Chronic pruritus: a narrative review

Chronic pruritus encompasses a manifestation of several cutaneous, allergic, infectious, neurological, psychological, and systemic conditions, whose etiological investigation and therapeutic strategy can be challenging. This comprehensive review aims to enhance the understanding of pruritus by highlighting important elements in its pathogenesis, including keratinocytes, Merkel cells and mast cells, nerve fibers, histaminergic and nonhistaminergic pathways, and the interaction of itch signals with the central nervous system. Diagnostic evaluation of chronic pruritus may require a meticulous approach, guided by the identification of skin lesions or signs/symptoms of underlying systemic diseases. A comprehensive evaluation, including a detailed medical history, thorough physical examination, and appropriate laboratory and imaging tests, often supplemented by skin biopsy and direct immunofluorescence, is essential. Treatment strategies for chronic pruritus should be individualized based on the etiology identified. General measures, such as emollients, serve as initial interventions, followed by targeted approaches. Topical corticosteroids, calcineurin inhibitors, phototherapy, and systemic immunosuppressants address cutaneous inflammation. Antihistamines, antidepressants, and immunosuppressants may be employed based on the specific etiology. Emerging therapies, including biologic drugs and JAK inhibitors, have potential in refractory cases.