Pruritus ani Flashcards
Probability diagnosis
Chronic dermatitis + ‘itch-scratch’ cycle + stress
Seborrhoeic dermatitis (esp.), eczema
Antibiotic treatment
Contact dermatitis: clothing and perfumed toiletries
Irritation from excessive moisture and faecal discharge/soiling (esp. elderly)
Serious disorders not to be missed
Crohn disease
Anorectal carcinoma
Extramammary Paget disease
Sexually transmitted infections, e.g. syphilis
Other disorders
Candidiasis
Tinea cruris
Pinworm (threadworm) (esp. children)
Psoriasis (look for fissures in natal cleft)
Overzealous hygiene (e.g. OCD)
Post-diarrhoea esp. chronic or recurrent
Local anorectal conditions (e.g. piles, fissures, fistulas, skin tags, warts)
Masquerades checklist
Depression
Diabetes
Drugs (esp. antibiotics)
Is the patient trying to tell me something?
Psychological factors:
- stress and anxiety
- fear of cancer
Key history
This includes past history, especially;
- chronic dermatoses (esp. seborrhoeic dermatitis and contact dermatitis)
- diabetes
- chronic diarrhoea (e.g. Crohn disease, coeliac disease)
- psychological disorders
Enquire about lifestyle factors such as;
- excessive sweating
- sports activity
- habit scratching
Key examination
General inspection of skin and anorectal area.
Skin changes can vary from;
- minimal signs to
- marked pathology that can show;
- linear ulceration
- maceration
- lichenification
A full anorectal examination is necessary
Key investigations
Blood glucose
Urinalysis
Local skin scrapings and microscopy to detect organisms
Stool examination (for ova and parasites)
Diagnostic tips
Pruritus ani is worse;
- at night
- during hot weather
- after exercise
It is seen typically in adult males with considerable inner drive, often at times of stress and in hot weather when sweating is excessive.
In children pinworm infestation should be suspected.
