M62 Course – Cedar Court Hotel, Huddersfield 7th April 2005

The Dermatologist and Pruritus Ani

MJ Harries and CEM GriffithsDermatology Centre, Hope Hospital,

Manchester, UK

“An unpleasant cutaneous sensation that induces the desire

to scratch the skin”

Itch-Scratch Cycle

PRURITUS

SCRATCHING

DAMAGED PERIANAL SKIN

Yosipovitch et al. Lancet 2003; 361:690-694

Classification of Itch

Pruritoceptive itchOriginates in the skin

Neurogenic itchOriginates in the

nervous system

Itch specific neuronal pathway (C-fibres and spinothalamic tracts)

Causes of Pruritus Ani

Anal pathology

Infections

Skin disease

Contact allergy

Underlying medical conditions

Idiopathic

Causes of Pruritus Ani

Anal pathology

Infections

Skin disease

Contact allergy

Underlying medical conditions

Idiopathic

Skin Disease

85% consecutive patients referred to a combined colorectal and dermatological clinic had an underlying dermatosis

Over half had a positive patch test

“Patients with long-standing pruritus ani with no other symptoms to suggest colorectal pathology should be referred to a dermatologist for assessment and patch testing.”

Dasan et al. Br J Surg 1999; 86: 1337-40

Psoriasis

2% population

Approx. 1.2 million sufferers in the UK

Immune-mediated disease

Positive family history common

Psoriasis

Symmetrical

Extensor aspectsElbows / kneesScalpUmbilicusNatal cleft

44% perianal involvement

Farber et al. Dermatologica 1974;148:1-18

Psoriasis - Perianal

Psoriasis - Perianal

Where else to look?

Where else to look?

Lichen Planus

Idiopathic inflammatory disease of the skin and mucous membranes

Common sitesFlexor wristAnterior lower legNeckPresacral area

75% oral involvement

Lichen Planus

Polygonal, violaceous, flat-topped papules

Wickham’s striae

Pruritus +++

Lichen Planus - Perianal

Lichen Planus - Perianal

Where else to look?

Where else to look?

Lichen Sclerosis

Idiopathic inflammatory disease that preferentially affects the anogenital region

Hypopigmented and atrophic skin

Figure-of-eight distribution (women)

5% risk of SCC

Lichen Sclerosis - Perianal

Seborrheic Eczema

Link with sebum overproduction and the commensal yeast Malassezia furfur

Red-brown patches with “greasy” scale

Common sitesScalpNasolabial foldsCentral chest / backFlexures

Where else to look?

Lichen Simplex – The Itch that rashes

Itching often localised to one site resulting in lichenification

Itch / scratch cycle develops

Common sitesPerineum Scrotum / vulvaPosterior neckLateral lower legs

Lichen Simplex - Perianal

Allergic Contact Dermatitis

55 / 80 (69%) clinically relevant allergic reactions

38 of these reactions to medicaments or their constituents

Improvement or resolution of symptoms in ¾ patients with avoidance advice

Advise patch testing at an early stage Harrington et al. BMJ 1992; 305: 955

Eczema - Perianal

Patch Test

Common allergens placed into Finn chambers 35 common allergens

tested in the BCDS standard series

Extra allergens tested in the perineal series

Type IV delayed hypersensitivity response

Patch Test – 0h

Patch Test – 48h

Patch Test – 96h

Grading system for reactions

- Negative

+/- Doubtful

+ Weak

++ Strong

+++ Very strong

Common Perianal Allergens

Local anaesthetics Corticosteroids Neomycin Perfume Preservatives Antiseptics

Goldsmith et al. Contact Dermatitis 1997; 36: 174-5

Pruritus Ani and Underlying Medical Conditions

Consider a “pruritus screen” if generalised itch is also present

Common causes include Iron deficiency Renal failure Hepatic/ biliary disease Malignancy

FBC Ferritin / serum Fe / % sat /

TIBC ESR U&E LFT TFT Glucose Calcium Serum electrophoresis CXR

Idiopathic Pruritus Ani

Faecal contamination Difficulty in cleaning the area Anal sphincter dysfunction

Farouk et al. Br J Surg 1994; 81: 603-606

Dietary causes

Lumbosacral radiculopathy 16 / 18 (80%) lubosacral radiculopathy confirmed by N.C.S Paravertebral injections of steroid / lignocaine resulted in

reduced pruritus

Cohen et al. J Am Acad Dermatol 2005; 52 :61-6

Treatment - General Advice

Wash after every B.O and twice a day

Avoid irritants

Keep the area dry

Wear cotton underwear

Keep bowels regularAlexander-Williams J. BMJ 1983;287:1528

Topical Steroids

Mild, moderate, potent and very potentTreats inflammation Break the itch-scratch cycle

As control is achieved the potency should be reduced

If not improving consider?Appropriate potency for condition?steroid allergy – Patch test?correct diagnosis - Biopsy

Other Treatments

Topical CapsaicinPlacebo controlled trial0.006% capsaicin cream t.d.s for 4 weeks 31 / 44 (70%) responded

Lysy et al. Gut 2003; 52: 1323 – 1326

Intradermal methylene blue injections1% methylene blue / hydrocortisone / lignocaine88% patients responded

Botterill et al. Colorectal Dis 2002;4:144-6

Summary

Examine the entire skin surface including nails and mucous membranes

Consider patch testing early in management

Consider skin biopsy if any diagnostic doubt or if the condition is not responding to appropriate treatment