Manifestaciones ungueales en enfermedades sistémicas: ¿Hechos o anécdotas?

Background: Changes in the nails are clinical signs that are readily observable but difficult to interpret. Most of these findings are not pathognomonic of any disease; their underlying pathophysiology may be shared across multiple conditions. However, in an appropriate clinical context, nail manifestations can support or suggest the diagnosis of various systemic diseases. Methodology: A narrative review was conducted, involving an extensive literature search across multiple databases (PubMed, Scopus, Web of Science), using keywords such as “systemic diseases”, “nail disorders”, “primary hypertrophic osteoarthropathy”, and “autoimmune diseases”. Articles published between 1990 and 2024 were included, with most publications from the last 10 years. Results: This review proposes a structured approach to interpreting nail changes in the context of systemic diseases. Nail alterations are classified into three major groups: matrix abnor-malities, including keratinization disorders and disruptions in the nail plate-bed relationship, manifesting as morphological changes in the Nail plate; vascular alterations, highlighting the diagnostic relevance of capillaroscopy, which has become an essential tool for evaluating microvascular involvement; and osteoli-gamentous and perionychial alterations. Conclusion: Although nail changes are not pathognomonic for any disease, their presence warrants at a minimum a thorough and systematic evaluation.