Since there are no general screening guidelines for skin cancer, most people need to rely on recognizing the signs and symptoms of the disease to catch it as early as possible. Squamous cell carcinomas may produce a skin lesion that is wart-like and scaly, with a depression (ulcer) in the center. Basal cell cancers are often white, pearly, or flesh-colored, dome-like lumps with a waxy appearance. Signs of a melanoma often include a new or existing mole that has irregular borders or elevation, varies in color, or is changing in other ways. Complications of skin cancer, such as metastases, may lead to symptoms as well.

Skin cancers occur most commonly on sun-exposed regions of the body but may occur anywhere.

Let's take a look at the common and uncommon signs of skin cancer, as well as the specific characteristics to watch for that could signal a melanoma.

© Verywell, 2018

An Abnormal "Spot" on the Skin

Any new spots that appear on the skin could potentially be a skin cancer, considering that one in five people will develop at least one skin cancer in their lifetime. It can be difficult to distinguish the different types of skin cancer without a microscope, but the general characteristics of these tumors differ to some degree.﻿﻿

What to Look For

Basal cell carcinomas are often shiny and have been described as "pearlescent." They may be flat, raised, or dome-shaped, and are often pink, pale, or flesh-colored. On careful inspection, tiny blood vessels may be visible when compared with the surrounding skin.

This photo contains content that some people may find graphic or disturbing. See Photo Basal cell carcinoma affecting the ear. DermNet / CC BY-NC-ND

Squamous cell carcinomas are often raised and feel crusty to touch. They can appear scaly and may be ulcerated—that is, have a central depression that is lighter and flatter than the surrounding area. These cancers sometimes bleed, ooze, or form scabs.

This photo contains content that some people may find graphic or disturbing. See Photo Squamuos cell carcinoma. DermNet / CC BY-NC-ND

Melanoma commonly presents as a change in an existing mole, or a new, abnormal appearing mole (more below).

This photo contains content that some people may find graphic or disturbing. See Photo Melanoma. DermNet / CC BY-NC-ND

Frequent Symptoms (All Types)

Below are some of the symptoms of skin cancer, but it's important to recognize that each person and every skin cancer is different. If you have a spot on your skin that concerns you, it's important to have it checked out, whether or not you have any of the symptoms mentioned.

A Sore That Doesn't Heal

Many skin cancers are first dismissed as being due to a bug bite, minor injury to the skin, or irritation, but become more obvious when they don't go away over time. If you notice a sore on your skin that refuses to heal, even if it seems to be healing but then reappears, talk to your doctor. In general, any skin change that hasn't resolved on its own over a period of two weeks should be evaluated.

Changes in an Existing Skin Lesion

Some skin cancers arise out of a skin lesion or mole that has been present for a long time.﻿﻿ If you have any freckles, moles, or other skin spots that are changing, talk to your doctor.

Sensation in a Skin Lesion

Most often, we don't have any sensation associated with moles or other skin lesions. With skin cancer, people may notice persistent itching, tenderness, numbness, tingling, or pain. Some people have described the sensation as a feeling akin to ants crawling on their skin.

Melanoma Symptoms

It's important to take a closer look at the potential symptoms of a melanoma specifically, as these cancers can grow and spread rapidly, and are much easier to treat in the early stages of the disease.

A melanoma may present as a new, often abnormal appearing mole, but often arise out of moles that have been present for a long time.

In white people, and lighter-skinned Hispanics, they are most common on the legs in women and on the back in men. For those with dark skin, the most common locations are the soles of the feet, the palms of the hand, under toenails and fingernails, and on mucous membranes (such as around the mouth, nose, and genitals).

The ABCDE (and F) rule can be helpful as you check out the moles on your body:﻿﻿

A: Asymmetry

Normal freckles, moles, and other skin lesions are most often symmetric, whereas melanomas are often asymmetric. If you were to divide the mole into two halves, the two sides would appear different. Not all normal skin spots, such as birthmarks, are symmetric, however, and there are many factors that dermatologists take into account when looking at a mole.

B: Border

The borders (edges) of a melanoma are often irregular and may appear ragged, notched, or blurry. The lesion may also look like it is spreading, with redness or swelling in the area surrounding the mole or darker pigment that appears to be leaking into surrounding tissue from the border of a mole.

C: Color

Melanomas often have multiple and uneven colors and hues. These may include shades of black, brown, and tan, with areas of white, gray, red, and blue seen at times as well. Some melanomas have the classic description of being red, white, and blue, with hints of each of these colors in a single mole.

It's important to note that a mole that appears lighter in one area may be just as concerning as one that appears to be darkening in one.

D: Diameter

The diameter of a melanoma is often larger than six millimeters (1/4 of an inch), or about the size of a pencil eraser (or larger). Skin lesions that are this size should be checked out even if they are symmetrical with only one color and regular borders. Lesions smaller than an eraser should also be checked out if they have any of the other characteristics listed here.

E: Evolving and/or Elevated

"E" stands for two different features of melanoma. Moles are often elevated above the skin, often unevenly so with some parts raised and others flat. A mole that is changing (evolving) is also concerning and, in retrospect, many people with melanomas note that a mole had been changing in terms of size, shape, color, or general appearance before they were diagnosed.

When a melanoma develops in an existing mole, the texture may change and become hard, lumpy, or scaly. Although the skin may feel different and itch, ooze, or bleed, a melanoma does not usually cause pain.

F: "Funny Looking"

Sometimes, the letter "F" is added to the mnemonic and refers to a lesion being "funny looking."﻿﻿ A mole that doesn't look like other moles on your body or that simply doesn't look right to you should be checked out. You know your skin better than anyone. Trust your intuition.

Uncommon Symptoms

Other symptoms of skin cancer may also occur. While the following are uncommon, when added together, they aren't all that rare.

