Estimating the potential impact of interventions to reduce over‐calling and under‐calling of melanoma

Abstract

Background Pathologists sometimes disagree over the histopathologic diagnosis of melanoma. ‘Over‐calling’ and ‘under‐calling’ of melanoma may harm individuals and healthcare systems. Objectives To estimate the extent of ‘over‐calling’ and ‘under‐calling’ of melanoma for a population undergoing one excision per person and to model the impact of potential solutions. Methods In this epidemiological modelling study, we undertook simulations using published data on the prevalence and diagnostic accuracy of melanocytic histopathology in the U.S. population. We simulated results for 10 000 patients each undergoing excision of one melanocytic lesion, interpreted by one community pathologist. We repeated the simulation using a hypothetical intervention that improves diagnostic agreement between community pathologist and a specialist dermatopathologist. We then evaluated four scenarios for how melanocytic lesions judged to be neither clearly benign (post‐test probability of melanoma < 5%), nor clearly malignant (post‐test probability of melanoma > 90%) might be handled, before sending for expert dermatopathologist review to decide the final diagnosis. These were (1) no intervention before expert review, (2) formal second community pathologist review, (3) intervention to increase diagnostic agreement and (4) both the intervention and formal second community pathologist review. The main outcomes were the probability of ‘over‐calling’ and ‘under‐calling’ melanoma, and number of lesions requiring expert referral for each scenario. Results For 10 000 individuals undergoing excision of one melanocytic lesion, interpreted by a community pathologist, a hypothetical intervention to improve histopathology agreement reduced the number of benign lesions ‘over‐called’ as melanoma from 308 to 164 and the number of melanomas ‘under‐called’ from 289 to 240. If all uncertain diagnoses were sent for expert review, the number of referrals would decrease from 1500 to 737 cases if formal second community pathologist review was used, and to 701 cases if the hypothetical intervention was additionally used. Conclusions Interventions to improve histopathology agreement may reduce melanoma ‘over‐calling’ and ‘under‐calling’.

Assessing the Potential for Patient-led Surveillance After Treatment of Localized Melanoma (MEL-SELF)

“…Evidence of their high-risk status is shown by the 6% annual incidence rate observed in the control arm. Also, recognizing the potential for overcalling owing to histopathologic disagreement about borderline lesions, 45 all melanomas diagnosed in the study period were reviewed centrally by an expert dermatopathologist (R.A.S.). A final consideration is a defining feature of patient-led surveillance: that patients will recognize suggestive changes in moles and skin lesions; this could arguably be seen as detection of a "symptomatic" lesion in contrast to abnormalities detected by physicians during a total body skin examination in the clinic.…”

Revision of the Melanocytic Pathology Assessment Tool and Hierarchy for Diagnosis Classification Schema for Melanocytic Lesions

“…The latter trend by pathologists has been ascribed to so-called diagnostic drift, the implementation of diagnostic criteria that are overly sensitive for melanoma, and also to medicolegal concerns. [55][56][57] Important considerations are that mortality rates of melanoma remain flat over time and that a subset of pT1a melanomas comprises lesions with minimal risk for recurrence or metastasis (as is also the case for melanoma in situ). 41 It is envisioned that the latter subset of melanomas with very low-risk properties, as proposed in the new MPATH-Dx V2.0 class III, may eventually be reclassified…”

“…That is, is the incidence of melanoma truly increasing, is it simply an artifact that can be explained away by distinct trends in patient care, or is it a combination of both? Evidence suggests that the increased incidence of melanoma can be attributed to a combination of greatly increased screening of individuals for melanoma, increased rates of biopsy of ever smaller clinical lesions, and increased rates of overinterpretation of small and superficial atypical melanocytic nevi and related lesions as melanoma by pathologists. The latter trend by pathologists has been ascribed to so-called diagnostic drift , the implementation of diagnostic criteria that are overly sensitive for melanoma, and also to medicolegal concerns . Important considerations are that mortality rates of melanoma remain flat over time and that a subset of pT1a melanomas comprises lesions with minimal risk for recurrence or metastasis (as is also the case for melanoma in situ) .…”

Melanoma In Situ—Getting the Diagnosis and Prognosis Right

“…Nevertheless, melanoma in situ is not an obligate precursor of invasive melanoma, and it is increasingly acknowledged that some lesions diagnosed as melanoma are clinically indolent and will never progress . The latter scenario is often referred to as overdiagnosis of melanoma …”

“…2 The latter scenario is often referred to as overdiagnosis of melanoma. 3 Worldwide, melanoma in situ has garnered growing interest as an important public health issue, as its incidence has increased at a significantly faster rate than that of invasive melanoma in different populations. One study that examined long-term incidence trends from 1982 to 2018 showed a 7% to 8% average annual percentage change in the agestandardized incidence of in situ melanoma compared with a 1% to 3% average annual percentage change for invasive melanoma, which was consistent across US White individuals as well as populations in Scotland and Queensland, despite their very different underlying incidence rates.…”