Confocal Microscopy and Optical Coherence Tomography of Inflammatory Skin Diseases in Hairs and Pilosebaceous Units: A Systematic Review

The systematic review investigates the use of Reflectance Confocal Microscopy (RCM) and Optical Coherence Tomography (OCT) in diagnosing and monitoring hair follicle-based skin disorders, including acne vulgaris, rosacea, alopecia areata, and others. The review included 39 studies, with 33 using RCM, 12 using OCT, and 45 combined. These non-invasive imaging technologies were found effective in visualizing, diagnosing, and monitoring treatment effects over time in hair follicles. For example, in alopecia areata, post-treatment showed an increase in hair density associated with improvement in inflammation. However, there are currently no validated protocols or diagnostic accuracy studies for these technologies, and more large-scale studies are needed. Despite their potential, RCM and OCT have limitations such as cost, need for experienced operators, and limited penetration depth and resolution.