Melanoma Diagnosis and Staging
Getting an accurate diagnosis confirms whether melanoma is present, and determining its stage confirms how far it has spread. Together, this information helps guide your care team in building a personalized treatment plan tailored to your specific needs and type of melanoma. At Columbia’s Melanoma Center, our experts use advanced tools and biopsy techniques to ensure you receive an accurate diagnosis from the start.
How is melanoma diagnosed?
Diagnosing melanoma typically starts when you or your doctor notices an unusual mole or skin change. Your doctor will review your medical history and perform a physical exam to evaluate any suspicious spots. If melanoma is suspected, one or more of the following tests may be used to confirm the diagnosis and gather more information.
Noninvasive physical examination
A doctor will carefully examine your skin for any lesions that may be cancerous. They may also check for swollen lymph nodes, which can be a sign that cancer has spread. Tools like a dermatoscope—a handheld magnifying device—help doctors see features beneath the surface of the skin and improve diagnostic accuracy.
Digital mole mapping may also be used. This noninvasive technique creates a full-body photographic record of moles and lesions, allowing doctors to track changes over time.
Skin biopsy
If a suspicious lesion is found, your doctor will take a biopsy, or skin sample, to examine under a microscope. This helps confirm whether the cells are cancerous. The type of biopsy used depends on the size, shape, and location of the lesion:
- Shave biopsy: A thin blade removes the top layers of skin. This is often used when the risk of melanoma is low.
- Punch biopsy: A small circular blade (resembling a cookie cutter) removes a deeper skin sample, including the top, middle, and lower layers. The edges of the biopsy site are then stitched together.
- Incisional biopsy: A portion of the lesion is removed for testing.
- Excisional biopsy: The entire lesion is removed, which is preferred when melanoma is strongly suspected.
- Lymph node biopsy: If melanoma has already been diagnosed, nearby lymph nodes may be biopsied to see if the cancer has spread. This is often performed at the time of surgical removal of the melanoma.
Other diagnostic and staging tests
Once melanoma is confirmed, additional tests may be needed to check if it has spread to other parts of the body and to help determine the stage of the disease.
Imaging tests
These tests help identify whether melanoma has reached the lymph nodes, lungs, liver, brain, or other organs. Imaging often includes chest x-rays, CT scans,MRIs, or PET scans to show if and where melanoma has spread.
Blood tests
A blood test may be done to check levels of lactate dehydrogenase (LDH), especially in advanced cases. LDH levels can help determine how far the melanoma has spread and guide treatment.
Lab tests and genetic testing
A dermatopathologist may use additional lab techniques to help confirm more difficult diagnoses. These may include:
- Immunohistochemistry (IHC) – checks for cancer markers
- FISH (fluorescence in situ hybridization) – helps distinguish benign moles from melanoma
- Comparative genomic hybridization (CGH) – looks for genetic changes that suggest melanoma
Genomic Testing for Advanced Melanoma
If an advanced melanoma is found, tumor biopsy samples may be tested for mutations in genes such as BRAF, NRAS, KIT, GNAQ, GNA11, and TRK, among others. Approximately half of cutaneous melanomas have BRAF mutations, and several targeted therapies have been developed to treat patients with BRAF mutant melanoma. Other genetic findings such as KIT mutations and TRK fusions help determine if you’re a candidate for targeted therapies designed for those mutations.
Staging
Once melanoma is diagnosed, staging helps determine how much cancer is present and whether it has spread. This information is crucial for selecting the best treatment approach.
Melanomas are classified into five main stages:
- Stage 0 (Melanoma in situ): The cancer is only in the top layer of skin and has not spread.
- Stage I: The melanoma is thin and may have broken through the top layer of skin but hasn’t spread to the lymph nodes.
- Stage II: The melanoma is thicker and may have ulceration but still hasn’t reached the lymph nodes.
- Stage III: The melanoma has spread to nearby lymph nodes or nearby skin or lymph vessels.
- Stage IV: The melanoma has spread to distant parts of the body, such as the lungs, liver, brain, or other organs.
Staging also considers other features, including the depth of the tumor (called Breslow thickness) and whether it is ulcerated.