Absence of Differential Cyclin D1 Immunohistochemical Protein Expression in Nevi and Melanoma Evaluated by Digital Image Analysis

Background: Distinction of superficial spreading melanoma (SSM) from compound nevi (CN) sometimes poses difficult diagnostic challenges. Herein, we studied cyclin D1 protein expression by immunohistochemistry in SSM and CN and evaluated the results by digital image analysis. Design: A total of 13 CN and 12 SSM cases were retrospectively reviewed and cyclin D1 immunohistochemistry was performed. Immunohistochemical stained slides were evaluated by digital imaging analysis that included quantification and staining intensity of the cyclin D1 expressing dermal cells. Results: Cyclin D1 expression was observed in all CN and SSM. CN-positive staining was present in 30% to 93% of the dermal nevocytes, more positive in the upper (mean 85%), than lower half (mean 57%). SSM-positive staining was present in 44% to 96% of the dermal lesion, more positive in the upper (mean 88%) than lower half (mean 49%). When analyzed based on 3+ strong staining intensity, similar regional differences in cyclin D1 expression were observed. Conclusions: Digital image analysis of Cyclin D1 expression showed no differences between CN and SSM. Quantity and regional distribution of cyclin D1 positivity were found to be similar in both lesions. Our findings argue against the routine use of cyclin D1 immunohistochemistry as a diagnostic tool for differentiating CN from SSM.