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