Ancillary immunohistochemistry testing for loss of p16 in melanoma: A systematic review and meta‐analysis of diagnostic accuracy studies

BackgroundAncillary immunohistochemistry testing for p16 loss has been proposed as a diagnostic tool for melanoma, but its accuracy remains uncertain.MethodsA systematic review and meta‐analysis were conducted on 26 studies involving 979 melanomas and 974 nevi.ResultsThrough bivariate analysis of data across all cut‐off values, the sensitivity and specificity were calculated to be 0.55 (95% confidence interval [CI]: 0.38, 0.70) and 0.85 (95% CI: 0.70, 0.94), respectively. Summary estimates of diagnostic accuracy fell below recommended thresholds for effective tests, but subgroup analysis suggested that p16 loss could aid in diagnosing ambiguous lesions as melanoma in certain scenarios. However, the presence of p16 expression in these contexts does not definitively rule out melanoma. The findings were limited by underpowered exploratory study designs at risk for bias in patient selection and test interpretation.ConclusionsWhile the use of p16 immunohistochemistry for detecting melanoma is not universally reliable, it may serve as a confirmatory test in differential diagnoses involving common, congenital, acral, Spitz, and deep penetrating nevi. Nevertheless, further studies are needed to validate its utility. Until then, the application of p16 immunohistochemistry in melanoma diagnosis should be regarded as experimental.