Skin lesion ruled out cancer w/ Dermtech. 5 months later, invasive stage 2 melanoma.

This case is really questioning two different components of the care. The first question is “can dermtech be used as a monitoring tool in lieu of a biopsy.” The answer to this question is that it can be reasonable at times to utilize this technology as a tool if a biopsy is in a sensitive area of the body (ie: face) and the patient is concerned about the risk of a scar from a biopsy procedure, or a patient is refusing to biopsy or if a clinician has only a low suspicion of a concern. The second question is “On initial presentation, What should the clinical suspicion have been of the presenting lesion?” From the photos provided it would appear that the initial presentation was concerning in nature. It is not in a cosmetically sensitive place, and I believe most dermatologist would have biopsied the lesion at the first visit.

The question to ask here is how much might a melanoma have progressed between the initial visit in June and the follow up approximately five months later. My suspicion is that the results would have been similar if the biopsy was done initially and the five month delay likely did not result in any additional morbidity. However the growth rate is highly variable and there are articles in the literature that suggest a delay of six months could have had the effect of upstaging the cancer. It is difficult to answer this specifically because the clinical writeup does not include details of what the biopsy or excision revealed. I would need to know more to answer this more completely.

It would be better to see the mole at the time they did the stripping, but the patient does not have other moles in the area (low mole burden) and cosmetically this is not a sensitive area. Your overwhelming emphasis will be on doing a biopsy here which is standard of care.

Again, I don't know how it looked at the time of the biopsy but this is a rapidly growing lesion that is thick. If it was thinner initially it would be a better prognosis and less requirement for evaluation.

## Clinical Reasonableness of DermTech Use The use of DermTech as a screening tool in June 2024 can be considered reasonable within the context of evolving molecular diagnostic technologies and established clinical guidelines for its appropriate use. Multiple peer-reviewed publications support DermTech's clinical validation with reported sensitivity of 91% and specificity of 69% for melanoma detection, and a negative predictive value of 99%. The manufacturer's guidelines specifically indicate the test is appropriate for pigmented lesions meeting one or more ABCDE criteria where clinicians desire additional information prior to surgical biopsy, particularly in cosmetically sensitive areas, patients with surgical risk factors, or lesions being monitored for change. Standard of Care and Molecular Diagnostics Integration The standard of care for melanoma detection continues to evolve with advancing molecular diagnostic technologies. While histopathologic examination remains the definitive diagnostic method, professional organizations acknowledge that molecular testing can serve as valuable adjunctive tools in clinical decision-making. Multiple studies demonstrate that molecular diagnostics can improve diagnostic accuracy beyond visual assessment alone, with one study showing DermTech improved biopsy sensitivity from 95.0% to 98.6%. The technology addresses real clinical challenges, as even expert dermatologists demonstrate significant inter-observer variability in melanoma diagnosis. Clinical Correlation and Lesion Assessment Based on the clinical presentation described, where suspicious lesions warranted molecular testing, the correlation between DermTech results and lesion appearance must be considered within the test's documented performance characteristics and appropriate clinical context. The false negative result in this case, while unfortunate, occurs within the expected 1% false negative rate given the test's 99% negative predictive value. The practice's subsequent discontinuation of DermTech likely reflects appropriate quality improvement processes and evolving clinical experience rather than necessarily indicating unreasonable initial use. Current evidence suggests molecular diagnostics are most appropriately used as complementary tools to enhance clinical decision-making rather than replace established diagnostic methods, particularly when clinical suspicion exists based on morphologic features or patient risk factors.

It is not below the standard of care to use the Dermtech test. Although it would have been better to do a biopsy, Dermtech use was not below the standard of care. Unfortunately, it does not have 100% accuracy and a biopsy would have been preferable in this matter.

The photographs provided depict a "classic nodular melanoma", so characteristic that they could serve as examination material for dermatology board certification, with the overwhelming consensus response being “melanoma.” All hallmark features of melanoma are present and should have been immediately evident to any trained dermatologist or dermatology PA: Asymmetry – clearly visible. Border irregularity – including marked pigment diffusion resembling ink spreading through tissue paper, particularly at the inferior edge, which is a worrisome sign for melanoma. Color variation– with distinct red and black tones. Diameter– greater than 6 mm. In clinical practice, such a lesion must be considered a "malignant melanoma until proven otherwise". The standard of care dictates that an incisional or excisional biopsy is the only appropriate diagnostic step. Any alternative, including non-invasive testing, constitutes a breach of accepted practice. The use of the DermTech in this context was unnecessary and below the standard of care. This test is marketed as an adjunctive tool for "indeterminate pigmented lesions" - not for clinically obvious melanomas. Moreover, recent studies demonstrate that the sensitivity and specificity of DermTech are lower in practice than initially reported, further underscoring its inappropriate use here. In this case: 1. The patient presented with an unmistakably suspicious lesion that required immediate biopsy for diagnosis and staging. The failure to biopsy in June 2024 represents a substantial breach of the standard of care, directly contributing to delayed diagnosis and possible nodal spread. 2. The decision to substitute a DermTech test for biopsy reflects a serious deficiency in clinical judgment and constitutes a second breach of the standard of care.

The degree of damage will depend on the likely changes that can be attributed to the 5-month delay in diagnosis. 1) The most likely damage would result from the melanoma increasing in thickness. The surgical margin required and, therefore, the size of the wound and repair, increase with melanoma thickness. A five-month delay would more likely than not have resulted in increased tumor thickness, a larger wound, scar, and increased morbidity and scarring. 2) If the patient had lymph node metastases, which is unclear from the history provided, the 5-month delay could have allowed this tumor spread. Having lymph node metastases would, more likely than not, required adjunctive chemotherapy or immunotherapy, with a significant increase in morbidity and a possible decrease in mortality.

The lesion required a biopsy at initial presentation. Dermtech is not appropriate for a r/o Melanoma. It is a 'decision support tool' not an appropriate diagnostic modality when the pre-test probability that this lesion was malignant was so high.

Delay in diagnosis can cause stage progression of Melanoma resulting in lymph node biopsy and possible dissection as we have here in this case.

I believe there may have been a medical error based on the photo provided. The lesion demonstrates morphological features suspicious for malignancy, such as melanoma. For lesions with this appearance, the standard of care is to offer a biopsy. If the patient declines a skin biopsy, short-term monitoring at 3-month intervals would be prudent to ensure the lesion remains stable, regardless of DermTech results.

In this case, the failure to biopsy or closely monitor the lesion resulted in a delayed diagnosis of approximately five months. This delay may have resulted in progression to an invasive melanoma. Thin melanomas typically have a significantly better prognosis and higher 5-year survival rates compared to invasive melanomas.