Influence of variability in assessment of Breslow thickness,mitotic rate and ulceration among US pathologists interpreting invasive melanoma,for the purpose of AJCC staging |
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| Authors: | Laura Taylor Kyle Hood Lisa Reisch Joann Elmore Michael Piepkorn Raymond Barnhill Stevan Knezevich Andrea Radick David Elder |
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| Affiliation: | 1. Department of Dermatology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania;2. Bureau of Economic Analysis, Suitland, Maryland;3. Department of Medicine, University of Washington School of Medicine, Seattle, Washington;4. David Geffen School of Medicine at UCLA, Los Angeles, California;5. Division of Dermatology, Department of Medicine, University of Washington School of Medicine, Seattle, Washington;6. Dermatopathology Northwest, Bellevue, Washington;7. Department of Pathology, Institut Curie Paris Sciences and Lettres Research University, and Faculty of Medicine University of Paris Descartes, Paris, France;8. Pathology Associates, Clovis, California;9. Department of Pathology and Laboratory Medicine, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania |
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| Abstract: | Background Melanoma staging has depended on depth of invasion (Breslow thickness, BT), mitotic rate (MR) and ulceration. In anticipation of the AJCC's eighth edition, variability in pathologists' assessment of these factors and consequently in tumor staging was assessed. Methods One‐hundred and fifteen cases of invasive melanoma, established by a consensus panel, were assessed by 187 pathologists. Variation was studied in BT, the detection of mitotic figures, and ulceration. The sources of this variation and its effect on tumor staging are considered. Results On average, participant assessments closely approached consensus BT. Greater variation was identified in the classification of mitogenicity, which (like ulceration) upstages a T1 melanoma from T1a to T1b in the seventh but not eighth edition. In cases with a T1a diagnosis by the consensus panel, 15.6% of participants identified one or more mitotic figures (indicative of a false positive); and in cases diagnosed asT1b by the consensus panel, 32.0% of participants failed to find mitotic figures (false negative). Conclusion Variability in the staging of T1 melanoma among pathologists when using the AJCC seventh edition criteria is closely related to the detection of mitotic figures, with BT playing a less prominent role. Decreased variability is expected after implementation of the eighth edition. |
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| Keywords: | dermatopathology melanocytic lesions melanoma |
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