Melanoma Diagnosis and Staging

There are many types of melanoma — the main four are superficial spreading melanoma, nodular melanoma, acral lentiginous melanoma and lentigo malignant melanoma. Rarer conditions include spitzoid melanoma, nevoid melanoma, desmoplastic melanoma, mucosal melanoma and uveal melanoma (also called ocular melanoma).

When it comes to choosing the optimal melanoma treatment, diagnosing the subtype of melanoma correctly is crucial. There are several tests to check for the disease.

Medical history and physical exam: The care team will first ask about melanoma symptoms — any changes in skin appearance or mole size, and if the skin has been painful, itchy or bleeding. They may also inquire about the patient’s risk factors for melanoma, including a personal or family history of skin cancers, tanning and sunburns. 

A skin exam is the initial diagnostic test, as most melanomas are visible to the naked eye. During the exam, the doctor will assess the area's size, shape, color and texture, noting any bleeding, oozing or crusting, and may check the patient’s body for other suspicious spots. 

When melanoma spreads, it often goes to nearby lymph nodes first, making them larger. That’s why the doctor may also feel the lymph nodes under the skin in the neck, underarm or groin near the abnormal area.

Dermoscopy: This specialized technique by a board-certified dermatologist involves a handheld tool that magnifies and brightens the skin, so the care team can look at the mole or skin very closely. During dermoscopy, the care team may take digital images of the area to monitor any changes over time.

Blood chemistry studies: The care team may check the patient’s blood for lactate dehydrogenase (LDH). High levels of this enzyme are associated with melanoma. A circulating tumor DNA test can also offer some information on disease activity, including response to surgery and therapy.

Skin biopsy: The only way to diagnose melanoma definitively is through a skin biopsy, which involves surgically removing a suspicious tissue sample and sending it to a pathologist for examination.

There are distinct types of skin biopsy:

• Shave biopsy is used to remove the abnormal growth using a razor blade.
• Punch biopsy utilizes a special round instrument to remove a circular tissue sample.
• Incisional biopsy involves removing a section of abnormal growth.
• Excisional biopsy involves removing all abnormal growth.

Melanoma typically forms in the top layers of the skin and then grows both wider and deeper. Melanoma is easier to cure when it’s caught before it spreads. Annual screening for melanoma by a board-certified dermatologist is recommended.

Genetic Testing: Generally, a family history of melanoma appears to increase the risk of melanoma by about twofold. Tell the care team about any personal history of melanoma and dysplastic nevi, or a family history of melanoma and other cancers.

A dermatopathologist can perform wide-ranging molecular testing of most melanoma subtypes, while a molecular pathologist can test for specific mutations — such as BRAF and KIT — leading to more targeted treatment options.

“The number one question that patients ask when diagnosed with melanoma is whether they’re going to survive,” says Gaurav Singh, M.D., M.P.H., F.A.C.M.S., Mohs micrographic surgeon and dermatologist at City of Hope Cancer Center Chicago. “I utilize the latest tools, including gene expression profiling and circulating tumor DNA, which allow me to not only perform the Mohs surgery with the best possible cure rates and least amount of scarring, but also provide patients with the latest information on their prognosis and survival. Advanced surgical techniques combined with prognostic and predictive tools gives our patients the best chance forward.”

Staging — a vital step in the diagnostic process — informs doctors how much cancer is in the body and whether it has spread to other areas. Cancers with similar stages tend to have a comparable outlook and are often treated in the same way.

For melanoma, staging is based on the American Joint Committee on Cancer (AJCC) TNM system, which assigns stages based on three factors:

• Tumor thickness and ulceration (T)
• Spread to nearby lymph nodes (N)
• Metastasis to other parts of the body (M)

Numbers or letters following T, N and M present further details about each factor. In general, lower numbers mean less cancer spread, higher numbers mean more advanced cancer and earlier letters, like A, mean a lower stage.

To assign an overall stage, the complete T, N and M categories information is combined in a process called stage grouping. Below are the stages the care team may discuss with the patient. Always ask the doctor to explain melanoma staging in a way that’s easy to understand.