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?

Generalised Pruritus• Medications• Dermatological

conditions with subtle signs

• Systemic disease• Psychogenic• Aquagenic pruritus• Idiopathic

Localised Pruritus

• Brachioradial pruritus• Notalgia paraesthetica

Pruritus = Itchy skin in the absence of any obvious dermatological condition

• 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 creamthinly od increased to maximum qds over 2wks.Treat for 8 wksOr 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