Extensive Prurigo Nodularis: Characterization and Etiology

BACKGROUND/AIMS: Prurigo nodularis (PN) has multiple reported disease associations, and this study analyzes the demographics, clinical distribution and underlying etiologies in an Asian cohort. METHODS: A 1-year retrospective study was carried out on PN patients with extensive lesions (≥10) who attended a specialized itch clinic. RESULTS: 37 patients (46% male, median age 53 years) were included. In all patients, an underlying etiologic factor associated with pruritus could be identified. 49% (n = 18) of patients had a single attributable etiology, whilst 51% (n = 19) had multiple etiologies. Among all patients, dermatological disease was the most common cause (82%), of which endogenous eczema comprised the majority of cases (54%), followed by systemic disease (38%). CONCLUSIONS: All patients with extensive PN had identifiable factors associated with pruritus in this study, and a dermatological condition was the predominant etiology in both patients with mono- and multifactorial disease. A significant number of patients had underlying systemic causes.