Abstract:

The use of immunohistochemical (IHC) stains in dermatopathology is common and increasing, however little is known regarding their specific use in the diagnosis of dysplastic nevi (DN). To quantify the use of IHC regarding the diagnosis of DN amongst dermatopathologists, histology reports for biopsy-proven DN excised between January 1, 2017 and June 30, 2020 at 6 dermatopathology laboratories in the United States, were identified. Parameters abstracted from these reports included the laboratory and dermatopathologist rendering the DN diagnosis, whether IHC was performed on the specimen, the degree of dysplasia and the type and number of stains utilized to render a diagnosis. The association of specific characteristics with IHC utilization was evaluated using chi-square test for categorical variables. 377 DN were identified from laboratories that consistently utilized IHC staining for dysplastic nevi. These diagnoses originated from four laboratories and thirty-three dermatopathologists. IHC staining was employed in 116/377 (30.8%) of the DN diagnoses. IHC staining was more commonly utilized on severely DN (63.0%, 31/49) than moderate (31%, 34/110) or mild DN (20%, 39/193). SOX-10 and Melan A (Mart-1) were the IHC stains most often employed. Multiple IHC stains were utilized on 4.2% (16/377) of the DN. Our findings suggest that there is marked heterogeneity amongst dermatopathologists’ IHC utilization in the diagnosis of DN. While a subset of dermatopathologists rarely if ever use IHC to diagnose DN, our data suggests that others employ it more commonly. Further investigation into what characteristics underlie these differences in practice and the establishment of appropriate use criteria for IHC utilization in pigmented lesions is indicated.

Financial Disclosure:
No current or relevant financial relationships exist.

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Matthew Dinehart, MD, M.Ed