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Approaching the Pruritic Patient

»	What is the most common symptom of dermatologic disease?
»	What is an “itch”?
»	Is an itch a separate modality of pain or a submodality of pain?
»	What causes an itch?
»	Describe the difference between localized and generalized pruritus.
»	What is the best approach to evaluation of a patient with localized pruritus?
»	What are the common causes of localized pruritus?
»	What is notalgia paresthetica?
»	What is the physician’s best approach when seeing a patient with generalized pruritus?
»	After obtaining a complete history and physical examination, what clinically oriented classification scheme should be followed?
»	What are common causes of generalized pruritus?
»	How prevalent is an underlying systemic disease in a patient who seeks medical attention for pruritus?
»	What is “winter itch”? In which patient population is it common?
»	The patient complains that “wool makes me itch” or “I am allergic to wool.” What disease does this patient probably have?
»	What treatment should the physician consider if a patient presents with pruritus and “hives”?
»	What disease should the physician consider if the patient volunteers that his spouse also suffers from itching?
»	Is pruritus in HIV-infected patients common? What are the common causes of pruritus in these patients?
»	Which psychiatric disorder often presents with intractable pruritus?
»	Which patients with renal failure experience “renal itch”?
»	Which patients with liver disease are most likely to experience pruritus? What is the best screening laboratory test?
»	What are the common causes of cholestic pruritus?
»	Which hematologic disorders are known to present with pruritus?
»	Is generalized pruritus a common symptom of endocrine disorders?
»	Can itching cause skin disease?
»	What is the best symptomatic treatment for a patient with pruritus?

What are the common causes of localized pruritus?

The differential diagnosis of localized pruritus should include dermatoses that are limited to certain parts of the body and those that are diffuse but have a predilection for these sites (Table 67-1)

Table 67-1. Differential Diagnosis of Localized Pruritus
	LOCATION	DISEASES
	Scalp	Psoriasis, seborrheic dermatitis
	Trunk	Contact dermatitis (axillae, waistline), erythrasma (axillae), psoriasis (periumbilical), notalgia paresthetica, scabies, seborrheic dermatitis, urticaria
	Inguinal region	Candida, contact dermatitis, erythrasma, overuse of topical steroids, pediculosis, scabies, tinea cruris
	Anal region	Candida, contact dermatitis, gonorrhea, hemorrhoids, pinworm, psoriasis, tinea cruris
	Hands	Contact dermatitis, scabies, eczema
	Legs	Atopic dermatitis (popliteal fossae), dermatitis herpetiformis (knees), lichen simplex chronicus (malleoli), neurotic excoriations, nummular eczema, stasis dermatitis
	Feet	Contact dermatitis, pitted keratolysis, tinea pedis