Pruritus, Anogenital

Essentials of Diagnosis

• Anogenital itching, chiefly nocturnal

• Skin findings are highly variable, ranging from none to excoriations and inflammation of any degree, including lichenification

General Considerations

• May be due to

  • Intertrigo

  • Psoriasis

  • Lichen simplex chronicus

  • Seborrheic or contact dermatitis (from soaps, colognes, douches, and various topical treatments)

  • Irritating secretions (eg, diarrhea, leukorrhea, or trichomoniasis)

  • Local disease (candidiasis, dermatophytosis, erythrasma) and, at times, oxyuriasis (pinworm infestation)

• In pruritus ani, hemorrhoids are often found, and leakage of mucus and bacteria from the distal rectum onto the perianal skin may be important in cases in which no other skin abnormality is found

• In women, pruritus vulvae does not usually involve the anal area, though anal itching usually spreads to the vulva

• In men, pruritus of the scrotum is most commonly seen in the absence of pruritus ani

• Up to one-third of causes of anogenital pruritus may be due to nerve root impingements in the lumbosacral spine

• Squamous cell carcinoma of the anus and extramammary Paget disease are rare causes of genital pruritus

Symptoms and Signs

• The only symptom is itching

• Physical findings are usually not present, but there may be

  • Erythema

  • Fissuring

  • Maceration

  • Lichenification

  • Excoriations

  • Changes suggestive of candidiasis or tinea

Differential Diagnosis

• Idiopathic

• Intertrigo

• Psoriasis

• Hemorrhoids

• Lichen simplex chronicus

• Seborrheic dermatitis

• Contact dermatitis

• Candidiasis

• Tinea

• Erythrasma

• Irritants: diarrhea, vaginal discharge

• Lichen sclerosis

• Oxyuriasis

Laboratory Tests

• Urinalysis and blood glucose testing may lead to a diagnosis of diabetes mellitus

• Microscopic examination or culture of tissue scrapings may reveal yeasts or fungi

• Stool examination may show pinworms

Imaging Studies

• Radiologic studies (CT or MRI) may demonstrate nerve root impingements in the lumbosacral spine

Medications

GENERAL MEASURES

• Treating constipation, preferably with high-fiber management (psyllium), may help

LOCAL MEASURES

• Pramoxine cream or lotion or hydrocortisone-pramoxine (Pramosone), 1% or 2.5% cream, lotion, or ointment is helpful in managing pruritus in the anogenital area; the ointment or cream should be applied after a bowel movement

• Topical doxepin cream 5% is similarly effective, but it may be sedating

• The use of strong corticosteroids on the scrotum may lead to persistent severe burning on withdrawal of the drug

• Balneol Perianal Cleansing Lotion, or Tucks premoistened pads, ointment, or cream may be very useful for pruritus ani

• In men with scrotal or anal pruritus, capsaicin cream 0.006% twice daily may be beneficial

• In cases where underlying spinal neurologic disease is suspected, gabapentin or pregabalin may be helpful

Therapeutic Procedures

• Instruct the patient to use very soft or moistened tissue or cotton after bowel movements and to clean the perianal area thoroughly with cool water if possible

• Women should use similar precautions after urinating

• Patch testing most commonly reveals clinically relevant allergy in about 20% of patients, often to methylchloroisothiazoline/methylisothiazoline, a preservative commonly found in "baby wipes" and other personal care products

• Underclothing should be changed daily, and in men, the seam of their "boxers" should not rub against or contact the scrotum

Prognosis

• Although benign, anogenital pruritus is often persistent and recurrent

Prevention

• Instruct the patient in proper anogenital hygiene after treating systemic or local conditions

When to Refer

• If there is a question about the diagnosis, if recommended therapy is ineffective, or if specialized treatment is necessary