Change in Vision

A change in vision, such as blurry vision in only one eye, may be a symptom of ocular melanoma or melanoma of the eye.﻿﻿

Ocular melanoma accounts for around 5 percent of melanomas and occurs in the iris (the white of the eye), ciliary body, or choroid.﻿﻿

Other symptoms can include the appearance of a dark spot on the white of the eye, a loss of peripheral vision, seeing flashing lights, floaters (seeing specks floating in your line of vision), or redness or bulging of one eye.

Dark Lines on the Fingernails or Toenails

The appearance of a dark area under a fingernail or toenail that appears without an obvious injury should always be investigated. Melanoma of the nail bed (subungual melanoma) often presents when a pigmented streak of the nail involves the cuticle (Hutchinson's sign). These cancers are most common on the thumb and big toe but may occur on any nail.﻿﻿

While subungual melanomas are uncommon in whites, accounting for only around 1 percent of melanomas, they are the most common form of melanoma found in dark-skinned individuals.﻿﻿

New "Scars"

We often think of skin cancers as being bumps, but some are flat and others even present as depressions in the skin. Morpheaform basal cell carcinoma often presents as a depression of the skin that looks like a scar.﻿﻿

Flat Red Patches and Rashes

One type of cancer that affects the skin, T-cell lymphoma, often begins with very itchy, flat, red patches and plaques that are easily mistaken for eczema or psoriasis. One type of T-cell lymphoma, mycosis fungoids, transitions from these patches to dome-shaped nodules, and then to extensive reddened areas on multiple areas of the body. It may spread to lymph nodes and other regions of the body such as the lungs, liver, and bones. T-cell lymphomas most often begin on the buttocks, groin, hips, armpits, and chest.

Other cancers, such as breast cancer, may spread (metastasize) to the skin and initially be mistaken for a benign rash. Inflammatory breast cancer is a type of breast cancer that originates in the skin and appears, at first, to be an eczematous type of rash.

Complications

There are a number of complications that may occur with skin cancer. With non-melanoma skin cancers, most of these are due to the local growth of the tumor. With melanoma, complications may be related to the local growth of cancer, metastases to other parts of the body, and side effects of the treatment options used. Possible complications include:

Secondary Infection

Since skin cancer disrupts the normal protective barrier of the skin, bacteria may enter causing a skin infection. Infections can range from a mild, pimple-like infection to cellulitis (an infection that spreads on the surface of the skin but also goes deeper), and even to serious staph infections and sepsis (body wide infections). Treatments for skin cancer may likewise lead to infections.

Scarring and/or Disfigurement

Scarring and disfigurement may occur due to the growth of a skin cancer alone or due to treatments to remove it. When skin cancers are discovered early, these complications are uncommon, but cancers that have been present for some time may invade deeper into the tissues, damaging nerves or muscles.

Lymphedema

Lymphedema is a condition in which fluid builds up in a part of the body due to damage to lymph nodes and lymphatic vessels. Lymph vessels work by collecting free fluid in tissues and delivering the fluid back to veins. When damage occurs to lymph nodes and vessels, the subsequent build-up of fluid can cause swelling and tightness of the skin.

Many people are familiar with arm lymphedema that develops in some women who have had breast cancer surgery, but lymphedema may occur nearly anywhere. With skin cancer, it's most common when lymph nodes are removed as part of the surgery but may occur due to the cancer alone.﻿﻿

Recurrence

Just as cancers such as breast cancer may recur after treatment, skin cancers may recur as well, especially those that are more advanced at the time of diagnosis. Non-melanoma skin cancers may recur locally (in the area where they originated), but melanomas and some squamous cell carcinomas may recur at a distant site.

Metastases

Metastases are uncommon with basal cell cancers or early-stage squamous cell cancers. More advanced squamous cell cancers, as well as melanomas, however, may spread to other regions of the body, causing symptoms in these regions. In some cases, a skin cancer is first detected based on symptoms due to metastases.﻿﻿

Melanoma can spread to nearly any region of the body, but the most common sites of melanoma metastases, as well as squamous cell carcinoma metastases, are lymph nodes, bones, the lungs, the liver, and the brain.

Spread of these cancers to bones can cause weakening that leads to fractures (pathologic fractures). Symptoms of pain in the back that shoots down the legs, weakness or numbness in the legs, or loss of control with urination or bowel movements can be warning signs of spinal cord compression due to metastases to the spine. Breakdown of bone can also lead to an elevated calcium level in the blood (hypercalcemia) that can cause nausea, vomiting, weakness, and confusion.

Cancers that spread to the lungs can cause a persistent cough or shortness of breath. Spread to the liver (liver metastases) can result in jaundice, a yellowing of the skin. Brain metastases may result in headaches, seizures, vision changes, or weakness on one side of the body.

Anxiety and Depression

Appearance can play an important role in self-image, and cancers that are located in regions visible to others can lead to anxiety and depression in some. Fortunately, plastic surgery, when needed, can do a remarkable job in restoring appearance.

When to See a Doctor

If you notice any of the signs or symptoms of skin cancer mentioned above, make an appointment to see your doctor. A dermatologist can examine your skin and determine if a biopsy is needed. This is true no matter your skin color. Not only can skin cancer be more difficult to see or look different on darker skin, but even doctors can overlook melanomas in people of color. If you are concerned, but do not feel that a concern is being addressed, be your own advocate and continue to ask questions or get a second opinion.

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It's not uncommon for people to put off seeking medical attention for a skin cancer, but the earlier these cancers are diagnosed, the better the outcomes. While finding a melanoma early can make a difference in survival, even less harmful skin cancers often require more extensive surgical techniques, and hence more disfigurement, if they are allowed to grow unchecked.