melanoma

HOW IS MELANOMA DIAGNOSED?

HOW IS MELANOMA DIAGNOSED?


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  • - JANELLE CYR
  • - M.D.C.M | PGY-3 DERMATOLOGY
  • - UNIVERSITY OF TORONTO
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CLINICAL SUSPICION

The diagnosis of melanoma can be made clinically on examination in 80-90% of cases and is then confirmed on skin biopsy. If a dermatologist, physician, or nurse practitioner is suspicious of a particular spot during a skin exam, they may use a tool called a dermatoscope to examine the lesion more closely. A dermatoscope is a magnifying glass for the skin that uses polarized light to highlight features of the skin that may not otherwise be visible to the naked eye.

BIOPSY

If there is a suspicion of melanoma on the skin exam, it is essential that a biopsy is done. A skin biopsy takes a small piece of skin to be looked at under the microscope by a pathologist, who can see the cellular features of the skin that are not visible on a skin exam.
Biopsies are office procedures that can either be done with either a punch (cookie- cutter scalper type) or shave technique. Punch biopsies are performed using a circular or tube-shaped scalpel to remove a small piece of skin. Usually punch biopsies require sutures. Sometimes a shave biopsy is performed with a scalpel if the spot is small enough to remove it all with a single incision. Shave biopsies do not require sutures. A dermatologist may also use a regular scalpel to exercise the spot using a typical ellipse excision.

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Dermablade knife that is used to “shave” or scoop up a skin lesion

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Excision of a lesion with a regular scalpel.

Staging

There are 4 stages of melanoma that can range from stage I to IV. Higher stage numbers indicate that the cancer has affected more tissue and has spread from its original location. Staging is dependent on several factors including the thickness of the tumor (Breslow thickness), if there is ulceration present on the biopsy specimen, lymph node involvement, and if there are metastases. In order to properly stage melanoma, once a biopsy is complete, further investigations may be required, such as a sentinel lymph node biopsy or imaging with a computed tomography (CT) or positron emission tomography (PET). Staging is categorized into local, regional or distant disease, which strongly correlates with survival. Certain genetic tests looking for specific mutations (such as a mutation in a BRAF gene) can be done at this time to see if patient could be a candidate for one or more therapies.