New definitions and subtypes of chronic prurigo.

During the past few years, chronic prurigo, including prurigo nodularis, has become a focal point of considerable research attention, resulting in enhanced insights into this condition. For over two centuries, the term "prurigo" has been used in dermatology, often applied loosely to describe a range of pruritic, papulous conditions lacking clear diagnostic criteria. In 2017, the term "chronic prurigo" was introduced, delineating chronic prurigo, including prurigo nodularis, as a distinct disease entity characterized by chronic pruritus, a characteristic clinical history, and physical signs such as excoriations and the presence of pruriginous lesions. Pruriginous lesions exhibit diverse morphologies, encompassing papules (diameter < 1 cm), nodules (diameter > 1 cm), plaques, and umbilicated or linear lesions. The co-occurrence of multiple lesion types in an individual is frequently observed. The subtype and severity of chronic prurigo can be categorized on the basis of the type or number of pruriginous lesions.