Pruritus Ani

Epidemiology

Pruritus Ani Prevalence: 1-5% of population in the United States

Causes
Perianal Pruritus

Systemic causes
1. Diabetes Mellitus
2. Hyperbilirubinemia
3. Leukemia
4. Lymphoma
5. Aplastic Anemia
6. Thyroid disease
7. Lumbosacral Radiculopathy (especially elderly)
8. Inflammatory Bowel Disease
Functional and mechanical causes
1. Chronic Diarrhea
2. Chronic Constipation
3. Anal Fissure
4. Anal Fistula
5. Tight fitting clothes
6. Vigorous peri-anal cleaning
7. Stool Leakage
  1. Anal Incontinence
  2. Prolapsed Hemorrhoids
  3. Rectal Prolapse
  4. Anal papilloma (HPV)
  5. Skin Tags
Infections
1. Perianal Streptococcal Cellulitis
2. Erythrasma (Corynebacterium)
3. Intertrigo (Candida)
4. Herpes Simplex Virus (HSV)
5. Human Papillomavirus (HPV)
6. Pinworms or Enterobius (Especially young children)
7. Scabies
8. Perirectal Abscess
9. Gonorrhea
10. Syphilis
11. Molluscum Contagiosum
12. Condyloma (Anogenital Wart)
Dermatologic causes (Perianal Dermatitis)
1. Psoriasis
2. Contact Dermatitis (see below)
3. Hidradenitis Suppurativa
4. Seborrheic Dermatitis
5. Intertrigo
6. Neurodermatitis
7. Bowen Disease or Squamous Cell Carcinoma
8. Extramammary Paget Disease
9. Atopic Dermatitis
10. Lichen Planus
11. Lichen Sclerosis
Exposures
1. Systemic: Medications
  1. Colchicine
  2. Quinidine
  3. Neomycin
  4. Chemotherapy
2. Topicals: Contact Dermatitis
  1. Soaps, deodorants or perfumes
  2. Alcohol-based anal wipes
  3. Allergy to dyes or perfumes in toilet paper
  4. Fabric softener use
  5. Talcum powder
  6. Suppositories
3. Topicals: Food irritants
  1. Tomatoes
  2. Chili peppers
  3. Caffeinated beverages
  4. Beer
  5. Citrus juices or fruit
  6. Milk products

Signs

See Anorectal Exam
Findings suggestive of cause of Perianal Pruritus
1. Intertrigo
2. Prolapsed Hemorrhoid
3. Anal Fissure
4. Anogenital Wart
5. Anorectal Fistula
Complications of chronic scratching
1. Excoriations
2. Perianal skin lichenification

Labs (as indicated based on history and exam)

Pinworm Test
Perianal Streptococcus culture
Anal biopsy
1. Indicated only in refractory cases without clear etiology
STD testing (indicated for receptive anal intercourse history)

Evaluation

Initiate therapy (see below) and see for follow-up after 4-6 weeks
1. Conservative therapy is effective in 89% of patients
Failure to improve (11% of cases) should prompt further evaluation for underlying cause
1. Contributory underlying anorectal disease (52%)
2. Lower endoscopy abnormality (35%)
3. Underlying neoplasm (23%)
References
1. Daniel (1994) Dis Colon Rectum 37(7):670-4 [PubMed]

Management

Eliminate itch-scratch cycle (especially while asleep)
Eliminate exacerbating factors (see causes above)
1. Critical to keep the perianal area dry
2. Avoid excessive wiping and Alcohol wipes (and other topical irritants)
3. Wear loose clothing
4. Dietary changes (eliminate coffee, milk, beer, nuts)
5. Topical barrier Emollient (e.g. vaseline)
Perianal cleaning (gentle)
1. Wash twice daily with water and sensitive soap
2. Clean with handheld shower head, squirt bottle, sitz bath or bidet
Medications
1. Hydroxyzine (Atarax or Vistaril) 50 mg at bedtime (adults)
  1. Avoid in the elderly (see Beers List)
2. Topical 5% Lidocaine (Xylocaine) ointment
  1. Avoid prolonged use
3. Low potency Topical Corticosteroid
  1. Use briefly as last resort only
  2. Hydrocortisone 1% applied to area for up to 2 weeks
  3. Avoid high potency Corticosteroids
  4. Avoid use longer than 4 weeks
  5. Al-Ghaniem (2007) Int J Colorectal Dis 22(12):1463-7 [PubMed]
4. Capsaicin 0.006% cream
  1. Requires compounding - dilute standard Capsaicin in white paraffin
  2. Lysy (2003) Gut 52(9): 1323-6 [PubMed]
5. Tacrolimus 0.1% (Protopic)

References