Description of the most severe signs in nail lichen planus: a strategy to contribute to the diagnosis of the severe stage

Background: Severe nail lichen planus (NLP) does not respond well to treatment and is often poorly considered and described in detail. Objective: We sought to describe the characteristics of severe NLP. Methods: A retrospective data analysis was performed, including the photographic records of the most compromised nails of patients with NLP over 18 years old, who consulted between 2009 and 2019 at the Instituto de Dermatologia Professor Rubem David Azulay in Rio de Janeiro, Brazil. Descriptive and statistical analysis using Fisher's exact test was performed to verify the hypothesis of independence between characteristics (P < 0.05). Results: A total of 102 patients were included. Anonychia was associated with severe thinning of the nail plate, retraction of the nail bed or nail plate, residual nail plate, loss of proximal nail fold limits, and onychoatrophy. Dorsal pterygium was associated with loss of proximal nail fold limits, onychoatrophy, and distal splitting greater than 50%. Conclusion: We provide descriptions of the most severe signs in order to facilitate the clinical diagnosis when a biopsy is not feasible and suggest an update of current NLP classifications.