Pruritus

Rationale

Itching is common symptom. In the absence of primary skin lesions, generalized pruritus can be indicative of an underlying systemic disease, but itching in most cases is due to a cutaneous disorder.

Causal Conditions

(list not exhaustive)

1. Skin lesions
   1. Primary skin disease
      1. Blisters (e.g., dermatitis herpetiformis)
      2. Rash (e.g., psoriasis, lichen planus)
   2. Parasitosis (e.g., scabies, pediculosis)
   3. Allergy (e.g., eczema, allergic dermatitis, urticaria)
   4. Arthropod bites
   5. Factitious dermatitis
2. No skin lesions
   1. Dry skin
   2. Drugs/Foods
   3. Obstructive biliary disease
   4. Uremia/kidney injury
   5. Haematological
      1. Polycythemia vera/Microcytic anemia
      2. Leukemia
      3. Lymphoma
   6. Carcinoma/Carcinoid syndrome
   7. Endocrine (diabetes, thyroid disease)
3. Psychiatric/Emotional disorders

Key Objectives

Given a patient with pruritus, the candidate will differentiate excoriations due to scratching from primary skin lesions. The candidate will identify skin lesions if present. In their absence, the candidate will identify the underlying cause of pruritus.

Enabling Objectives

Given a patient with pruritus, the candidate will

1. list and interpret critical clinical findings, including
   1. results of an appropriate history, including an occupational history, and of a physical examination aimed at determining the cause of pruritus;
   2. differentiation of pruritus associated with skin lesions from that without primary skin disease;
   3. any primary skin lesions associated with the pruritus;
2. list and interpret critical investigations, including investigations to diagnose systemic disorders in the absence of skin lesions;
3. construct an effective plan of management, including
   1. providing local and other therapy for pruritus due to skin disease;
   2. initiating a therapy for pruritus due to an underlying systemic disease;
   3. initiating a referral for consideration of social issues related to infectious or parasitic causes;
   4. referring the patient for specialized care, if necessary.