Track: Clinical Studies

Abstract:

Introduction: Diagnostic discrepancies between outside pathology reports and internal review were reviewed from 1,726 cases received since 2022, mostly for definitive surgical management. Results: 54 (3%) of the cases had diagnostic disagreement, among which 43 (2%) involved a melanocytic lesion. Thirty-three cases of disagreement were in low-risk lesions, and the change was considered to have minimal or no medical significance. Twenty-six cases involved downstaging, often to a superficial or intraepidermal atypical melanocytic proliferation of uncertain significance (SAMPUS or IAMPUS) category (20/43 cases). Two cases were downstaged to dysplastic nevus, one to dermal nevus, and one to melanoma in situ. Six cases involved upstaging of lesions to melanoma or uncertain malignant potential, and seven cases involved increasing the stage of the melanoma. Challenging cases included desmoplastic melanoma, three of which had been initially misdiagnosed as benign. Capsular nevus cell deposits were mistaken for melanoma metastases in two cases. Conclusion: There is variability and subjectivity in diagnosing some melanocytic lesions. The preferred use of an “uncertain” category in many of these cases reflects these limitations. However, the majority of cases reviewed (97%) resulted in diagnostic agreement, perhaps because the surgical selection criteria resulted in a relatively high proportion of more advanced lesions for which diagnosis was typically more reproducible.

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Olivia Leung