Abstract
Nail dystrophies (onychodystrophies) are non-infectious processes characterized by changes in the structure, surface, color, and consistency of the nail. The wide variety of onychodystrophies is determined by their etiopathogenesis and the anatomical and physiological characteristics of the nail system. Onychodystrophies can occur both as an underlying disease and as clinical manifestations of certain skin and systemic disorders. Striking clinical examples include hypertrophic osteoarthropathy (Hippocratic nails) associated with severe systemic pathology or abnormal nail changes associated with lichen planus, which begin with the appearance of longitudinal grooves and onychorrhexis and subsequently have variable outcomes and prognoses. Many types of onychodystrophies are often nonspecific and cannot serve as pathognomonic signs of a specific disease, which, in turn, negatively impacts differential diagnostic testing and timely diagnosis. Of note is that the time a patient seeks dermatological attention does not always coincide with the onset of onychodystrophies, which directly impacts the assessment of the nail lesion severity. Like any pathological condition, onychodystrophies tend to change over time, which may be due to the duration of the pathological process and/or the action of a trigger factor, its nature, and possible associated conditions. Understanding the development of pathological nail changes can be crucial for clinical assessment and diagnosis of existing changes, selection of patient management strategies, and determining the prognosis and outcome of the disease.
This overview examines the clinical presentation of certain types of onychodystrophies depending on their severity, with the transition from one type to another, and discusses possible causes and aspects of the etiopathogenesis of these changes. The authors also attempted to systematize the severity of certain types of onychodystrophies to simplify the clinical assessment of abnormal nail changes and adequately evaluate the outcome of the disease.