Diagnostic Accuracy of Ex Vivo Confocal Microscopy for Surgical Margin Assessment of High-Risk Nodular Basal Cell Carcinoma

Background: Accurate margin assessment during surgical treatment is essential to prevent recurrences of BCC. Mohs surgery or alternative peripheral and deep en-face margin assessment (PDEMA) based on conventional histopathology are considered the gold standard for excising high-risk BCC, as it allows stepwise and complete examination of peripheral and deep margins. However, it is labor-intensive and time-consuming. EVCM has emerged as a promising alternative, allowing rapid intraoperative evaluation of fresh excised tissue. Objective: To assess the diagnostic accuracy of EVCM in a PDEMA workflow of high-risk nodular BCCs. Methods: A retrospective monocentric study was conducted at the Lausanne University Hospital (CHUV) between March 2024 and May 2025. A total of 51 patients with histologically confirmed nodular BCCs considered as high-risk and thus addressed for EVCM-assisted excision were included, yielding 171 surgical margin samples. EVCM and conventional histology-based PDEMA analyses were compared. Results: EVCM achieved an overall sensitivity of 93.8% (95% CI: 71.7-98.9%) and specificity of 98.7% (95% CI: 95.2-99.7%) compared to conventional histology. The positive and negative predictive values were 88.2% (95% CI: 63.6-97.4%) and 99.4% (95% CI: 96.4-99.9%), respectively. Conclusion: EVCM demonstrates high diagnostic accuracy for the intraoperative PDEMA of high-risk, nodular BCC. Its integration in PDEMA surgical workflows may improve efficiency, although confirmatory studies are needed in broader clinical settings.