Evaluation of the Itchy Patient

Abstract

What is the goal of your paper? We discuss the diagnostic evaluation of patients with localized or generalized itch and provide a practical algorithm to determine appropriate anti-pruritic therapy. What questions did you seek to answer? Summarize the latest research on your topic. Several key preclinical studies in animal models have shed light on the cellular and molecular mechanisms that underlie itch sensation. Mas-related G-protein coupled receptors (Mrgprs) have been identified as key receptors expressed by peripheral sensory nerves in the skin that mediate non-histaminergic itch. Members of the Mrgpr family of receptors are responsible for signaling itch in response to various pruritic stimuli, including endogenous the neuropeptide substance P, the drug chloroquine, and many experimental pruritogens. Several cytokines derived from keratinocytes (e.g., thymic stromal lymphopoietin) or T lymphocytes (interleukin-31), previously identified for their role in promoting skin inflammation, have also been shown to be important triggers for itch. Advances in the understanding of itch pathways may one day influence diagnostic evaluation and management of patients with chronic pruritus. Clinical research efforts have focused on characterizing epidemiologic patterns associated with chronic itch, validating measurements of pruritus severity, and understanding the impact of pruritus on quality of life. A more comprehensive understanding of these issues will help physicians identify at risk populations and manage concerns around chronic pruritus more effectively. Pruritus is a common and troubling symptom associated with many dermatologic, systemic, neurologic, or psychiatric disorders. In the current manuscript, we review what is known about the pathogenesis of pruritus and discuss how an understanding of itch pathways may influence the diagnostic work up of itchy patients. We review the differential diagnosis of disorders that provoke itch and suggest key diagnostic steps that should be considered when evaluating patients with chronic pruritus.