Pruritus Ani

Aka: Pruritus Ani, Perianal Pruritus, Anal Pruritus, Perianal Dermatitis

1. Epidemiology
   1. Pruritus Ani Prevalence: 1-5% of population in the United States
2. Causes: Perianal Pruritus
   1. 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
   2. 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
   3. 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)
   4. 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
   5. 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
3. Signs
   1. See Anorectal Exam
   2. Findings suggestive of cause of Perianal Pruritus
      1. Intertrigo
      2. Prolapsed Hemorrhoid
      3. Anal Fissure
      4. Anogenital Wart
      5. Anorectal Fistula
   3. Complications of chronic scratching
      1. Excoriations
      2. Perianal skin lichenification
4. Labs (as indicated based on history and exam)
   1. Pinworm Test
   2. Perianal Streptococcus culture
   3. Anal biopsy
      1. Indicated only in refractory cases without clear etiology
   4. STD testing (indicated for receptive anal intercourse history)
      1. Herpes Simplex Virus Testing
      2. Gonorrhea PCR
      3. Chlamydia PCR
5. Evaluation
   1. Initiate therapy (see below) and see for follow-up after 4-6 weeks
      1. Conservative therapy is effective in 89% of patients
   2. 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%)
   3. References
      1. Daniel (1994) Dis Colon Rectum 37(7):670-4 [PubMed]
6. Management
   1. Eliminate itch-scratch cycle (especially while asleep)
   2. 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)
   3. Perianal cleaning (gentle)
      1. Wash twice daily with water and sensitive soap
      2. Clean with handheld shower head, squirt bottle, sitz bath or bidet
   4. 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)
7. References
   1. Cohee (2020) Am Fam Physician 101(1):24-33 [PubMed]
   2. Fargo (2012) Am Fam Physician 85(6): 624-30 [PubMed]
   3. Lacy (2009) Curr Gastroenterol Rep 11(5): 413-9 [PubMed]
   4. Pfenninger (2001) Am Fam Physician 63(12):2391-8 [PubMed]