Diagnosing Melanoma

Early detection is crucial for diagnosing and treating your melanoma before it metastasizes or spreads to distant organs in your body. Your care team, which includes a dermatologist, radiologist, and specialists, works together to take these steps to diagnose your melanoma. 

Physical Exam

A clinical assessment of your skin lesions is one way your provider (dermatologist) diagnoses your melanoma. They use the ABCDEF rule when diagnosing your melanoma, based on: a) asymmetry, b) irregular borders, c) color, d) diameter, e) elevated surfaces, and f) funny-looking lesions 1.


Biopsies 2 are procedures providers (radiologists) use to diagnose your melanoma and confirm the stage of your cancer. A biopsy also helps detect the progression of your melanoma. The procedure involves your provider removing a tissue sample from your tumor. They send your sample to a specialist (pathologist) for examination. Your provider may also perform biopsies after your surgery to determine if all of your cancer is gone.

Imaging Tests

Imaging tests 3 are non-invasive procedures providers use for screening and diagnosing your melanoma. Some of these tests also help your provider treat your melanoma. For instance, an ultrasound gives your healthcare provider visual information about the type, size, and location of your lesion 4. Other imaging tests, such as chest x-rays, MRIs, and CT scans, help your provider diagnose the stage of your melanoma.

Stages of Melanoma

Your provider uses stages when classifying and diagnosing your melanoma 5. The stages are divided by the length and thickness of your tumor and its spread 6. These stages help your provider determine how much cancer is in your body, the location of your cancer, your treatment options, and your prognosis or outcome. Earlier stages have a better chance of survival and a lesser chance of spread. On the other hand, later stages of cancer tend to have poorer outcomes.

  • 0 (In Suti): Your melanoma is only in the area where your cancer cells first formed. Your lesions are <0.75 mm thick. 
  • I (Clinically Localized): Your melanoma is only in the outermost layer of your skin. Your lesions are 0.76-1.50 mm thick. Melanoma at this stage is “curable” with surgery and radiation to eliminate remaining cancer cells. 
  • II (Clinically Localized): Your melanoma spread past the outermost layer of skin. However, it is still localized. Your lesions are 1.51-2.25 mm thick.
  • IIIA (Regionally Metastatic): Your melanoma spread to nearby lymph nodes, lymph nodes, or nearby sites, but not yet to distant organs. Your lesions are 2.26-3.0 mm thick.
  • IV (Metastatic): Your melanoma spread to different organs of your body, like your liver or brain. Your lesions are >3.0 mm thick. Providers consider this late or advanced-stage melanoma.