Background: Chemotherapy can cause multiple dermatological alterations, including nail changes that significantly impact patients' quality of life. This study aims to characterize the nail alterations induced by chemotherapy and assess their diagnosis through dermatoscopy.

Methodology: An observational, prospective, and descriptive study that included 140 patients from the Fundación Instituto Valenciano de Oncología (FIVO). Both clinical and dermatoscopic nail alterations in the hands and feet were evaluated, associated with the different chemotherapy drugs administered. Analyzed variables included the type of nail alteration, the treatment cycle in which they appeared, and the observed dermatoscopic patterns.

Results: The prevalence of nail alterations was 45.7%, with chromonychia being the most frequent, followed by onycholysis. Lesions affected both hands and feet in 72.3% of cases. The most common chromonichias were erythronychia (36.4%) and leukonychia (9.3%). Monoclonal antibodies, tubulin binders, and platinum complexes were the drug groups most associated with these alterations. Onychomycosis was suspected in eight patients, confirmed in four cases through mycological cultures, where non-dermatophyte fungi were isolated.

Conclusion: Nail alterations induced by chemotherapy are common, affecting nearly half of patients. Dermatoscopy allowed the identification of alterations at early stages, which can facilitate the implementation of timely therapeutic strategies and improve patients' quality of life.