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.