Melanoma: Diagnosis

If your healthcare provider thinks you might have melanoma, you will likely need certain exams and tests to be sure. Diagnosing melanoma starts with your healthcare provider asking you questions. They will ask you about your health history, your symptoms, risk factors, and family history of disease. Your healthcare provider will also examine you. They will take a close look at any suspicious moles or other marks on your skin. Your healthcare provider will look at your skin with the ABCDE rule in mind. This means looking at:

  • Asymmetry. One half of the mole does not match the other half.

  • Border irregularity. The edges of the mole are ragged, irregular, blurred, notched, or uneven.

  • Color. The mole has different colors in it. It may be shades of tan, brown, black, red, or other colors. Or it may have areas that appear to have lost color.

  • Diameter. The mole is bigger than 6 millimeters (about ¼ inch) across, about the size of a pencil eraser. But some melanomas can be smaller.

  • Evolving. A mole changes in size, shape, color, or appearance. The texture may feel different and it may itch, bleed, or ooze fluid.

Your healthcare provider will ask you questions about the mole, such as:

  • When you first noticed it

  • If it hurts or itches

  • If it oozes fluid or bleeds, or gets crusty

  • If it’s changed in size, color, or shape

Make sure to tell your healthcare provider if you’ve had skin cancer in the past. Also tell them if anyone in your family has had skin cancer.

Getting a biopsy

A biopsy is taking a sample of tissue that will be examined in a lab. This is needed to confirm if a suspicious mole or spot is melanoma. Your healthcare provider will likely take a biopsy of any mole or other skin mark that may look like cancer.

Types of biopsies

The types of biopsies include:

  • Excisional biopsy. This type of biopsy is often used when a wider or deeper piece of the skin is needed. The entire mole is removed, along with a small margin of healthy skin around it. First, a numbing medicine is used on the area. Using a surgical knife (scalpel), the healthcare provider removes a full thickness wedge of skin. The wound is closed with surgical thread (sutures), staples, wound closure strips, or surgical glue. This depends on the size of the incision and where it is.

  • Incisional biopsy. This procedure is similar to an excisional biopsy, but only part of the mole or mark is removed.

  • Punch biopsy. This type uses a special tool to take a small circle of full-thickness sample of skin. The tool removes a short cylinder of tissue, like an apple core. First, a numbing medicine is used on the area. The punch tool is turned on the surface of the skin until it cuts through all the layers of skin. The healthcare provider removes the biopsy sample and sometimes stitches the edges of the wound together. 

  • Shave biopsy. This type of biopsy removes the top layers of skin. They are shaved off with a sharp blade. Shave biopsies are done with a local numbing medicine. This type of biopsy is used when the risk for melanoma is low.

Lab tests of your biopsy sample

A biopsy sample is sent to a lab, where a healthcare provider called a pathologist examines them under a microscope. They may do other tests on them to see if they contain melanoma cells.

If melanoma is found, the pathologist will look at certain features of the melanoma. These include the thickness of the melanoma and the portion of cells that are actively dividing (mitotic rate). These can help find out the extent (stage) of the melanoma. The stage of melanoma helps determine treatment choices.

The pathologist might also do other tests to look for certain gene changes within the melanoma cells that could affect treatment choices.

Getting your biopsy results

Your biopsy results will likely be ready in a few days to a week or so. Your healthcare provider will tell you the results. If you do not hear from your healthcare provider, call their office. They will talk with you about other tests that may be needed if melanoma is found. Make sure you understand the results and what follow-up care you need.

Online Medical Reviewer: Jessica Gotwals RN BSN MPH
Online Medical Reviewer: Michael Lehrer MD
Online Medical Reviewer: Susan K. Dempsey-Walls RN
Date Last Reviewed: 9/1/2023
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