Published in:
01-03-2018 | Itch (E. Lerner, Section Editor)
Evaluation of the Itchy Patient
Published in: Current Dermatology Reports | Issue 1/2018
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Purpose of Review
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?
1)
Why is it so difficult to diagnose and treat itch? Itch is a symptom and not a disease per se, similar to pain, and can result from numerous cutaneous or systemic diseases. Furthermore, the mechanisms that underlie itch signaling in humans are still being elucidated. Finally, communication between patient and provider is critical and the importance of a thorough history is often overlooked by physicians.
2)
Is there a single right way to diagnose itchy patient? No, but employing a diagnostic algorithm may be helpful.
3)
Has any new research been published focusing on improved ways to deliver accurate diagnoses’ of the itchy patient? Types of neuropathic itch are being increasingly recognized and diagnosed by physicians, with reports demonstrating various methods that may be used to evaluate these types of itch.
Recent Findings
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.
Summary
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.