Diagnosis of Melanoma

Some people go to their doctor because they find something out of the ordinary on their skin. Sometimes a suspicious mole is found during a routine exam. The doctor will ask about your family history and health past. A dermatoscope is used to magnify moles during a skin exam. Your doctor may think you have melanoma based on this information.

Diagnosis of Melanoma

Skin Biopsy

The only way to confirm melanoma is with a skin biopsy. Small samples are taken and looked at in a lab for cancer cells. Types of skin biopsies:

  • Shave—The mole is shaved off in layers from the top to bottom. This is more useful when many samples are needed. Shaving does not get deep enough to get under or around the affected mole.
  • Punch—A circular device is used to cut out tissue. The deeper cut can get through all the skin layers. If needed, stitches are used to close the skin.
  • Incisional—A part of the affected skin is removed. Since more skin needs to be taken, it may be cut out in a slice or wedge. Stitches are used to close the skin.
  • Excisional—The whole area of affected skin is removed, along with an area of healthy tissue around it. Since a larger piece of the skin is taken, stitches are needed to close it.

Lymph Node Biopsy

Melanoma can spread down to the next layer of skin. In these cases, a lymph node biopsy can be done. Lymph tissue is taken and looked at in a lab for cancer. Cancer in the lymph tissue means it has spread past the mole.

Types of lymph node biopsies:

  • Fine needle aspiration—A thin needle is used to take fluid or tissue.
  • Surgical excision—The entire lymph node is removed.

Staging of Melanoma

Results from those tests and new tests will help find the stage of cancer. Staging looks at the details of the tumor and how much it has spread. This, along with age, overall health, and outlook help with planning treatment.

Staging Tests

These tests include:

  • Blood tests will show changes in blood counts, find certain proteins that point to cancer, and abnormal blood cells.
  • Imaging tests—To check for tumors in other parts of the body. Some tests use a special dye so structures are easier to see. These may include:
  • Sentinel lymph node biopsy —Sentinel lymph nodes are the first nodes that a tumor will drain into. A special dye is placed near the tumor to see which node it goes into first. Once found, it is tested for cancer. It is not likely that cancer has spread if the node is cancer-free. Lymph nodes with cancer are removed and checked until they are cancer-free.
  • Tissue tests—To look for certain aspects that can help with a treatment plan such as BRAF mutations. BRAF mutations allow certain medicines to work better than others when treating later stages of melanoma.

Stages of Melanoma

Melanoma is staged from 0 to 4 based on size, if ulcers are present, and how far the cancer has spread.

  • Stage 0—Melanoma in situ —A very localized group of abnormal cells in the top layer of skin that have not spread.
  • Stage 1A to 1B —The tumor ranges from 1 to 2 millimeter (mm) or less in thickness. There may or not be an ulcer.
  • Stage 2A to 2C —The tumor ranges from 1 to 4 mm in thickness (or 4 or more mm in thickness). There may or may not be an ulcer.
  • Stage 3A to 3D —The tumor can be any thickness. There may or may not be an ulcer. Other factors include:
    • Cancer in one or more lymph nodes
    • Lymph nodes with cancer are clustered together
    • Cancer is found in a lymph vessel that runs from the tumor to nearby nodes—cancer that is found is over 2 centimeters (cm) from the main tumor
    • Smaller tumors are on or under the skin and up to 2 cm from the main tumor
  • Stage 4 —Melanoma has spread beyond the main tumor to other parts of the body. The most common sites are the lungs, liver, brain, bones, and intestines.


General information about melanoma. National Cancer Institute website. Available at: https://www.cancer.gov/types/skin/patient/melanoma-treatment-pdq. Updated May 1, 2019. Accessed May 9, 2019.
Melanoma. EBSCO DynaMed website. Available at: http://www.dynamed.com/topics/dmp~AN~T115302/Melanoma . Updated March 26, 2019. Accessed May 9, 2019.
Melanoma. Merck Manual Professional Version website. Available at: https://www.merckmanuals.com/professional/dermatologic-disorders/cancers-of-the-skin/melanoma. Updated March 2019. Accessed May 9, 2019.
Stages of melanoma. National Cancer Institute website. Available at: https://www.cancer.gov/types/skin/patient/melanoma-treatment-pdq#_96. Updated May 20, 2016. Accessed May 9, 2019.
Tests for melanoma skin cancer. American Cancer Society website. Available at: https://www.cancer.org/cancer/melanoma-skin-cancer/detection-diagnosis-staging/how-diagnosed.html. Updated May 20, 2016. Accessed May 9, 2019.
Last reviewed February 2021 by EBSCO Medical Review Board Mohei Abouzied, MD
Last Updated: 3/10/2021

EBSCO Information Services is fully accredited by URAC. URAC is an independent, nonprofit health care accrediting organization dedicated to promoting health care quality through accreditation, certification and commendation.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

To send comments or feedback to our Editorial Team regarding the content please email us at healthlibrarysupport@ebsco.com. Our Health Library Support team will respond to your email request within 2 business days.