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p16 Range of expression in dermal predominant benign epithelioid and spindled nevi and melanoma
Author(s) -
Oaxaca Gabriel,
Billings Steven D.,
Ko Jennifer S.
Publication year - 2020
Publication title -
journal of cutaneous pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 75
eISSN - 1600-0560
pISSN - 0303-6987
DOI - 10.1111/cup.13721
Subject(s) - melanoma , medicine , nevus , pathology , immunohistochemistry , blue nevus , spitz nevus , melanocytic nevus , dermatology , cancer research
Background Screening borderline Spitz tumors with p16 immunohistochemistry (IHC) has known utility. The applicability to other melanocytic neoplasms is not well defined. Methods Cases (N = 104) of blue, cellular blue, epithelioid blue, congenital pattern, deep penetrating, desmoplastic, desmoplastic Spitz, acral, “epithelioid” nevi, nevoid melanoma, melanoma with a precursor nevus, and non‐nevoid melanoma with Breslow thickness > 0.5 mm were stained for p16. Results Lesions showed either a single uniform pattern of expression (single/homogeneous pattern: positive, checkerboard, rare, or lost) or multiple regionally distributed patterns (multiple/heterogeneous pattern). Most cases (78%, n = 81) showed single pattern expression. Within single pattern cases, total loss was restricted to melanoma (7/81/9%). Multiple patterns were more common in melanoma (12/23, 52%). Within multiple pattern (22%, n = 23) lesions, those with a total loss component (7/23; 30%) were malignant. Total p16 loss (diffuse or regional) was not seen in a subset of nevoid melanomas (1/8; 12.5%), melanomas arising in nevi (2/6; 33%), and non‐nevoid melanomas (6/9; 66%). Total p16 loss (single pattern or part of multiple patterns) captured 61% (14/23) of melanomas and no nevi. Conclusion p16 IHC may be useful in dermal‐based melanocytic lesions. Total p16 loss is seen only in melanoma. Multiple pattern expression should prompt careful evaluation.