Prurigo nodularis: a benign dermatosis derived from a persistent pruritus.

Prurigo nodularis (PN) is a benign neurodermatitis of unknown etiology characterized by firm, hyperkeratotic pruritic nodules most commonly localized symmetrically on the bilateral extensor lower extremities. PN represents a primary dermatological condition or a dermatological manifestation of repeated traumatic manipulation secondary to chronic pruritus. One must consider underlying causes of pruritus, which may include psychiatric disorders and internal disease. Given its chronicity and relapsing nature, treatment of PN can be challenging. Interruption of the itch-scratch cycle is difficult; long term prognosis remains guarded.