Linear psoriasis and Koebner phenomenon: A review.

Linear psoriasis (LP) is an unusual form of psoriasis with an unidentified prevalence and is characterized by psoriatic papules and plaques in a Blaschko linear distribution. Based on clinical features, this disorder is divided into two types: isolated LP and superimposed LP. Previous studies have suggested that LP presenting linear appearances is closely related to the Kobner phenomenon (KP) caused by external provocation, including trauma, skin incision, drugs, infections, and striae distensae. Pathogenesis of LP is mainly attributed to the concept of genetic mosaicism but not completely illustrated until now. In this review, we summarize its epidemiological characteristics, clinicopathological features, diagnosis/differential diagnosis, corresponding therapies, focus on the possible pathogenesis of LP, and explore the relationship between LP and KP.