itchy rashes maggie kirkup spr dermatology royal united hospital bath

Itchy rashes

Maggie Kirkup

SpR Dermatology

Royal United Hospital

Bath

How common is skin disease in the population?

1. Questionnaire - 1217 unselected adultsSkin accounted for 25% of 6009 ailments (Market Research Group 1982)

2. Examination - 55% of population had a skin complaint, 22.5% worthy of medical attention1.

1Rea et al Br J Prev Soc Med 1976; 30: 107-14

Describe itch

• “local discomfort or irritation of the skin, prompting the sufferer to scratch or rub the affected area. It is the main symptom of skin disease”

• “a peculiar tingling or uneasy irritation of the skin that causes a desire to scratch the affected area”

“It feels as though every nerve ending in my body is attacking me intensely at my ankles, feet, lower legs, neck, under the breasts (even the nipples tingle). It's absolutely horrendous! My hands grow red as a beet and the itching nearly takes the skin off my hands as I scratch.”

All Party Parliamentary Report on Impact of Skin Disease. 2003

“ It’s like someone tickling you under the skin”

Pathophysiology

• Debate continues over whether there are specific nerve endings for itch

• Possibly more than one mechanism

Pathophysiology of itch

• Free nerve endings Fibres most concentrated in wrists

and ankles Unmyelinated C fibres to dorsal

horn in spinal cord • Scratching is a spinal reflex

response Ascends to cerebral cortex via spinothalamic tract

• Skin inflammation

• Psychological concerns

• Chemical mediatorsSubstance POpioid and non-opioid peptidesSomatostatinNeurokinin AHistamineSerotoninProstaglandins

• External mediators

Environmental heat or dryness

http://www.fpnotebook.com/PHA78.htm

Approach to diagnosis of itching

• History

including onset, duration, pattern, effect on sleep, previous skin disease, contacts, other medical problems, drugs, response to treatment so far.

• Skin examination

features of rash, post-inflammatory changes, signs of scratching

• General examination

Signs of itching

• distress

• excoriation

• lichenification

• shiny nails

• weals

• nodules

Factors affecting presentation of itchy condition

• age

• self-control/ social setting/ distractions

• other medical conditions/ ability to scratch

• site of itch

• specific skin condition

• duration

Causes of itch

• skin disorders

• systemic disorders

• psychogenic

• habit / itch-scratch cycle

• physiological?

Causes of itch

• skin disorders


• psychogenic

• habit / itch-scratch

• physiological?

Common itchy skin disorders in the young


• infestations: scabies, lice, threadworms

• eczemas

• urticaria

• psoriasis (sometimes)

• insect bites – papular urticaria

• pityriasis rosea

• viral exanthems



• eczemas

• urticaria

• psoriasis



• viral exanthems



• eczemas

• urticaria




• viral exanthems

Common itchy skin disorders in mature adults

Common itchy skin disorders in mature adults

• infestations: scabies

• eczemas / nodular prurigo/ xerosis

• urticaria


• lichen planus

• bullous pemphigoid

• polymorphic light eruption

Common itchy skin disorders in adults



• urticaria


• lichen planus





• eczemas /nodular prurigo/ xerosis

• urticaria


• lichen planus





• eczemas/ nodular prurigo/ xerosis

• urticaria


• lichen planus





• urticaria



• lichen planus



Less common skin complaints which itch

• dermatitis herpetiformis

• aquagenic pruritus

• T cell lymphomas

• pityriasis rubra pilaris

• onchocerciasis etc etc

Localised itch

• Anogenital/ pruritus ani:

think of threadworms, lichen sclerosis, lice, scabies, contact dermatitis

• Hands:

eczemas, scabies, contact dermatitis

Localised itch

• Anogenital/ pruritus ani:

think of threadworms, lichen sclerosis, lice, contact dermatitis

• Hands:

eczemas, scabies, contact dermatitis

Localised itch

• Flexures: atopic/ seborrhoeic eczema, scabies

• Scalp: lice, seborrhoeic dermatitis, psoriasis

• Any area: discoid eczema, lichen simplex chronicus, contact dermatitis

Less common causes of localised itch

• brachioradial pruritus

• notalgia paraesthetica

Skin disorders which don’t (usually) itch

• psoriasis ?

• acne/ folliculitis

• vasculitis/purpura

• erythema multiforme

• secondary syphilis

Causes of itch

• skin disorders


• psychogenic

• habit

• physiological?

Systemic causes of itch

• liver disease

• renal failure

• iron deficiency

• metabolic:

protein, zinc, calcium, vitamin deficiencies

• thyroid disease

Systemic causes of itch (part 2)

• diabetes

• malignancies: lymphoma, PRV,

leukaemias, myeloma

• pregnancy

• neurological

• drugs

Screening investigations in itchy patients with no rash

• Full blood count

• Ferritin

• Renal function

• Liver function

• Thyroid function

• ? Chest X ray

Psychogenic itch

• epidemic forms - hysteria

• delusional parasitosis

• habit - itch/scratch cycle

Management of itching

• Treat the cause

• Treat the itch


• There is no specific drug for itch


• keep looking for a cause

• avoid aggravating factors

temperature, humidity, bedding, clothing

• reduce damage from scratching

clothing, bandaging, cut nails


• topical agents

• gadgets

• systemic agents

• psychological interventions

Topical agents• emollients• antihistamines* - doxepin (Xepin)• unknown mechanism -

crotamiton (Eurax)

calamine• counter-irritant - capsaicin, menthol• local anaesthetics *

• paste bandages *Risk sensitization


• topical agents

• gadgets

• systemic agents


Systemic agents

• Opiod antagonists• Ondansetron• Rifampicin• Cholestyramine• Tricyclic antidepressants• Thalidomide• Phototherapy

• Antihistamines ?


• topical agents

• gadgets

• systemic agents


Psychological and alternative interventions

• Biofeedback• Behaviour therapy*• Relaxation techniques• Acupuncture• Hypnotherapy• Homeopathy • Self-help groups*Melin I et al Behavioural treatment of scratching in patients with atopic dermatitis.

Brit J Dermatol 1986; 115: 467-74

Summary

• Itching can be caused by skin disease, systemic disease, psychogenic factors or idiopathic

• Management and investigation need to be tailored to the patient’s condition and circumstances

itchy rashes maggie kirkup spr dermatology royal united hospital bath

Documents

skin slide

common itchy skin disorders

young slide

common skin complaints

dryness slide

mechanism slide

unselected adults skin

previous skin disease