Reflectance Confocal Microscopy Features of Focal Dermal Mucinosis Differ from Those Described for Basal Cell Carcinoma: Report of Two Cases

The purpose of this study was to describe the reflectance confocal microscopy (RCM) features of focal dermal mucinosis (FDM). The entity clinically and dermatoscopically mimics other diagnostic entities, most notably nonpigmented basal cell carcinoma. We describe two cases that highlight the dermatoscopic, RCM and histopathological attributes of FDM. RCM features such as dermal foci of dense collagen bundles oriented in the same direction, foci of haphazardly oriented thin collagen fibers separated by dark structureless areas and the absence of dark silhouettes and tumor islands are clues for FDM diagnosis. The FDM cases described here present consistent and particular RCM findings that appear to correlate well with the histopathological features of FDM. Therefore, RCM is a promising technology in diagnosing skin lesions and it use can avoid invasive procedures.