Reflectance confocal microscopy - Real-time In vivo imaging of basal and squamous cell carcinomas

Reflectance and confocal microscopy (RCM) is an in vivo non-invasive imaging tool that captures horizontal images of the epidermis and superficial dermis at nearly the same resolution of routine histopathology. Due to the overlying superficial scaling, RCM characterization of squamous cell carcinomas (SCCs) and associated keratinizing tumors is difficult to visualize due to the obscure appearance of underlying structures. To date, although an increasing frequency of abnormal RCM features are observed across the spectrum, only a few authors have described the features of SCCs. One recent study suggested a disarranged and atypical honeycomb pattern along with round nucleated cells within the spinous/granular layers and round vessels traversing through dermal papilla as key features of SCC. Meanwhile several RCM features have been linked to basal cell carcinomas (BCCs) regardless of type including: Variable architectural disarray of the epidermis, A uniform pattern of elongated monomorphic nuclei polarized along the same axis, Abundant vessels with prominent tortuosity, Mononuclear inflammatory infiltrate admixed with carcinoid basal cells, Tightly packed cells in the papillary dermis with a nodular/cord-like growth pattern, Palisading tumor cell nuclei, Peri-tumoral dark cleft-like spaces representing mucinous edema, The presence of bright dendritic cells and melanophages in pigmented BCC Our objective is to identify and describe characteristic RCM findings of SCCs and BCCs by imaging biopsy-proven lesions and reviewing the most recent literature. We will also explain how these features may facilitate diagnosis and recognize future trends for research. Applications of RCM criteria concerning surgical management of these lesions will also be discussed.