How is nonmelanoma skin cancer diagnosed?

Diagnosing skin cancer starts with checking out a bump, spot, sore, colored area, or other mark on your skin. Any area of skin that doesn’t look normal and may have disease is called a lesion. Most lesions are not cancer, but some may be cancer. You may need to see a dermatologist. This is a healthcare provider with special training in diagnosing and treating skin problems. 

If your healthcare provider thinks you might have nonmelanoma skin cancer, you will need certain exams and tests to be sure. Diagnosing skin cancer starts with your healthcare provider asking you questions. They will ask you about your health history, symptoms, risk factors, and family history of disease. Your healthcare provider will also give you a physical exam and skin exam.

Make sure to tell your healthcare provider if you’ve had skin cancer in the past. Also tell them if anyone in your family has had skin cancer.

What is a biopsy?

Some skin lesions may look suspicious for skin cancer and need to be removed. A biopsy is a small piece (sample) of tissue that’s taken to be checked in a lab. Your healthcare provider will likely take a biopsy of any lesion that may look like cancer.

Types of biopsies

The different types of biopsies include:

• Shave biopsy. This type of biopsy removes the top layers of skin of a lesion. This type of biopsy is often used for very flat skin lesions. Your healthcare provider will inject the area with numbing medicine and then shave off the lesion with a sharp blade. Sometimes part of the lesion may be left behind. You may need another procedure to remove it completely. 

• Punch biopsy.  This type uses a special tool to take a deep sample of skin. This may be done if the lesion is small, when just a part of a larger lesion needs more study. Or it may be done if your healthcare provider wants more information about the undersurface of the lesion. The tool is like a very small paper hole punch or apple corer. It removes a short cylinder of tissue. First, your healthcare provider uses a numbing medicine on the area. The punch tool is turned on the surface of the skin until it cuts through all the layers of skin. This includes the dermis, epidermis, and the most superficial parts of the skin fat (subcutis). The provider removes the biopsy sample and may then stitch together the edges of the wound. 

• Excisional biopsy. This type of biopsy is often used when your healthcare provider needs a wider or deeper piece of the skin. The entire lesion and sometimes part of the surrounding skin is removed. First, your healthcare provider uses numbing medicine on the area. Then the provider uses a surgical knife (scalpel) to remove a full thickness wedge of skin. The wound is closed with surgical thread (stitches), staples, tape, or surgical glue. What the provider uses depends on how large the incision is and where it is.

• Incisional biopsy. This procedure is like an excisional biopsy. But only part of the lesion is removed.

Lab tests of your biopsy sample

A biopsy sample is sent to a lab, where a physician called a pathologist looks at it under a microscope.

If skin cancer is found, the pathologist will look at certain features of the lesion. These include the type of skin cancer, and the thickness of the lesion. This can help your healthcare provider figure out the extent (stage) of the skin cancer. The stage of skin cancer helps decide treatment choices.

Getting your biopsy results

Your biopsy results will likely be ready in a few days to a week or so. Your healthcare provider will give you the results. They will talk with you about other tests that you may need if skin cancer is found. Make sure you understand the results and what follow-up you need.