Diagnosing Melanoma

Doctors at NYU Langone’s Perlmutter Cancer Center diagnose melanoma through an examination of the skin and a biopsy, in which a small sample of tissue is removed for examination under a microscope.

If melanoma is diagnosed, a team of dermatologists, dermatopathologists, oncologic surgeons, reconstructive plastic surgeons, medical oncologists, radiation oncologists, and pathologists combine their expertise to customize a treatment plan for you.


Skin Examination

Your doctor can look at a mole or pigmented area of the skin to determine whether it is suspicious for melanoma. The doctor may also use a dermatoscope, a handheld lens that lights and magnifies the skin. This device allows your doctor to see more deeply into the skin to identify subtle features of a mole or tumor and determine if a biopsy is needed.

A doctor may also notice a change in a mole by comparing it to a previous photograph of your skin, taken during a photography exam.

Dr. Jeffrey Weber with Team

Our team of multidisciplinary specialists work together to develop a treatment plan that works best for you.

Skin Biopsies

Suspicious growths may need to be biopsied. A skin biopsy is an in-office procedure typically performed using local anesthesia and one of several techniques. The doctor removes a sample of tissue and sends it to a laboratory at Perlmutter Cancer Center, where a dermatopathologist, a doctor who studies biopsy tissue and identifies diseases of the skin, examines it under a microscope to see if it is cancerous.

Punch Biopsy

To remove small suspicious growths, doctors may use a tool called a punch, which resembles a small cookie cutter. The doctor uses it to remove the suspicious mole or pigmented area. The skin is then stitched together.

Excisional Biopsy

For larger growths, doctors may perform an excisional biopsy, in which they use a scalpel, or surgical blade, to completely remove the growth, along with some healthy skin. This procedure can be performed with local anesthesia in the doctor’s office. The doctor closes the skin with stitches.

Shave Biopsy

Doctors may use this type of biopsy to remove a growth that forms a bump on the skin. Your doctor uses a small surgical blade to shave off a thin piece for examination. At Perlmutter Cancer Center, a shave biopsy is performed only when the suspicion of melanoma is low and the blade can go deep enough to obtain adequate tissue for evaluation.

Tissue Evaluation

After a growth is removed, a dermatopathologist evaluates its features under a microscope to determine whether it is melanoma or another type of skin cancer, such as basal or squamous cell skin cancer, or if it is benign, meaning noncancerous.

If it is melanoma, the dermatopathologist also studies the borders and thickness of the tumor and identifies other microscopic features that may help determine how the cancer should be treated. A pathology report is sent to your dermatologist, who determines what treatment is needed.

Lymph Node Biopsy

Melanomas can be aggressive and tend to spread to the lymph nodes—small glands located throughout the body that filter fluid from tissues and trap viruses, bacteria, and potential tumor cells.

Sentinel Lymph Node Biopsy

If a melanoma tumor is 1 millimeter in thickness or more, and if the nearby lymph nodes don’t feel swollen during a physical exam, our doctors may recommend a sentinel lymph node biopsy—a procedure that checks whether cancer cells are present in nearby lymph nodes.

Our doctors may also recommend a sentinel node biopsy for melanomas that are less than 1 millimeter thick if microscopic features indicate that it might be aggressive. For growths less than 1 millimeter thick that do not have aggressive features, a sentinel lymph node biopsy is usually not necessary.

Perlmutter Cancer Center surgical oncologists were among the first to demonstrate that this procedure is feasible and valuable.

Our doctors were among the first to show that sentinel lymph node biopsy can detect whether melanoma has spread to nearby lymph nodes.

During a sentinel lymph node biopsy, surgeons in an operating room inject a tracer consisting of a radioactive fluid and a blue dye around the area where the biopsy was performed. The tracer travels through skin tissue and lymph vessels—hollow structures that carry lymph fluid—to the nodes near the tumor. The first node or nodes to absorb the tracer are called the sentinel nodes.

Doctors can find this node or nodes using a gamma probe, a device that detects the radioactive fluid. This helps them determine where to make an incision. The blue dye also helps them identify the proper node or nodes during surgery.

After removal, the sentinel lymph node or nodes are sliced into many smaller sections for evaluation under a microscope by a dermatopathologist. Special stains are used to help detect even the smallest traces of melanoma present in the nodes. The results of these studies take several days.

If the sentinel node or nodes are free of cancer cells, no additional lymph nodes need to be removed because the melanoma has most likely not spread.

If the sentinel node or nodes contain cancer cells, your surgeon may recommend that additional nodes in the area be surgically removed and evaluated under a microscope to determine whether they contain melanoma cells. Knowing how many lymph nodes contain cancer cells helps doctors determine how advanced the condition is and what treatment options may work best.

You may experience some pain and swelling at the incision site for a few days after the removal of lymph nodes, and you may go home with a drain in place to help reduce swelling. Doctors can teach you how to care for the drain, and prescribe medications to help manage any discomfort.

Needle Biopsy

If lymph nodes feel swollen during a physical exam, doctors can use a needle biopsy, in which they insert a small needle into a lymph node to withdraw cells for examination under a microscope. If the node contains cancer, the doctor may recommend removing more lymph nodes in the area.

Imaging Tests

If melanoma cells are present in the lymph nodes, doctors may perform a variety of imaging tests to determine if the cancer has spread to other parts of the body, such as the lungs, brain, or liver.

CT Scans

A CT scan uses X-rays to create computerized three-dimensional, cross-sectional images of the body. A CT scan of the chest and abdomen can help your doctor determine if the melanoma has spread to the lungs or liver.

MRI Scans

Your doctor may order an MRI scan in addition to or instead of a CT scan. An MRI scan uses a magnetic field and radio waves to create computerized, three-dimensional images of structures in your body. The scan can help determine whether melanoma has spread to the brain. Before the scan, a contrast dye may be injected into a vein to enhance MRI images.


If doctors need more detailed images, they may use a combined PET/CT scan. The CT portion of the scan uses X-rays to create cross-sectional images of the body, while the PET scan reveals how active a tumor is by detecting how quickly cells are metabolizing or processing glucose, or sugar. Rapid processing is a sign of cancer. A PET/CT can also help determine whether cancer has spread.

Before the test, a small amount of radioactive glucose is injected into a vein. The substance collects in cancer cells, which are detected by a computer.

Additional Tissue Testing

If you have melanoma, your doctors may ask that the cancerous tissue be examined for genetic changes or mutations. Certain gene mutations found in melanoma can tell doctors whether targeted drugs, which are designed to specifically block the growth of cancer cells, might be effective.