2020 guidelines for the diagnosis and treatment of prurigo.

Prurigo is a treatment-resistant skin disease characterized by multiple isolated papules/nodules that cause severe itch. Prurigo papules/nodules occur either as primary lesions or as secondary lesions due to persistent scratching. The fundamental concepts and classifications of prurigo have not been sufficiently established, and considerable confusion remains regarding this topic. Clinical guidelines for chronic prurigo in Japan were published in 2012 in an attempt to reduce confusion regarding the concepts of prurigo and to standardize laboratory tests and treatments. However, the diagnostic terms for prurigo and associated concepts have changed over time, and new forms of treatment are under development. We have, thus, updated and revised the guidelines to classify prurigo based on clinical forms and causes, and disease name classifications based on the clinical form have been further simplified, such as prurigo nodularis, prurigo chronica multiformis, and prurigo (not otherwise specified). Expressions for acute, subacute, and chronic forms are not used. These guidelines outline the current concepts and specify treatments for prurigo.