Use in clinical practice
In Dr. Kim’s clinical experience, the PLA can be considered for suspicious pigmented lesions on cosmetically sensitive areas and for suspicious lesions in areas difficult to biopsy or excise. For example, she discussed the case of a 72-year-old woman with a family history of melanoma, who presented to her clinic with a longstanding pigmented lesion on her right upper and lower eyelids that had previously been treated with laser. She had undergone multiple prior biopsies over 12 years, which caused mild to moderate atypical melanocytic proliferation. The PLA result was double negative for PRAME and LINC in her upper and lower eyelid, “which provided reassurance to the patient,” Dr. Kim said. The patient continues to be followed closely for any clinical changes.
Another patient, a 67-year-old woman, was referred to Dr. Kim from out of state for a teledermatology visit early in the COVID-19 pandemic. The patient had a lesion on her right calf that was hard, raised, and pink, did not resemble other lesions on her body, and had been present for a few weeks. “Her husband had recently passed away from brain cancer and she was very concerned about melanoma,” Dr. Kim recalled. “She lived alone, and the adult son was with her during the teledermatology call to assist. The patient asked about the PLA test, and given her difficulty going to a medical office at the time, we agreed to help her with this test.” The patient and her son arranged another teledermatology visit with Dr. Kim after receiving the kit in the mail from DermTech, and Dr. Kim coached them on how to properly administer the test. The results came back as PRAME negative and LINC positive. A biopsy with a local provider was recommended and the pathology results showed an inflamed seborrheic keratosis.
“This case exemplifies a false-positive result. We should be sure to make patients aware of this possibility,” Dr. Kim said.
Incorporating PLA into clinical practice requires certain workflow considerations, with paperwork to fill out in addition to performing the adhesive test, collection of insurance information, mailing the kit via FedEx, retrieving the results, and following up with the patient, said Dr. Kim. “For select borderline pigmented lesions, I discuss the rationale of the test with patients, the possibility of false-positive and false-negative results and the need to return for a biopsy when there is positive result. Clinical follow-up is recommended for negative results. There is also the possibility of charge to the patient if the test is not covered by their insurance.”
Skin biopsy still the gold standard
Despite the availability of the PLA as an assessment tool, Dr. Kim emphasized that skin biopsy remains the gold standard for diagnosing melanoma. “Future prospective randomized clinical trials are needed to examine the role of genetic expression profiling in staging and managing patients,” she said.
In 2019, she and her colleagues surveyed 42 pigmented lesion experts in the United States about why they ordered one of three molecular tests on the market or not and how results affected patient treatment. The proportion of clinicians who ordered the tests ranged from 21% to 29%. The top 2 reasons respondents chose for not ordering the PLA test specifically were: “Feel that further validation studies are necessary” (20%) and “do not feel it would be useful in my practice” (18%).
Results of a larger follow-up survey on usage patterns of PLA of both pigmented lesion experts and general clinicians on this topic are expected to be published shortly.
Dr. Kim reported having no disclosures related to her presentation.