Description

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.

Pathophysiology

• Itch-specific peripheral nerves are unmyelinated afferent C-fibers.
• Pruritus is dependent on the complex interplay of neuroinflammatory modulators among peripheral nerves, keratinocytes, and leukocytes as well as central nervous system (CNS) processing.
• There are numerous mediators of pruritus, although histamine is the prototypical pharmacologic target for many patients.

Etiology

• 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