Expert panel provides A-strength recommendation for myPath.

“For the 23-GEP test, expert consensus was reached on 8 recommendations. One recommendation received an A-strength consensus recommendation based on the existing published evidence:

  • Differentiation of a nevus from melanoma in an adult patient when the morphologic findings are ambiguous by light microscopic parameters”

Berman B, et al. Appropriate use criteria for the integration of diagnostic and prognostic gene expression profile assays into the management of cutaneous malignant melanoma: An expert panel consensus-based modified Delphi process assessment. SKIN. Sep 2019.

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Over 9% of cases are under-interpreted.

“It is estimated that at a population level, 82.8% (81.0% to 84.5%) of melanocytic skin biopsy diagnoses would have their diagnosis verified if reviewed by a consensus reference panel of experienced pathologists, with 8.0% (6.2% to 9.9%) of cases over-interpreted by the initial pathologist and 9.2% (8.8% to 9.6%) under-interpreted.”

Elmore JG, et al. Pathologists’ diagnosis of invasive melanoma and melanocytic proliferations: observer accuracy and reproducibility study. BMJ 2017;357:j2813.

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Review from multiple pathologists needed for higher likelihood of accurate histopathology.

“A ‘consensus diagnosis’ among 3 experts was also advocated both before and after morphomolecular information.”

Ferrara G, et al. The impact of molecular morphology techniques on the expert diagnosis in melanocytic skin neoplasms. Int J Surg Pathol 2013; 21:483-92.

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Overdiagnosis of melanoma occurs when evaluation criteria are complex.

“[…] in order to avoid overdiagnosis of melanoma, the significance of architectural changes of small melanocytic lesions must be interpreted with caution; the small size of the lesion hampers the evaluation of some of these criteria (symmetry, confluence of junctional nests and degree of single cell proliferation).”

Ferrara G, et al. Small-diameter melanoma: toward a conceptual and practical reappraisal. J Cutan Pathol 2012; 39:721-23.

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Histopathologic diagnosis of some melanocytic tumors is extraordinarily difficult.

“Changes in diagnosis occurred in 168 of 478 cases (35%), more frequently when the original diagnostician was a general pathologist (P = .003). A similar fraction of diagnoses were changed from malignant to benign or vice versa, in both historic and contemporary cohorts. In 64 patients (13%), changes in diagnosis led to a change in therapy. Changes in stage or grading led to the most changes in therapy (78%; 50/64) versus changes from benign to malignant or vice versa (22%; 14/64).”

Hawryluk EB, et al. Histologically challenging melanocytic tumors referred to a tertiary care pigmented lesion clinic. J Am Acad Dermatol 2012; 67:727-35.

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Discordance in the histopathologic diagnosis of melanoma.

“The discordance rate of melanomas and nevi between the referring centers and UCSF [University of California, San Francisco] was 14.3%.”

Shoo BA, Sagebiel RW, Kashani-Sabet M. Discordance in the histopathologic diagnosis of melanoma at a melanoma referral center. J Am Acad Dermatol 2010; 62:751-6.

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Change in diagnosis alters clinical management and outcome.

“[…] despite the existence of well-established criteria for the diagnosis and microscopic staging of melanocytic lesions, there is still considerable disagreement among pathologists when faced with actual histologic specimens. Misdiagnosis and/or incorrect microscopic staging of melanocytic lesions can result in unnecessary psychological distress to the patient, undertreatment or overtreatment, inaccurate prognosis and improper follow-up, and family member surveillance.”

McGinnis KS, et al. Pathology review of cases presenting to a multidisciplinary pigmented lesion clinic. Archives of Dermatology 2002; 138:617-21.

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Discordance among expert pathologists in diagnosis of melanoma.

“Some cutaneous melanocytic lesions are notoriously difficult to diagnose by histopathology. […] Diagnostic difficulties were most often encountered with Spitz naevi and dysplastic naevi.”

Veenhuizen KC, et al. Quality assessment by expert opinion in melanoma pathology: experience of the pathology panel of the Dutch Melanoma Working Party. The Journal of Pathology 1997; 182:266-72.

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Criteria for diagnosis of melanomas and melanocytic nevi need to be refined.

“In 62% of the specimens, there was unanimous agreement or only one discordant designation. Thirty-eight percent had two or more discordant interpretations. No single pathologist had a disproportionate number of discordant designations. This study mimics the consultation practice of anatomic pathology and shows the variability and discordance in diagnostic language and designation of biological behavior. The results suggest the criteria for the diagnosis of melanomas and melanocytic nevi need to be refined and more consistently applied.”

Farmer ER, Gonin R, Hanna MP. Discordance in the histopathologic diagnosis of melanoma and melanocytic nevi between expert pathologists. Hum Pathol 1996; 27:528-31.

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