Prurigo as a symptom of atopic and non-atopic diseases: aetiological survey in a consecutive cohort of 108 patients

Background Prurigo nodularis Hyde (PN) is a highly pruritic condition due to a vicious circle of repeated itching and scratching. There are no representative clinical studies investigating comorbidities in a large collective of PN patients. Objective This pilot study aimed to investigate the exact distribution of the coexisting diseases in a large representative consecutive cohort of PN patients. Methods A total of 108 PN patients (36.1% male; mean age of 61.5 +/- 16.7years) were enrolled in the study. Results In 87.0% of patients, diseases underlying PN could be established (18.5% skin disease, 7.4% systemic origin, 1.8% neurological diseases, 59.3% mixed origin). Due to several possible causative co-factors, the majority of patients were classified in the group of mixed origin (59.3%). In 53.1% of these patients, at least one dermatological factor was involved in the induction of PN. Interestingly, nearly half (46.3%) of all PN patients had either an atopic predisposition or atopic dermatitis as a single cause of PN (18.5%) or as one co-factor of PN of mixed origin (27.8%). Considering the different underlying diseases, there was no significant age or gender difference. Conclusion PN does not seem to represent a characteristic symptom of one disease only. Multiple pruritogenic diseases are linked to evolution and improvement of PN upon treatment. Atopic predisposition is a major factor in nearly half of PN patients. The large collective of the present study helped detect a broad range of underlying diseases and thus to provide recommendations for rational diagnostics.