Essential Dermatology for GPs
The Itchy Patient
Lucy Scriven
• Itching may be due to an underlying skin
condition
– Eczemas
– Scabies, lice, threadworms
– Psoriasis (sometimes)
– Insect bites
– Exanthems
– Lichen planus
– Nodular prurigo
– Bullous pemphigoid
– Polymorphic light eruption
What’s this?
• Pompholyx
• PLE
• Bullous pemphigoid
• Eczema
• Lichen planus
• Psoriasis
• Scabies
• Papular urticaria
What if they are just itchy?
Pruritus = Itchy skin in the absence of any
obvious dermatological condition
Generalised Pruritus
Localised Pruritus
• Medications
• Dermatological
conditions with subtle
signs
• Systemic disease
• Psychogenic
• Aquagenic pruritus
• Idiopathic
• Brachioradial pruritus
• Notalgia paraesthetica
• Up to 50% of pts will have no clear cause
– idiopathic pruritus
• This should be a diagnosis of exclusion!
• So – we need a logical approach to try to
ascertain a cause.......
STEP 1: TAKE A CAREFUL HISTORY
• Onset, duration, pattern, effect on sleep, past
history of skin disease, contacts, response to
treatments so far
• Medications
– Opioids, Statins, ACEI, Digoxin
– Need to discontinue suspected drug for a few
weeks if possible
• Systemic disease
– Liver disease, renal failure, haematological
disorders, thyroid disease, paraneoplastic
• Localised Pruritus – 2 conditions which cause
localised areas of itching / burning
– Brachioradial pruritus - around elbow and
extensor surface of forearm
– Notalgia paraesthetica – mid-scapular area
– Consider capsaicin cream
thinly od increased to
maximum qds over 2wks.
Treat for 8 wks
Or try gabapentin or low
dose amitriptyline.
• Aquagenic pruritus
– Patients complain of intense pricking itch on
contact with water or change of skin
temperature
– Do not develop a rash
– Responds poorly to antihistamines
– May respond to phototherapy
STEP 2: EXAMINE THE PATIENT CLOSELY
– Dry skin / asteototic eczema
• Common cause, especially in the elderly in
winter
• Signs may be subtle
• FEEL the skin!
• Look closely for fine scale
– Excoriations
– Bruising
– Lichen simplex chronicus
• Asteototic eczema
• Excoriations
• ‘Butterfly’ distribution
• Lichen simplex chronicus
• Dermographic urticaria
– Should be reproducible
STEP 3 - ? SYSTEMIC DISEASE
– Liver disease, renal failure, haematological
disorders (e.g. Iron deficiency anaemia,
polycythaemia, Hodgkin’s lymphoma), thyroid
disease, paraneoplastic phenomena, pregnancy
– Thorough history and examination to include
checking for enlarged lymph nodes and
hepatosplenomegaly
• Screening investigations in pruritus
– Full blood count
– Ferritin
– CRP
– Routine biochemistry (U&E, LFT, bone, glucose)
– Thyroid function
– Antimitochondrial antibody (1 biliary cirrhosis)
– Urinalysis
– Chest X ray
– Consider immunoglobulins and plasma
electrophoresis in older pts
STEP 4 - ? PSYCHOGENIC
– Anxiety / depression can cause or be caused by
pruritus, esp in older pts
– Delusions of parasitosis
• Patient is convinced that a parasite / infestation
is living in their skin
• May bring inorganic matter to the consultation
• Excoriations often seen but nothing else – no
burrows, no urticated papules
• Idiopathic Pruritus
– No identifiable cause found in up to 50% pts
– Can cause persistent and widespread
itching and often extensive excoriation
– Common in 7th decade and beyond
Management
• Treat any underlying cause
• Provide a patient information leaflet
• General measures
– Liberal emollients if at all dry – keep in fridge
– Sedating antihistamines e.g. Hydroxyzine 25-50mg
nocte +/- 10mg tds through the day if required. Use
periodically as tolerance may develop
– Topical agents e.g. 1 or 2% menthol in Aqueous
cream, Eurax cream, Balneum Plus / Dermol
– Phototherapy may help in recalcitrant cases
• Manage any features of anxiety or depression
– Consider low dose amitriptyline (25-75mg nocte)
• If associated with hepatic or renal disease or
malignancy
– Can be difficult to treat
– Naltrexone and rifampicin have been reported as
helpful in renal disease
– Cholestyramine can be effective if secondary to
liver disease
• Avoid aggravating factors
• Reduce damage from scratching