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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
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
• systemic disorders
• psychogenic
• habit / itch-scratch
• physiological?
Common itchy skin disorders in the young
Common itchy skin disorders in the young
• infestations: scabies, lice, threadworms
• eczemas
• urticaria
• psoriasis (sometimes)
• insect bites – papular urticaria
• pityriasis rosea
• viral exanthems
Common itchy skin disorders in the young
• infestations: scabies, lice, threadworms
• eczemas
• urticaria
• psoriasis (sometimes)
• insect bites – papular urticaria
• pityriasis rosea
• viral exanthems
Common itchy skin disorders in the young
• infestations: scabies, lice, threadworms
• eczemas
• urticaria
• psoriasis (sometimes)
• insect bites – papular urticaria
• pityriasis rosea
• viral exanthems
Common itchy skin disorders in the young
• infestations: scabies, lice, threadworms
• eczemas
• urticaria
• psoriasis (sometimes)
• insect bites – papular urticaria
• pityriasis rosea
• viral exanthems
Common itchy skin disorders in the young
• infestations: scabies, lice, threadworms
• eczemas
• urticaria
• psoriasis (sometimes)
• insect bites – papular urticaria
• pityriasis rosea
• viral exanthems
Common itchy skin disorders in the young
• infestations: scabies, lice, threadworms
• eczemas
• urticaria
• psoriasis
• insect bites – papular urticaria
• pityriasis rosea
• viral exanthems
Common itchy skin disorders in the young
• infestations: scabies, lice, threadworms
• eczemas
• urticaria
• psoriasis (sometimes)
• insect bites – papular urticaria
• pityriasis rosea
• viral exanthems
Common itchy skin disorders in mature adults
Common itchy skin disorders in mature adults
• infestations: scabies
• eczemas / nodular prurigo/ xerosis
• urticaria
• psoriasis (sometimes)
• lichen planus
• bullous pemphigoid
• polymorphic light eruption
Common itchy skin disorders in adults
• infestations: scabies
• eczemas / nodular prurigo/ xerosis
• urticaria
• psoriasis (sometimes)
• lichen planus
• bullous pemphigoid
• polymorphic light eruption
Common itchy skin disorders in adults
• infestations: scabies
• eczemas / nodular prurigo/ xerosis
• urticaria
• psoriasis (sometimes)
• lichen planus
• bullous pemphigoid
• polymorphic light eruption
Common itchy skin disorders in adults
• infestations: scabies
• eczemas /nodular prurigo/ xerosis
• urticaria
• psoriasis (sometimes)
• lichen planus
• bullous pemphigoid
• polymorphic light eruption
Common itchy skin disorders in adults
• infestations: scabies
• eczemas/ nodular prurigo/ xerosis
• urticaria
• psoriasis (sometimes)
• lichen planus
• bullous pemphigoid
• polymorphic light eruption
Common itchy skin disorders in adults
• eczemas / nodular prurigo/ xerosis
• urticaria
• psoriasis (sometimes)
• infestations: scabies
• lichen planus
• bullous pemphigoid
• polymorphic light eruption
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
• systemic 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
Management of itching
• There is no specific drug for itch
Management of itching
• keep looking for a cause
• avoid aggravating factors
temperature, humidity, bedding, clothing
• reduce damage from scratching
clothing, bandaging, cut nails
Management of itching
• 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
Management of itching
• topical agents
• gadgets
• systemic agents
• psychological interventions
Management of itching
• topical agents
• gadgets
• systemic agents
• psychological interventions
Systemic agents
• Opiod antagonists• Ondansetron• Rifampicin• Cholestyramine• Tricyclic antidepressants• Thalidomide• Phototherapy
• Antihistamines ?
Management of itching
• topical agents
• gadgets
• systemic agents
• psychological interventions
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