, results from an exploratory study showed.
The findings “could in part play a role in the rising incidence of early-stage melanoma with low risk of progression or patient morbidity, thereby contributing to increasing rates of overdiagnosis,” researchers led by co–senior authors Joann G. Elmore, MD, MPH, of the University of California, Los Angeles, and Raymond L. Barnhill, MD, MBA, of the Institut Curie, Paris, wrote in their study, published online in JAMA Dermatology.
To investigate the characteristics associated with rendering higher-grade diagnoses, including invasive melanoma, the researchers drew from two national data sets: the Melanoma Pathology (M-Path) study, conducted from July 2013 to May 2016, and the Reducing Errors in Melanocytic Interpretations (REMI) study, conducted from August 2018 to March 2021. In both studies, pathologists who interpreted melanocytic lesions in their clinical practices interpreted study cases in glass slide format. For the current study, researchers used logistic regression to examine the association of pathologist characteristics with diagnosis of a study case as higher grade (including severely dysplastic and melanoma in situ) vs. lower grade (including mild to moderately dysplastic nevi) and diagnosis of invasive melanoma vs. any less severe diagnosis.
A total of 338 pathologists were included in the analysis. Of these, 113 were general pathologists and 225 were dermatopathologists (those who were board certified and/or fellowship trained in dermatopathology).
The researchers found that, compared with general pathologists, dermatopathologists were 2.63 times more likely to render higher-grade diagnoses and 1.95 times more likely to diagnose invasive melanoma (P < .001 for both associations). Diagnoses of stage pT1a melanomas with no mitotic activity completely accounted for the difference between dermatopathologists and general pathologists in diagnosing invasive melanoma.
For the analysis limited to the 225 dermatopathologists, those with a higher practice caseload of melanocytic lesions were more likely to assign higher-grade diagnoses (odds ratio for trend, 1.27; P = .02), while those affiliated with an academic center had lower odds of diagnosing invasive melanoma (OR, 0.61; P = .049).
The researchers acknowledged limitations of their analysis, including the lack of data on patient outcomes, “so we could not make conclusions about the clinical outcome of any particular diagnosis by a study participant,” they wrote. “While our analyses revealed pathologist characteristics associated with assigning more vs. less severe diagnoses of melanocytic lesions, we could not conclude that any particular diagnosis by a study participant was overcalling or undercalling. However, the epidemiologic evidence that melanoma is overdiagnosed suggests that overcalling by some pathologists may be contributing to increasing rates of low-risk melanoma diagnoses.”
In an accompanying editorial, authors Klaus J. Busam, MD, of the department of pathology and laboratory medicine at Memorial Sloan Kettering Cancer Center, New York, Pedram Gerami, MD, of the department of dermatology at Northwestern University, Chicago, and Richard A. Scolyer, MD, of the Melanoma Institute, Wollstonecraft, Australia, wrote that the study findings “raise the question of whether subspecialization in dermatopathology may be a factor contributing to the epidemiologic phenomenon of overdiagnosis – that is, the discordance in the rise of melanoma incidence and relatively constant annual mortality rates over many decades. The findings also invite a discussion about strategies to minimize harm from overdiagnosis for both patients and the health care system.”
To minimize misdiagnoses, they continued, efforts to facilitate diagnostic accuracy should be encouraged. “Excisional (rather than partial) biopsies and provision of relevant clinical information would facilitate rendering of the correct histopathologic diagnosis,” they wrote. “When the diagnosis is uncertain, this is best acknowledged. If felt necessary, a reexcision of a lesion with an uncertain diagnosis can be recommended without upgrading the diagnosis.”
In addition, “improvements in prognosis are needed beyond American Joint Committee on Cancer staging,” they noted. “This will likely require a multimodal approach with novel methods, including artificial intelligence and biomarkers that help distinguish low-risk melanomas, for which a conservative approach may be appropriate, from those that require surgical intervention.”
The study was supported by the National Center for Advancing Translational Sciences and by the National Institutes of Health. One author disclosed receiving grants from the National Cancer Institute during the conduct of the study, and another disclosed serving as editor in chief of Primary Care topics at UpToDate; other authors had no disclosures. Dr. Busam reported receiving nonfinancial support from the American Society of Dermatopathology. Dr. Gerami reported receiving consulting fees from Castle Biosciences. Dr. Scolyer reported receiving an investigator grant from the National Health and Medical Research Council of Australia during the conduct of the study and personal fees from several pharmaceutical companies outside the submitted work.