Reflectance confocal microscopy in the diagnosis of solitary pink skin tumours: Review of diagnostic clues

Reflectance confocal microscopy (RCM) is a noninvasive tool that can be helpful in the diagnosis of nonpigmented skin tumours. As RCM enables visualization of architectural and cytological structures at near-histological resolution, it can improve the diagnostic accuracy of dermoscopically equivocal solitary pink neoplasms. For management decisions, it is important to identify specific morphological clues that allow bedside classification of nonpigmented skin neoplasms into benign vs. malignant and melanocytic vs. nonmelanocytic. More specifically, the presence of a nested melanocytic proliferation at the dermoepidermal junction or dermis level permits the clinician to ascribe a given lesion as melanocytic; the identification of basaloid bright tumour islands is a key RCM feature for the diagnosis of basal cell carcinoma; and the presence of disarrayed epidermis along with small demarcated papillae is suggestive for the diagnosis of squamous cell carcinoma. The present review offers a comprehensive description of the main RCM diagnostic clues for solitary pink neoplasms that direct clinicians to the correct diagnosis and that may serve as groundwork for future prospective studies. What's already known about this topic? Solitary pink tumours represent a diagnostic challenge for clinicians as they often reveal subtle clinical and dermoscopic features. Reflectance confocal microscopy (RCM) has been shown to improve the accuracy of diagnosis of amelanotic melanoma and basal cell carcinoma. What does this study add? This review describes the criteria for RCM diagnosis of neoplasms that present as solitary pink lesions. This descriptive information may facilitate the formulation of prospective studies testing RCM-based diagnosis of amelanotic neoplasms.