Pruritus

Generalised pruritus 

May occur without any underlying skin disease. Xerosis/dry skin in the elderly is one of the commonest caused of itch. 

In the absence of overt skin disease consider an underlying diagnosis  such as: 

• Diabetes mellitus 
• Anaemia / Iron deficiency 
• Thyroid dysfunction 
• Liver disease 
• Medication induced (ie opiates) 

Rarely: 

• Haematological malignancy eg Lymphoma 
• Other malignancies 
• Psychogenic itch 
• HIV 

Vulval and perianal pruritus 

Consider the following diagnoses: 

• Candidiasis 
• Dermatophyte infection 
• Irritant dermatitis or allergic contact dermatitis 
• Lichen simplex 
• Lichen sclerosis 
• Infestation with thread worms 
• Intra-epithelial neoplasia — ask about previous history of anogenital warts or cervical intra-epithelial neoplasm

Dermatology Referral Criteria 

Generalised pruritus 

• Unresponsive to management 
• Diagnostic uncertainty 

Vulval and perianal pruritus 

• Diagnosis uncertainty 
• Uncontrolled symptoms 
• If contact allergy suspected 

Generalised pruritus Treat any underlying disease Regular emollient and soap substitutes Oral antihistamines (sedating type may be more helpful in itch) Consider menthol in aqueous cream (0.5%- 2%) 

Investigations as appropriate 

• Glucose 
• Renal Function 
• Full blood count 
• Ferritin 
• Liver Function tests 
• Thyroid Function tests 
• Medication review 

If indicated by history 

• Chest x-ray 
• Abdominal ultrasound 
• HIV test 

Vulval and perianal pruritus Investigations as appropriate 

• Urinalysis for glycosuria 
• Swab for yeasts 
• Stool sample for ova and parasites 

Management 

• Emollients, soap substitutes and avoidance of irritants 
• Treat the underlying disease where applicable 
• Mild / moderate steroid plus antifungal / antibacterial 
• Potent topical steroid may be required for limited period in lichen simplex and lichen sclerosis 

• NHS Inform: www.nhsinform.scot 
• British Association of Dermatologists: http://www.bad.org.uk/for-the-public/patient-information-leaflets 
• Dermnet NZ: http://www.dermnetnz.org/ 
• Primary Care Dermatological Society: http://www.pcds.org.uk/