Advanced optical microscopy for skin imaging: from confocal to novel techniques.

Abstract

Timely and accurate diagnosis of dermatological diseases remains a global challenge, particularly in healthcare systems with limited access to dermatopathology services. Advanced optical microscopy techniques have emerged as powerful tools for non-invasive skin imaging, offering real-time visualization of microscopic structures with near-histological resolution. Reflectance confocal microscopy (RCM) and ex vivo confocal microscopy (EVCM) have achieved significant clinical traction, demonstrating high concordance with conventional histopathology and high diagnostic accuracy for melanocytic lesions and non-melanoma skin cancers. In parallel, developments in optical coherence tomography (OCT) and its variants-including dynamic OCT and line-field confocal OCT (LC-OCT)-provide complementary morphological and vascular information with greater penetration depth. LC-OCT further combines near-cellular resolution with simultaneous vertical and horizontal imaging, narrowing the gap between non-invasive imaging and histopathology. Emerging multimodal imaging platforms integrating OCT, Raman spectroscopy, photoacoustic tomography, and ultrasound, together with artificial intelligence-assisted image analysis, continue to expand the diagnostic capabilities of optical microscopy. Although RCM, EVCM, OCT, and LC-OCT are increasingly being incorporated into routine dermatological practice, several emerging technologies remain largely confined to specialized academic centers because of their cost, technical complexity, and limited clinical validation. This narrative review summarizes current evidence on confocal microscopy and related optical imaging technologies for skin diagnostics, emphasizing diagnostic performance, clinical utility, implementation challenges, and future directions.