Patricia Switten Nielsen shares how epidermal CD271 expression outperformed Ki67 and PRAME for diagnosing challenging melanocytic lesions, in a study presented at ECP 2026.
Patricia Switten Nielsen is Assistant Professor at the Core Center for Molecular Morphology, Department of Clinical Medicine, Aarhus University Hospital, Denmark.
The following transcript has been edited for clarity.
My name is Patricia Switten Nielsen, and I'm an assistant professor at the Core Center for Molecular Morphology, Department of Clinical Medicine, Aarhus University in Denmark.
In the study presented at the European Congress of Pathology 2026, we aimed to explore the utility of the biomarker CD271 for diagnosing challenging cutaneous melanocytic lesions.
Diagnosing such lesions remains one of the more challenging tasks in pathology, even for experienced pathologists. While key immunohistochemical markers such as Ki-67 and PRAME provide useful additional information, some lesions remain difficult to classify with confidence.
In this study, we asked whether we could gain additional information by looking beyond the melanocytic cells, specifically at the cells in the outer layer of the skin – that is the keratinocytes of the epidermal layer. We focused on the keratinocytes expression of CD271, which is a receptor for nerve growth factors, because this receptor is linked to altered skin regulation and may play a role in early melanoma formation.
We examined 156 challenging melanocytic lesions that were immunohistochemically stained for CD271, Ki-67, and PRAME. CD271 was quantified manually, while the two other markers were quantified using AI-driven image analysis.
The results for CD271 were quite striking. In benign nevi, the marker was expressed in almost all basal keratinocytes, creating a very consistent staining pattern. In contrast, this pattern was lost or disrupted in melanomas. The difference was statistically significant for all pairwise comparisons of benign, intermediate, and malignant classes.
When comparing the diagnostic performance of the marker with Ki-67 and PRAME, CD271 outperformed both markers with a ROC curve of 0.93 versus 0.84 for PRAME and 0.83 for Ki-67.
Interestingly, it was not the melanocytic cells that showed the most striking difference, but rather the surrounding epidermal cells. This highlights the potential of the epidermal niche as an additional source of diagnostic information, which warrants further investigation.
Overall, the findings of the study suggest that immunohistochemical expression of CD271 in basal keratinocytes may provide valuable diagnostic information when assessing challenging melanocytic lesions, potentially supporting accurate and timely clinical management.
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