Biopsy Outperforms Reflectance Confocal Microscopy in Diagnosing and Subtyping Basal Cell Carcinoma: Results and Experiences from a Randomized Controlled Multicentre Trial.

BACKGROUND Reflectance confocal microscopy (RCM) is a non-invasive method for skin assessment, allowing entire lesion evaluation up to the papillary dermis. Therefore, RCM is a potentially attractive alternative to punch biopsy in basal cell carcinoma (BCC). OBJECTIVES AND DESIGN This randomized controlled trial aimed to investigate RCM as alternative to punch biopsy in a real-world clinical setting. Primary objective was to determine the diagnostic accuracy of RCM compared to punch biopsy in diagnosing and subtyping BCC. Secondary objectives were to study related patient satisfaction and preferences. METHODS Patients with a clinically suspected primary BCC were randomized between RCM and biopsy. Conventional surgical excision or follow-up were used as reference. Sensitivity and specificity for BCC diagnosis and subtyping were calculated for both methods. BCC subtype was stratified based on clinical relevance: aggressive (infiltrative/micronodular) versus non-aggressive (superficial/nodular) histopathological subtype and superficial versus non-superficial BCC. Data on patient satisfaction and preferences werecollected using a questionnaire and a contingent valuation method. RESULTS Sensitivity for BCC diagnosis was high and similar for both methods (RCM 99.0% versus biopsy 99.0%, p=1.00). Specificity for BCC diagnosis was lower with RCM (59.1% versus 100.0%, p<0.001). Sensitivity for aggressive BCC subtypeswas lower for RCM (33.3% versus 77.3%, p=0.003). Sensitivity for non-superficial BCC was not significantly different (RCM 88.9% versus biopsy 91.0%, p=0.724). Patient satisfaction and preferences were good and highly comparable for both methods. CONCLUSIONS Biopsy outperforms RCM in diagnosing and subtyping clinically suspected primary BCC. This outcome does not support routine clinical implementation of RCM, as a replacement of punch biopsies in this patient group.