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Approach to a Patient with Pruritus

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DEFINITION

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CLASSIFICATION (IFSI 2007)

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HISTORY

1. Characteristics of Itch

• Onset — acute (days–weeks) vs. chronic (≥6 weeks)
• Duration and course — continuous, episodic, progressive
• Location — localized (scalp, anogenital, forearm) vs. generalized
• Severity — Numerical Rating Scale (NRS 0–10) or Visual Analogue Scale (VAS)
• Quality — burning, stinging, tickling (neuropathic); crawling sensation (parasitophobia)
• Time pattern — nocturnal (scabies, AD); aquagenic (polycythemia vera, mastocytosis); postbath

2. Aggravating/Relieving Factors

• Heat, sweating, friction, woolen clothing (AD)
• Water contact (aquagenic pruritus)
• Relief with ice packs (brachioradial pruritus — a neuropathic clue)
• Sunlight exposure (photodermatoses)

3. Associated Symptoms

• Skin rash (nature and distribution)
• Jaundice, dark urine, pale stools → cholestatic disease
• Weight loss, night sweats, lymphadenopathy → lymphoma/malignancy
• Polydipsia, polyuria → diabetes mellitus
• Fatigue, cold intolerance, hair loss → thyroid disease
• Burning/tingling with normal skin → neuropathic

4. Drug History

• Opioids (μ-receptor-mediated itch), ACE inhibitors, hydroxyurea, chloroquine, statins, calcium channel blockers — any recent medication change?

5. Personal & Family History

• Atopy (AD, asthma, allergic rhinitis)
• Chronic kidney disease, liver disease, HIV

6. Social History

• Contacts with similar itch (scabies)
• Travel history (parasitic infestations)
• Occupation (fiberglass dermatitis)
• Pregnancy (intrahepatic cholestasis of pregnancy, pruritic urticarial papules and plaques of pregnancy [PUPPP])

7. Quality of Life

• Sleep disturbance, anxiety, depression (ItchyQol questionnaire)

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EXAMINATION

A. Dermatological Examination

• Excoriations, prurigo papules/nodules, lichenification, hyperpigmented scars, linear streaks
• Their distribution is a clue (e.g., sparing the mid-back "butterfly sign" = notalgia paresthetica; linear dorsolateral forearm = brachioradial pruritus)

• Jaundice, hepatosplenomegaly, ascites → hepatic/cholestatic
• Pallor, excoriations without primary lesions + uraemic frost → CKD
• Lymphadenopathy + night sweats → lymphoma
• Thyroid enlargement, exophthalmos, pretibial myxedema → thyroid
• Dermographism → urticaria/mastocytosis
• "Butterfly sign" (mid-back spared in CKD pruritus — patient cannot reach)

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INVESTIGATIONS

Initial Baseline Work-up (for generalized pruritus without primary skin lesion):

Second-line Work-up (if initial is normal or guided by suspicion):

Key principle: Chronic progressive generalized pruritus without primary skin lesions should always prompt systemic workup, even though no single clinical feature reliably predicts a systemic etiology.

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TREATMENT

I. General / Non-pharmacological Measures

• Identify and treat underlying cause
• Lukewarm baths, avoid hot water (vasodilatory)
• Fragrance-free emollients liberally (restore barrier)
• Cotton clothing; avoid wool/synthetic
• Nail trimming (prevent excoriation)
• Cool environmental temperature, fan
• Avoidance of triggers (irritants, allergens)

II. Topical Therapy

III. Systemic Therapy

IV. Phototherapy

• NB-UVB — CKD pruritus (80–90% response), HIV-associated pruritus, CTCL, prurigo nodularis
• PUVA — aquagenic pruritus, polycythemia vera, CTCL
• UVA-1 — AD, mastocytosis

In CKD pruritus, phototherapy acts systemically — unilateral exposure relieves pruritus bilaterally.

V. Psychological Approaches

• Group psychotherapy, CBT (habit-reversal training)
• Biofeedback, acupuncture
• Treat comorbid anxiety and depression

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PREVALENCE SNAPSHOT (Selected Conditions)

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SUMMARY FLOW

Pruritus
    │
    ├─ Primary skin lesion present?
    │       YES → Treat underlying dermatosis
    │       NO ↓
    │
    ├─ Thorough history + examination
    │
    ├─ Baseline investigations (CBC, LFT, KFT, TFT, RBS, HIV)
    │
    ├─ Systemic cause found? → Treat cause + symptomatic antipruritic
    │
    ├─ Neuropathic features? → Neuroimaging + gabapentin/pregabalin
    │
    ├─ Psychological cause? → CBT + SSRIs
    │
    └─ Unknown (15%) → Empirical therapy + longitudinal follow-up

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