Nail Biopsy Techniques in The Diagnosis of Nail Unit Disorders: A Narrative Literature Review

Abstract

The nail unit is far more than a cosmetic feature, as it plays vital roles in protecting the fingertip, facilitating fine motor tasks, and serving as a window to overall systemic health. While nail disorders can stem from localized issues, they often signal underlying disease processes. When typical nail conditions such as onychomycosis, longitudinal melanonychia, psoriasis, or lichen planus fail to improve with standard treatment, or when there is concern about malignancy, histological examination becomes necessary. However, nail biopsy and surgical intervention remain surprisingly uncommon in everyday dermatology practice, largely because clinicians worry about the technical demands of the procedure and its potential to cause lasting nail damage. To provide a comprehensive review of nail biopsy techniques, covering anatomical considerations, clinical indications, pre-procedural preparation, anesthetic methods, and the selection of appropriate biopsy techniques based on the site and nature of nail pathology. A narrative literature review was conducted by systematically examining, reviewing, and synthesizing published studies, textbooks, and clinical guidelines pertaining to nail unit anatomy, nail disorders requiring histopathological confirmation, and surgical biopsy techniques. The identified literature was critically appraised to extract relevant data, compare findings across sources, and synthesize the available evidence to provide a comprehensive understanding of the indications, diagnostic considerations, and surgical approaches to nail unit biopsy. Sources were identified through relevant dermatology and dermatosurgery literature published between 2016 and 2026. Nail biopsy may be performed on the nail matrix, nail bed, or nail plate using punch, excision, shave, or longitudinal techniques. Indications include chronic paronychia, nail psoriasis, longitudinal melanonychia, subungual hematoma, nail lichen planus, and both benign and malignant nail neoplasms, such as glomus tumour, squamous cell carcinoma, and subungual melanoma. Adequate anaesthesia, achieved via proximal digital block, wing block, digital collateral nerve block, or transthecal digital anaesthesia, is fundamental to procedural success. Technique selection must balance the need for an adequate specimen against the risk of permanent dystrophy, with longitudinal biopsy offering the most comprehensive evaluation of the nail apparatus. Nail biopsy is an indispensable diagnostic and therapeutic procedure in the management of nail disorders. A thorough understanding of nail unit anatomy, careful patient selection, appropriate anaesthetic technique, and judicious choice of biopsy method are essential to obtain a diagnostically adequate specimen while minimising the risk of permanent nail damage.