Update on definition and workup of chronic prurigo

Chronic prurigo is defined as a distinct skin condition characterized by a chronic pruritus, for at least 6 weeks, with localized or generalized multiple skin lesions like papules, nodules and/or plaques, associated with signs of repeated scratching. Data from literature list several forms of chronic prurigo, the most common being prurigo nodularis. The diagnosis in chronic prurigo is made only based on clinical criteria. The pathophysiological mechanisms are still in debate, but according to the current hypotheses, it seems that these skin manifestations are the consequence of a neuronal sensitization. Different causes can trigger pruritus, which results in scratching. In time, this repetitive process leads to neuronal sensitization and to the development of papules, nodules, plaques and/or umbilicated lesions. For chronic prurigo workup there are recommended investigations to identify the different causes of pruritus and to rule out other diseases with a poor prognosis, which are taken into account for differential diagnosis.