Itchy rashes

1
Itchy rashes

• Maggie Kirkup
• SpR Dermatology
• Royal United Hospital
• Bath

2
How common is skin disease in the population?

• Questionnaire - 1217 unselected adultsSkin
  accounted for 25 of 6009 ailments (Market
  Research Group 1982)
• 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
3
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

4

• 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

5

• Its like someone tickling you under the skin

6
Pathophysiology

• Debate continues over whether there are specific
  nerve endings for itch
• Possibly more than one mechanism

7
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 mediators
• Substance P
• Opioid and non-opioid peptides
• Somatostatin
• Neurokinin A
• Histamine
• Serotonin
• Prostaglandins
• External mediators
• Environmental heat or dryness

8
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

9
Signs of itching

• distress
• excoriation
• lichenification
• shiny nails
• weals
• nodules

10
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

11
Causes of itch

• skin disorders
• systemic disorders
• psychogenic
• habit / itch-scratch cycle
• physiological?

12
Causes of itch

• skin disorders
• systemic disorders
• psychogenic
• habit / itch-scratch
• physiological?

13
Common itchy skin disorders in the young
14
Common itchy skin disorders in the young

• infestations scabies, lice, threadworms
• eczemas
• urticaria
• psoriasis (sometimes)
• insect bites papular urticaria
• pityriasis rosea
• viral exanthems

15
Common itchy skin disorders in the young

• infestations scabies, lice, threadworms
• eczemas
• urticaria
• psoriasis (sometimes)
• insect bites papular urticaria
• pityriasis rosea
• viral exanthems

16
Common itchy skin disorders in the young

• infestations scabies, lice, threadworms
• eczemas
• urticaria
• psoriasis (sometimes)
• insect bites papular urticaria
• pityriasis rosea
• viral exanthems

17
Common itchy skin disorders in the young

• infestations scabies, lice, threadworms
• eczemas
• urticaria
• psoriasis (sometimes)
• insect bites papular urticaria
• pityriasis rosea
• viral exanthems

18
Common itchy skin disorders in the young

• infestations scabies, lice, threadworms
• eczemas
• urticaria
• psoriasis (sometimes)
• insect bites papular urticaria
• pityriasis rosea
• viral exanthems

19
Common itchy skin disorders in the young

• infestations scabies, lice, threadworms
• eczemas
• urticaria
• psoriasis
• insect bites papular urticaria
• pityriasis rosea
• viral exanthems

20
Common itchy skin disorders in the young

• infestations scabies, lice, threadworms
• eczemas
• urticaria
• psoriasis (sometimes)
• insect bites papular urticaria
• pityriasis rosea
• viral exanthems

21
Common itchy skin disorders in mature adults
22
Common itchy skin disorders in mature adults

• infestations scabies
• eczemas / nodular prurigo/ xerosis
• urticaria
• psoriasis (sometimes)
• lichen planus
• bullous pemphigoid
• polymorphic light eruption

23
Common itchy skin disorders in adults

• infestations scabies
• eczemas / nodular prurigo/ xerosis
• urticaria
• psoriasis (sometimes)
• lichen planus
• bullous pemphigoid
• polymorphic light eruption

24
Common itchy skin disorders in adults

• infestations scabies
• eczemas / nodular prurigo/ xerosis
• urticaria
• psoriasis (sometimes)
• lichen planus
• bullous pemphigoid
• polymorphic light eruption

25
Common itchy skin disorders in adults

• infestations scabies
• eczemas /nodular prurigo/ xerosis
• urticaria
• psoriasis (sometimes)
• lichen planus
• bullous pemphigoid
• polymorphic light eruption

26
Common itchy skin disorders in adults

• infestations scabies
• eczemas/ nodular prurigo/ xerosis
• urticaria
• psoriasis (sometimes)
• lichen planus
• bullous pemphigoid
• polymorphic light eruption

27
Common itchy skin disorders in adults

• eczemas / nodular prurigo/ xerosis
• urticaria
• psoriasis (sometimes)
• infestations scabies
• lichen planus
• bullous pemphigoid
• polymorphic light eruption

28
Less common skin complaints which itch

• dermatitis herpetiformis
• aquagenic pruritus
• T cell lymphomas
• pityriasis rubra pilaris
• onchocerciasis etc etc

29
Localised itch

• Anogenital/ pruritus ani
• think of threadworms, lichen sclerosis, lice,
  scabies, contact dermatitis
• Hands
• eczemas, scabies, contact dermatitis

30
Localised itch

• Anogenital/ pruritus ani
• think of threadworms, lichen sclerosis, lice,
  contact dermatitis
• Hands
• eczemas, scabies, contact dermatitis

31
Localised itch

• Flexures
• atopic/ seborrhoeic eczema, scabies
• Scalp
• lice, seborrhoeic dermatitis, psoriasis
• Any area
• discoid eczema, lichen simplex chronicus,
  contact dermatitis

32
Less common causes of localised itch

• brachioradial pruritus
• notalgia paraesthetica

33
Skin disorders which dont (usually) itch

• psoriasis ?
• acne/ folliculitis
• vasculitis/purpura
• erythema multiforme
• secondary syphilis

34
Causes of itch

• skin disorders
• systemic disorders
• psychogenic
• habit
• physiological?

35
Systemic causes of itch

• liver disease
• renal failure
• iron deficiency
• metabolic
• protein, zinc, calcium, vitamin deficiencies
• thyroid disease

36
Systemic causes of itch (part 2)

• diabetes
• malignancies lymphoma, PRV,
• leukaemias, myeloma
• pregnancy
• neurological
• drugs

37
Screening investigations in itchy patients with
no rash

• Full blood count
• Ferritin
• Renal function
• Liver function
• Thyroid function
• ? Chest X ray

38
Psychogenic itch

• epidemic forms - hysteria
• delusional parasitosis
• habit - itch/scratch cycle

39
Management of itching

• Treat the cause
• Treat the itch

40
Management of itching

• There is no specific drug for itch

41
Management of itching

• keep looking for a cause
• avoid aggravating factors
• temperature, humidity, bedding, clothing
• reduce damage from scratching
• clothing, bandaging, cut nails

42
Management of itching

• topical agents
• gadgets
• systemic agents
• psychological interventions

43
Topical agents

• emollients
• antihistamines - doxepin (Xepin)
• unknown mechanism -
• crotamiton (Eurax)
• calamine
• counter-irritant - capsaicin, menthol
• local anaesthetics
• paste bandages Risk sensitization

44
Management of itching

• topical agents
• gadgets
• systemic agents
• psychological interventions

45
Management of itching

• topical agents
• gadgets
• systemic agents
• psychological interventions

46
Systemic agents

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

• Antihistamines ?

47
Management of itching

• topical agents
• gadgets
• systemic agents
• psychological interventions

48
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

49
Summary

• Itching can be caused by skin disease, systemic
  disease, psychogenic factors or idiopathic
• Management and investigation need to be tailored
  to the patients condition and circumstances