can also show up in places you might not expect, including under your nails, on the soles of your feet, or even inside the mouth. Catching it early matters enormously: the five-year survival rate for melanoma that hasn’t spread beyond the skin is nearly 100%, but that drops to 34% once it reaches distant organs.
The ABCDE Rule for Spotting Melanoma
Most melanomas on the skin share a set of visual features that distinguish them from ordinary moles. The American Academy of Dermatology uses five criteria to help you evaluate any spot that catches your attention.
- Asymmetry. One half of the spot doesn’t match the other. A normal mole is typically round and symmetrical.
- Border. The edges are irregular, scalloped, ragged, or blurred rather than smooth. Pigment may seem to bleed into the surrounding skin.
- Color. The spot contains uneven coloring. You might see shades of brown, black, and tan mixed together, or patches of white, gray, red, pink, or blue within the same lesion.
- Diameter. Most melanomas are larger than 6 millimeters when diagnosed, roughly the size of a pencil eraser. They can be smaller, though, so size alone doesn’t rule anything out.
- Evolving. The spot has changed in size, shape, or color over the past few weeks or months, or it looks noticeably different from the rest of your moles.
Any single one of these features is worth noting. A spot that checks two or more boxes deserves prompt attention from a dermatologist. Many people find it helpful to photograph moles every few months so that subtle changes are easier to notice over time.
Nodular Melanoma Looks Different
Not every melanoma follows the ABCDE pattern. Nodular melanoma is a fast-growing type that typically appears as a firm, dome-shaped bump on the skin. It’s usually hard to the touch and can look like a blood blister. Unlike the flat, spreading shape of more common melanomas, nodular melanoma grows outward from the skin surface and can develop rapidly over just a few weeks. Because it doesn’t always display the irregular borders or mixed colors people are told to watch for, it’s easier to dismiss as harmless.
Melanoma Under the Nails
Subungual melanoma shows up beneath a fingernail or toenail, most often as a dark vertical streak running from the base of the nail to the tip. It can look as though someone drew a line on the nail with a brown or black marker. Over time, the streak may widen, become irregularly shaped, or cover the entire nail. In more advanced cases, the nail can crack or break.
One important warning sign is called the Hutchinson sign: pigment that spreads from under the nail into the surrounding skin at the cuticle. This discoloration of the skin around the nail strongly suggests melanoma rather than a benign cause like a bruise or fungal infection.
Melanoma on Palms and Soles
Acral lentiginous melanoma develops on the palms of the hands or soles of the feet. It first appears as a brown or black discoloration that may look like a bruise or a stain. Unlike a bruise, it doesn’t fade over days. Instead, it gradually grows in size. This type accounts for a higher proportion of melanoma diagnoses in people with darker skin tones, partly because other forms of melanoma (which favor sun-exposed areas) are less common in that group.
Melanoma Without Dark Color
Amelanotic melanoma produces little or no pigment, which makes it one of the most commonly missed forms. Instead of appearing dark brown or black, these lesions are often pink, red, or skin-colored. An early amelanotic melanoma might look like a flat pinkish patch with slightly irregular borders, or it may have just a faint trace of tan or gray at its edges. Because of its appearance, it’s frequently mistaken for other skin conditions, including non-melanoma skin cancers, age spots, or even a small scar. If you have a pinkish or reddish spot that isn’t healing or is slowly growing, it’s worth having it examined.
Melanoma on Mucous Membranes
Mucosal melanoma is rare but particularly tricky because it develops on the moist linings inside the body rather than on the skin. Symptoms depend entirely on location.
In the mouth, it can appear as a lump on the tongue or a sore that won’t heal, sometimes with unexplained bleeding or mouth pain. In the nasal passages, repeated nosebleeds from one nostril, a persistent feeling that something is stuck in the nose, or facial pain are common signs. In the throat, hoarseness, difficulty swallowing, or a lump on the outside of the neck may develop.
Mucosal melanoma also occurs in the anorectal area, where it can cause rectal pain, a noticeable lump, bleeding, or persistent itching. In the vulva or vagina, signs include unexplained bleeding between periods or after menopause, unusual discharge, a new growth, or itching that doesn’t respond to typical treatments. Because these symptoms overlap with many other conditions, mucosal melanoma is often diagnosed at a later stage.
Symptoms When Melanoma Spreads
When melanoma advances beyond the original site, symptoms shift from skin changes to broader, systemic problems. The specific signs depend on where the cancer has traveled.
Swollen or hard lymph nodes are often the first sign of spread. You might notice a firm lump in your armpit, groin, or neck. Swollen lymph nodes in the neck can make swallowing difficult. When cancer cells block lymph drainage, fluid can collect in the arm, leg, or face on the same side as the affected nodes.
If melanoma reaches the lungs, you may develop a persistent cough, shortness of breath, or cough up small amounts of blood. Spread to the liver can cause discomfort or pain on the right side of the abdomen, nausea, poor appetite, weight loss, yellowing of the skin, or itching. When it reaches the bones, the most common complaint is a deep, continuous, gnawing pain. Bones weakened by cancer fracture more easily, and cancer in the spinal bones can press on the spinal cord, potentially causing leg weakness, numbness, or loss of bladder and bowel control if untreated.
General symptoms like unexplained weight loss, persistent fatigue, and feeling unwell without a clear cause can also accompany advanced melanoma regardless of where it has spread.
How to Check Your Own Skin
Monthly self-exams are the most widely recommended approach. Stand in front of a full-length mirror in a well-lit room and work systematically: face, scalp (use a handheld mirror or ask someone to help), ears, neck, chest, abdomen, arms, hands (including between the fingers and under the nails), legs, feet (including the soles and between the toes), back, and buttocks. You’re looking for any new spot, any mole that has changed, any sore that won’t heal, or any growth that looks different from everything else on your skin.
Pay extra attention to areas that are easy to overlook. The scalp, the spaces between toes, the soles of the feet, and under the nails are all spots where melanoma can hide for months before being noticed. Taking photos with consistent lighting each month makes it much easier to spot gradual changes that you’d otherwise forget.