Pruritus, localised skin Flashcards
Probability diagnosis
Atopic dermatitis (eczema)
Contact dermatitis (irritant and allergic)
Urticaria
Insect bites/infestations
Psoriasis
Simple pruritus (cause not found)
Other disorders
Infection/infestations:
- scabies
- pediculosis (scalp, body, pubic)
- tinea cruris
- Candida intertrigo
- bed bugs
Non-infection:
- pityriasis rosea
- lichen planus
- dermatitis herpetiformis
- asteatosis (dry skin)
- prickly heat (miliaria/heat rash)
- Grover disease
- chilblains
- seborrhoeic dermatitis (usually mild)
Consider (rare):
- myeloproliferative disorders
- cutaneous T-cell lymphoma
Masquerades checklist
Depression
Diabetes
Drugs
Is the patient trying to tell me something?
Psychogenic including dermatitis artefacta.
Key history
Includes PMHx, especially
- chronic dermatoses (particularly atopic dermatitis and contact dermatitis)
- diabetes
- psychological disorders
Enquire about exposure to infestations such as;
- ‘backpacker’ lodgings
- scabies
- sexual contact.
Drug history is important.
Key examination
General and localised examination of the skin
Note any scratch marks
Look for evidence of insects such as;
- scabies
- lice
- bed bugs
Violaceous rash of lichen planus and the vesicles of dermatitis herpetiformis
Key investigations
FBE/ESR
Blood sugar
Microscopic examination of skin scrapings
Skin biopsy
Diagnostic tips
Pruritus is a feature of dry skin, common in the elderly.
An intense localised itch is suggestive of scabies or bed bugs.
