Diagnosing Melanoma
After identifying a suspect lesion, your doctor may suggest either removing it outright or further testing. Further testing is sometimes suggested because even after careful examination, it is not always clear if a suspicious mole or lesion is cancerous.
The ‘gold standard’ for determining if a suspicious mole is cancerous is a biopsy with thorough pathological examination. However, biopsies are not always needed or ideal and may not be appropriate due to the associated scarring, costs, or the presence of preexisting conditions that make healing more difficult. This is especially true for sensitive areas, such as the face or ears.
Biopsies can also cause undue stress and anxiety for patients and their loved ones. In addition, despite being the gold standard for diagnosing melanoma, it is not a perfect tool.
Due to these concerns, many doctors are turning to non-invasive techniques that can give them more information instead of – or before – a traditional biopsy.
Non-Invasive Testing
One example of a non-invasive test that can help doctors and patients decide whether to biopsy a suspicious skin lesion is the DermTech Melanoma Test (DMT). Your doctor collects a skin sample by applying a series of adhesive patches to the lesion. The adhesive patches are then mailed to a laboratory to test for markers that have been associated with melanoma. The lab looks for RNA expression of two genes, PRAME and LINC00518, and DNA mutations in a gene called TERT. Results are typically returned to your doctor within 5 business days. The doctor’s office will then follow up with you about the results.
The DermTech Melanoma Test has a negative predictive value exceeding 99%, which means that over 99% of lesions that contain no melanoma-associated markers using the test are truly negative for melanoma. This high negative predictive value has been demonstrated in a 2017 article in the Journal of the American Academy of Dermatology (JAAD)1 and a 2020 study in SKIN The Journal of Cutaenous Medicine (JAAD).2
Changes in PRAME, LINC, and TERT can be detectable before physical changes to the skin lesion are visible. If one or more of these markers are found, you and your doctor can jointly decide if it is best to move forward with a biopsy. If none of the genes are found, watchful monitoring over time may be the most appropriate course of action. However, if the DermTech Melanoma Test suggests an increased risk of melanoma, or if your doctor does not use non-invasive testing but sees a lesion as suspicious, they may biopsy your mole/lesion.
Since a biopsy is the gold standard for making a melanoma diagnosis, your doctor may suggest a biopsy regardless of your non-invasive testing result.
Traditional Biopsy
A skin biopsy is a minor medical procedure performed on a suspicious spot to retrieve a sample of cells, which will then be carefully examined under a microscope by an expert called a pathologist. A pathologist is a doctor who specializes in testing and examining cells and tissues. A dermatopathologist is a pathologist that specializes in examining skin.
The pathologist will test cells from your biopsy sample and provide you and your doctor with a comprehensive report based on their findings. This report will include a range of information found from the analysis, including whether the suspicious spot is cancer, pre-cancer, or benign (healthy).
In approximately 10-15% of biopsy samples, visual examination of the cells under a microscope alone is insufficient for a pathologist to make a definitive diagnosis. In these cases, your pathologist has several other tools to help arrive at a definitive diagnosis, including:
- Fluorescence in situ hybridization (FISH) – Fluorescence in situ hybridization (FISH) is a test that helps a pathologist map out the genetic material within cells. Using FISH, a pathologist will compare cells from your biopsy to benign tissue.
- Array Comparative Genomic Hybridization (aCGH) – Array Comparative Genomic Hybridization (aCGH) allows a pathologist to compare the number of copies of particular genes (called a copy number variation) against a known sample. While most copy number variations cause no ill effect, some are associated with increased risk of cancer.1
- Gene Expression Panels – In a Gene Expression Panel (GEP), a group of genes related to cancer are analyzed collectively to aid a pathologist in determining if cells are cancerous or benign. One example of a commercially-available test, myPath® Melanoma, measures 23 individual genes and can help a pathologist provide a definitive diagnosis in these challenging cases. The myPath® Melanoma test result is provided as a single numerical score that classifies skin lesions as likely benign, likely malignant, or indeterminate.
Waiting for Results
Waiting for results can be a stressful period for you and your family. The time required can vary significantly, based on the type of test you’ve had, the lab that is doing the testing, and the schedule of your doctor (who generally will review results before communicating them to you). Ask your doctor when you should expect your results. For many patients, this waiting period can seem like a lifetime. Though it is completely normal to worry, try to surround yourself with positivity and stay off the internet!
When your doctor asks to see you to provide you the results—don’t immediately think the worst. It is normal for patients to have to make an appointment with their doctor to receive the results. Be sure to discuss with your doctor how he/she will communicate the results to you so you know what to expect.
Were you or a loved one just diagnosed with melanoma? We have the resources to help.
