Medical Student Research Forum Posters

Early diagnosis of melanoma is crucial to improved patient survival. Some melanomas can be difficult to diagnose from histopathology alone, and inter-observer disagreement among dermatopathologists in 15-35% of cases1 can delay diagnosis. PRAME (PReferentially expressed Antigen in MElanoma) is a tumorassociated antigen found to be overexpressed in human melanomas, making it a helpful tool in differentiating between benign vs. malignant melanocytic lesions. PRAME immunohistochemistry (IHC) has been used increasingly in dermatopathology practice, but there is currently no single biomarker or IHC stain that is diagnostic when used alone. S100A8 is a calcium-binding protein found to be highly expressed in certain inflammatory conditions and human cancers2,3. It was recently found by Kiuru et al. to be expressed by the keratinocyte microenvironment of melanomas but not that of melanocytic nevi4 , suggesting its role as a melanoma biomarker. The diagnostic utility of S100A8 IHC when compared to other commonly used melanoma biomarkers, including PRAME, has not yet been assessed. The objective of this study was to compare S100A8 immunohistochemistry with PRAME immunohistochemistry in benign and malignant melanocytic tumors to determine the diagnostic utility of S100A8.