Tests for basal and squamous cell skin cancers
Most skin cancers are brought to a doctor’s attention because of signs or symptoms a person is having.
If you have an abnormal area that might be skin cancer, your doctor will examine it and might do tests to find out if it is cancer or some other skin condition. If there is a chance the skin cancer has spread to other areas of the body, other tests might be done as well.
Medical history and physical exam
Usually the first step is for your doctor to ask about your symptoms, such as when the mark first appeared on the skin, if it has changed in size or appearance, and if it has been painful, itchy, or bleeding. You might also be asked about past exposures to causes of skin cancer (including sunburns and tanning practices) and if you or anyone in your family has had skin cancer.
During the physical exam, the doctor will note the size, shape, color, and texture of the area(s) in question, and whether it is bleeding, oozing, or crusting. The rest of your body may be checked for moles and other spots that could be related to skin cancer.
The doctor may also feel the nearby lymph nodes, which are bean-sized collections of immune system cells under the skin in certain areas. Some skin cancers can spread to lymph nodes. When this happens, the lymph nodes might be felt as lumps under the skin.
If you are being seen by your primary doctor and skin cancer is suspected, you may be referred to a dermatologist (a doctor who specializes in skin diseases), who will look at the area more closely.
Along with a standard physical exam, some dermatologists use a technique called dermatoscopy (also known as dermoscopy, epiluminescence microscopy [ELM] or surface microscopy) to see spots on the skin more clearly. The doctor uses a dermatoscope, which is a special magnifying lens and light source held near the skin. Sometimes a thin layer of alcohol or oil is used with this instrument. The doctor may take a digital photo of the spot.
When used by an experienced dermatologist, this test can improve the accuracy of finding skin cancers early. It can also often help reassure you if a spot on the skin is probably benign (non-cancerous) without the need for a biopsy.
If the doctor thinks that a suspicious area might be skin cancer, the area (or part of it) will be removed and sent to a lab to be looked at under a microscope. This is called a skin biopsy. If the biopsy removes the entire tumor, it’s often enough to cure basal and squamous cell skin cancers without further treatment.
There are different types of skin biopsies. The doctor will choose one based on the suspected type of skin cancer, where it is on your body, its size, and other factors. Any biopsy will probably leave at least a small scar. Different methods can result in different scars, so if this is a concern, ask your doctor about possible scarring before the biopsy is done.
Skin biopsies are done using a local anesthetic (numbing medicine), which is injected into the area with a very small needle. You will probably feel a small prick and a little stinging as the medicine is injected, but you should not feel any pain during the biopsy.
Shave (tangential) biopsy
For a shave biopsy, the doctor shaves off the top layers of the skin with a small surgical blade. Bleeding from the biopsy site is then stopped by applying an ointment or a chemical that stops bleeding, or by using a small electrical current to cauterize the wound.
For a punch biopsy, the doctor uses a tool that looks like a tiny round cookie cutter to remove a deeper sample of skin. The doctor rotates the punch biopsy tool on the skin until it cuts through all the layers of the skin. The sample is removed and the edges of the biopsy site are often stitched together.
Incisional and excisional biopsies
To examine a tumor that may have grown into deeper layers of the skin, the doctor may use an incisional or excisional biopsy.
- An incisional biopsy removes only a portion of the tumor.
- An excisional biopsy removes the entire tumor.
For these types of biopsies, a surgical knife is used to cut through the full thickness of skin. A wedge or sliver of skin is removed for examination, and the edges of the wound are usually stitched together.
Examining the biopsy samples
All skin biopsy samples are sent to a lab, where they are looked at with a microscope by a doctor called a pathologist. Often, the samples are sent to a dermatopathologist, a doctor who has special training in looking at skin samples.
Lymph node biopsy
It’s rare for basal or squamous cell cancer to spread beyond the skin, but if it does it usually goes first to nearby lymph nodes, which are bean-sized collections of immune cells. If your doctor feels lymph nodes under the skin near the tumor that are too large or too firm, a lymph node biopsy may be done to find out if cancer has spread to them.
Fine needle aspiration biopsy
For a fine needle aspiration (FNA) biopsy, the doctor uses a syringe with a thin, hollow needle to remove very small fragments of the lymph node. The needle is smaller than the needle used for a blood test. A local anesthetic is sometimes used to numb the area first. This test rarely causes much discomfort and does not leave a scar.
FNA biopsies are not as invasive as some other types of biopsies, but they may not always provide a large enough sample to find cancer cells.
Surgical (excisional) lymph node biopsy
If an FNA does not find cancer in a lymph node but the doctor still suspects the cancer has spread there, the lymph node may be removed by surgery and examined. If the lymph node is just under the skin, this can often be done in a doctor’s office or outpatient surgical center using local anesthesia. This will leave a small scar.
Last Medical Review: 04/01/2016
Last Revised: 05/10/2016