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Pruritus Ani

Pruritus Ani is a topic covered in the 5-Minute Clinical Consult.

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Basics

Description

  • Intense anal/perianal itching and/or burning
  • Usually acute
  • Classified as idiopathic (primary) or secondary (~75% of cases) to anorectal pathology (1)

Epidemiology

Incidence
  • Uncommon, 1–5% of the general population (1)
  • Predominant age: 30 to 60 years (1)
  • Predominant sex: male > female (4:1) (1)

Prevalence
Difficult to estimate as often unreported; present in up to 2–3% of patients visiting primary care (2)

Etiology and Pathophysiology

  • Over 100 etiologies categorized by inflammatory, infectious, systemic, neoplastic, neuropathic, neurogenic, and psychogenic causes (3,4)
  • Pruritus may create an irresistible desire to scratch leading to a self-perpetuating itch–scratch–itch cycle.
  • Consider primary pruritus ani when no other demonstrable causes can be found, including:
    • Poor anal hygiene
    • Loose or leaking stool that makes hygiene difficult. Patients with abdominal ostomy bags typically do not complain of pruritus.
    • Internal sphincter laxity
  • Etiologies of secondary pruritus ani:
    • Inflammatory dermatologic diseases:
      • Allergic contact dermatitis (soaps, perfumes, or dyes in toilet paper, topical anesthetics, oral antibiotics)
      • Atopic dermatitis ± lichen simplex chronicus (patients also have asthma and/or eczema)
      • Psoriasis (lesions tend to be poorly demarcated, pale, and nonscaling)
      • Seborrheic dermatitis
      • Lichen planus (may be seen in patients with ulcerative colitis and myasthenia gravis)
      • Radiation dermatitis (3)
    • Colorectal/anorectal diseases: rectal prolapse, hemorrhoids, fissures or fistulas, chronic diarrhea/constipation, polyps
    • Infectious etiologies, may be sexually transmitted: bacteria (gonorrhea, chlamydia, syphilis), viruses (herpes simplex virus [HSV], condyloma acuminate from human papillomavirus [HPV], molluscum), parasites (pinworms, lice, scabies, or bed bugs), fungal (Candida, or dermatophytes like tinea); other bacteria (Staphylococcus aureus, β-hemolytic Streptococcus, Corynebacterium minutissimum [Erythrasma]) (3)
    • Malignancies: melanoma, basal cell/squamous cell carcinoma, colorectal cancer, leukemia, lymphoma, or (uncommon) the presenting symptom of Bowen or Paget disease
    • Mechanical factors: vigorous cleaning and scrubbing, tight-fitting clothes, synthetic undergarments
    • Systemic diseases (often presents as generalized pruritus): diabetes mellitus (most common), chronic liver disease, renal failure, hyperthyroidism, anemia
    • Chemical irritants: chemotherapy, diarrhea (often from antibiotic use)
    • Dietary elements (citrus, milk products, coffee, tea, cola, chocolate, beer, wine, tomatoes, nuts)
    • Psychogenic factors: anxiety–itch–anxiety cycle

Risk Factors

  • Obesity
  • Excess perianal hair growth, and/or perspiration
  • Underlying anorectal pathology
  • Underlying anxiety disorder
  • Caffeine intake has been correlated with symptoms.

General Prevention

  • Good perianal hygiene
  • Avoid mechanical irritation of skin (vigorous cleaning or rubbing with dry toilet paper or baby wipes, harsh soaps or perfumed products, excessive scratching with fingernails, or wearing tight/synthetic undergarments).
  • Minimize moisture in perianal area (absorbent cotton in anal cleft may help keep area dry).
  • Avoid laxative use (loose stool is an irritant).

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Citation

Stephens, Mark B., et al., editors. "Pruritus Ani." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2019. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116496/all/Pruritus_Ani.
Pruritus Ani. In: Stephens MB, Golding J, Baldor RA, et al, eds. 5-Minute Clinical Consult. 27th ed. Wolters Kluwer; 2019. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116496/all/Pruritus_Ani. Accessed April 24, 2019.
Pruritus Ani. (2019). In Stephens, M. B., Golding, J., Baldor, R. A., & Domino, F. J. (Eds.), 5-Minute Clinical Consult. Available from https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116496/all/Pruritus_Ani
Pruritus Ani [Internet]. In: Stephens MB, Golding J, Baldor RA, Domino FJ, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2019. [cited 2019 April 24]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116496/all/Pruritus_Ani.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Pruritus Ani ID - 116496 ED - Stephens,Mark B, ED - Golding,Jeremy, ED - Baldor,Robert A, ED - Domino,Frank J, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116496/all/Pruritus_Ani PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -