Prospective differentiation of clinically difficult to distinguish nodular basal cell carcinomas and intradermal nevi by non‐invasive Reflectance Confocal Microscopy: a case series study

Abstract Background Clinical differentiation between a nodular basal cell carcinoma ( nBCC ) and a benign intradermal nevus can be difficult. Even with additional dermoscopic evaluation, a correct diagnosis may be difficult. Currently, histopathological examination of a biopsy is the gold standard to differentiate between these lesions. However, this is an invasive technique and sampling errors can occur. In vivo Reflectance Confocal Microscopy ( RCM ) is a non‐invasive technique to evaluate a skin lesion at a microscopic level. RCM features of nBCCs and intradermal nevi have been described in research setting. However, the use of RCM for prospective differentiation between difficult to diagnose nodules into nBCC s and intradermal nevi in clinical practice has not been demonstrated yet. Objective In this study, we aim to address a common clinical scenario; to differentiate clinically and dermoscopically difficult to distinguish nodules, into nBCCs and intradermal nevi by RCM . Material and methods Six patients with clinically and dermoscopically difficult to distinguish nodular skin lesions were evaluated by RCM to differentiate prospectively between nBCC s and intradermal nevi. In five out of six cases, a 3 mm punch biopsy was obtained to confirm the RCM diagnosis. Results Observed RCM features that allowed differentiation between nBCC s and intradermal nevi were the dermal–epidermal junction patterns, the appearance of the nests and the degree of vascularization. Conclusions This case series study demonstrates the value of non‐invasive in vivo   RCM imaging in routine patient care, with respect to the prospective diagnosis of clinically difficult to distinguish nBCCs and intradermal nevi. Subsequently, biopsies of benign lesions in cosmetic areas could be avoided.