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Pruritus, or itch, is one of the most frequent dermatologic complaints. It is an unpleasant sensation characterized by the reflexive behavior to scratch and is a symptom associated with numerous inflammatory and infectious skin diseases. However, generalized and persistent pruritus without or with minimal skin changes may be a presenting feature of a variety of systemic diseases.
- Itch-specific peripheral nerves are unmyelinated afferent C-fibers.
- Pruritus depends on the complex interplay of neuroinflammatory modulators among peripheral nerves, keratinocytes, and leukocytes as well as CNS processing.
- There are numerous mediators of pruritus, although histamine is the prototypical pharmacologic target for many patients.
- Dermatologic: arising from skin disease
- Systemic: arising from noncutaneous organ systems including metabolic causes, drugs, and multifactorial disorders
- Neurogenic: arising from disorders of the central or peripheral nervous system
- Psychogenic: arising from primary psychiatric disorders
- Mixed: coexistence of more than one etiology of pruritus
- Idiopathic: pruritus of uncertain etiology