Biopsy outperforms reflectance confocal microscopy (RCM) for the diagnosis of basal cell carcinoma (BCC), according to study data published in the British Journal of Dermatology. Compared with biopsy, RCM had significantly lower specificity for BCC. Investigators advised against the implementation of RCM as a routine diagnostic tool for BCC. However, RCM may be well suited as an adjunct to dermoscopy or as a means of confirming biopsy results.
A multicenter randomized controlled trial conducted in the Netherlands compared the accuracy of RCM with punch biopsies for the diagnosis of primary BCCs and BCC subtypes. Patients with clinically suspected primary BCCs underwent RCM during typical clinical practice. This enrollment procedure was meant to reflect a “real-world setting;” patients were imaged as they arrived at the clinic and were offered punch biopsy if RCM results were negative or inconclusive. BCC subtype was characterized based on 2 metrics: aggressive vs nonaggressive and superficial vs nonsuperficial. Results from RCM and punch biopsy were compared with those from conventional surgical excision and/or clinical follow-up.
Overall, 145 patients underwent RCM and 143 underwent punch biopsy. Demographic and clinical characteristics were comparable in the 2 groups. RCM and punch biopsy both had sensitivities of 99% for BCC. However, specificity was significantly lower with RCM compared with punch biopsy (59.1% vs 100.0%; P <.001), indicating a greater number of false positives. Investigators concluded that RCM should not be routinely used as a replacement for punch biopsies.
In analyses stratified by BCC subtype, RCM had significantly lower sensitivity for detecting aggressive subtypes compared with punch biopsies (33.3% vs 77.3%; P=.003). However, the sensitivity for nonsuperficial BCC was comparable in the RCM and biopsy groups (88.9% vs 91.0%; P =.724).
Compared with previous studies of RCM, the specificity in this study was significantly lower.
Investigators cautioned against routine use of RCM to diagnose BCC in the absence of biopsy, particularly for suspected aggressive subtypes. However, RCM has utility as an add-on to dermoscopy, particularly in patients with superficial BCCs, they believed. It was suggested that RCM may also be used to confirm negative results achieved with biopsy.
Patalay R. Which method is better for the diagnosis of basal cell carcinoma: biopsy vs. reflectance confocal microscopy? [published online November 2, 2020]. Br J Dermatol. doi: 10.1111/bjd.19571