Is it skin cancer?

Skin cancer is the most common form of cancer, with more than 3.5 million cases affecting more than two million people each year, according to the Skin Cancer Foundation. Early detection and treatment are key, which is why it's vital to pay attention to moles and other marks on your skin (and to see a dermatologist once a year for a skin exam).

There are three main kinds of skin cancer: Basal cell carcinoma, squamous cell carcinoma, and melanoma, the most lethal form (shown at left). In addition, there are "precancers" called actinic keratoses, along with iffy moles (dysplastic nevi) that could be worrisome. Keep clicking as Dr. Michele Green, a skin cancer expert in New York City, walks us through photos showing the things you should be looking for. The images are graphic, but looking at them just might save your life, or that of someone you love.

Is it skin cancer?

Here's a hand with several actinic keratoses - all those red, scaly patches. These back-of-the-hand lesions are common in older golfers and others who spend a lot of time outdoors. Without treatment, actinic keratoses can turn into a form of cancer known as squamous cell carcinoma.

Is it skin cancer?

Sometimes it's hard to tell one kind of skin cancer (or precancerous lesion) from another. But this is a classic actinic keratosis - flat, pink and scaly. Yes, you might be able to pick this crusty lesion off with your fingers. But it would grow back. The right thing to do is see a dermatologist and have it removed.

Is it skin cancer?

This raised, scaly patch is an actinic keratosis. It's been marked with ink - in preparation for its removal.

Is it skin cancer?

The red patch on the ear might not look like much, but it's actually an actinic keratosis. These lesions typically feel rough and sometimes bleed. Actinic keratoses tend to occur on areas of skin that get a lot of sun exposure, including the ears, face, scalp, as well as the backs of the hands and the neck.

Is it skin cancer?

The ears are another spot where actinic keratoses like these are apt to show up.

Is it skin cancer?

This could be an actinic keratosis or squamous cell carcinoma. In general, the prognosis is good for people with squamous cell carcinoma. But a squamous cell carcinoma that develops on the lips or another mucous membrane is more likely to spread (metastasize) - and in rare instances metastatic squamous cell carcinoma proves deadly.

Is it skin cancer?

Dr. Green says these white, crusty actinic keratoses look a bit unusual. But like all actinic keratoses, they can turn cancerous.

Is it skin cancer?

This is a classic basal cell carcinoma - the least dangerous form of skin cancer. Note the red color and the almost pearlescent look. These cancers seldom metastasize but can grow larger - and so should be removed. To minimize scarring and disfigurement, a basal cell carcinoma on the face should generally be taken off with a specialized form of surgery called Mohs. Elsewhere on the body, the lesions are often simply burned off.

Is it skin cancer?

This basal cell carcinoma has turned into a bloody, oozy mess. Be suspicious of any lesion that bleeds and doesn't heal, Dr. Green says.

Is it skin cancer?

Another basal cell carcinoma - note the pearlescent look. For lesions like this, it's generally best to use Mohs surgery to minimizes scarring and prevent disfigurement. Mohs can usually be performed on an outpatient basis.

Is it skin cancer?

Some basal cell carcinomas, like this one, have a raised border.

Is it skin cancer?

This basal cell carcinoma of the eyelid is another candidate for Mohs surgery. Skin cancers are common on the face because it gets so much sun exposure over the years.

Is it skin cancer?

Here's a basal cell carcinoma that looks like a scar. Atypical lesions like these can be tricky to diagnose. When she sees a lesion like this, Dr. Green says she typically asks the patient if it's the aftermath of some wound. If not, odds are it's got to come off.

Is it skin cancer?

Dermatologists take a close look at pigmented lesions like this one because in rare instances they turn out to be melanoma - the most dangerous kind of skin cancer. But the raised lesion shown here is actually a basal cell carcinoma.

Is it skin cancer?

This isn't skin cancer but a dysplastic nevus (mole). Lesions that resemble this dysplatic (the word means the cells look irregular under the microscope) lesion are generally benign. But if you have a lot of them, you may be more likely to develop skin cancer.

Is it skin cancer?

Another dysplastic nevus. Note the irregular border and the different shades of color. Those can be signs of melanoma - but not in this case.

Is it skin cancer?

Asymmetry is another worrisome sign - that is, when one half of the lesion doesn't look like the other. This happens to be a dysplastic nevus, but asymmetry is also a hallmark of melanoma.

Is it skin cancer?

This flat, speckled lesion is a dysplastic nevus.

Is it skin cancer?

This close-up shot shows another dysplastic nevus, though the dark color is more typical of a melatoma. "This would scare me," says Dr. Green.

Is it skin cancer?

Here is the most worrisome kind of skin cancer: Melanoma. Note the color - it's dark, almost black. The irregular, scalloped border seen in this lesion is another hallmark of melanoma. Over time, melanomas grow and thicken. The thicker the lesion, the worse the prognosis. This one should have been removed long ago.

Is it skin cancer?

This melanoma has the very dark coloration and the varied (variegated) color. In addition, it's highly asymmetrical.

Is it skin cancer?

Here's a black-and-blue nail, right? Not hardly. It's a melanoma of the nailbed, and lesions like this can be deadly.

Is it skin cancer?

This is a very large melanoma on the scalp. It takes awhile for a melanoma to grow this big. For some reason, people sometimes put off going to the doctor even when they suspect they have a problem. In other cases, melanomas are allowed to grow big because they develop on a hard-to-see part of the body.

Is it skin cancer?

Melanoma of the face is very common.

Is it skin cancer?

This melanoma is fairly advanced - as evidenced by the raised portion. As melanomas grow and thicken, they become harder to treat successfully.

Is it skin cancer?

Though much more common in fair-skinned people, skin cancer affects blacks and other racial/ethnic groups too. Here's a melanoma on dark skin.

Is it skin cancer?

The pink area next to this melanoma on dark skin may be the result of what Dr. Green calls "regression" - the body has fought back at the lesion, shrinking it a bit. But the body can't cope with a lesion like this. It needs to come off. Yesterday.

Is it skin cancer?

This blackish lesion is a melanoma. But melanomas can also look reddish, or even bluish.

Is it skin cancer?

This melanoma has been growing for years. Lesions this extensive generally cannot be successfully treated - which is why early removal is so essential.

Is it skin cancer?

Here's a bluish-black melanoma. Sometimes melanomas start out as one color and slowly change.

Is it skin cancer?

Melanomas on the foot are rare but sometimes deadly - because people may mistake them for warts, delaying treatment by a doctor.

Is it skin cancer?

A melanoma this thick is almost certain to prove lethal.

Is it skin cancer?

This nodular lesion is a squamous cell carcinoma. These lesions are seldom fatal but can be disfiguring.

Is it skin cancer?

Here's a squamous cell carcinoma of the nail.

Is it skin cancer?

Squamous cell carcinoma on the back of the hand.

Is it skin cancer?

Just a scab? No, this is a squamous cell carcinoma. Because skin cancers often extend deeper into tissue that is readily apparent, the surgery required to remove this lesion is likely to be very extensive - and potentially disfiguring. Better to have it removed before it gets so big.

Is it skin cancer?

Removal of a squmous cell carcinoma on the nose, like the one shown here, is another that could prove disfiguring.