Overview of onychoscopy: Dermoscopy for the nail

Background: Dermoscopy, a noninvasive imaging technique, enhances visualization of subsurface skin and nail structures by reducing surface light reflection. When applied to the nail unit—termed onychoscopy —it provides critical diagnostic information about pigmentation, vascularity, and structural alterations. However, the nail’s distinct anatomy limits the applicability of traditional skin dermoscopy algorithms, necessitating nail-specific interpretive frameworks. Objective: This comprehensive review of the literature outlines key principles of onychoscopy, emphasizing its clinical relevance, characteristic dermoscopic patterns in benign, malignant, and inflammatory nail conditions, and its educational importance for physician associates (PAs) in clinical practice. Results: Onychoscopy facilitates differentiation between melanocytic and nonmelanocytic pigmentation, enables early detection of nail melanoma through recognition of irregular line patterns, color heterogeneity, among other established melanoma patterns and supports diagnosis of nonmalignant disorders such as psoriasis, lichen planus, and onychomycosis. For PAs, proficiency in dermoscopic interpretation aligns with recent competency guidelines promoting dermoscopy education, which will help drive early diagnosis, reduced biopsy rates, and improved patient outcomes. Conclusion: Onychoscopy represents an indispensable extension of the dermatologic examination. Mastery of nail-specific dermoscopic criteria improves diagnostic accuracy, guides management, and fosters multidisciplinary collaboration. In addition, expanding dermoscopy education within PA training programs and post-PA training for both dermatology and primary care PAs is a practical step toward earlier recognition of serious nail pathology and comprehensive, evidence-based dermatologic care.