|Other names||Pruritus ani, pruritus anii, itchy anus, anal itching|
|Specialty||Dermatology, general surgery|
|Complications||Skin breakdown, thickening of the skin, infections|
|Causes||Skin diseases: Dermatitis, hidradenitis suppurativa, psoriasis, lichen planus, lichen sclerosis|
Infections: Pinworms, candidiasis, tinea cruris, trichomoniasis, gonorrhea, chlamydia
Anorectal disorders: Hemorrhoids, anal fistula, anal fissure
Cancers: Acanthosis nigricans, basal cell carcinoma, leukemia
Other diseases: Diabetes, liver disease, kidney failure
Perianal itching, also known as pruritus ani, is an irritation of the skin at the exit of the rectum, causing the desire to scratch. Scratching, in turn, makes the itching worse. Scratching may also result in skin breakdown, thickening of the skin over time, or infections.
While many cases occur due to an unknown cause, in 10% to 75% an underlying condition is present. Conditions may include skin diseases, infections, anorectal disorders, cancers, or systemic diseases. Skin diseases include dermatitis, hidradenitis suppurativa, psoriasis, lichen planus, and lichen sclerosis. Infections may include pinworms, candidiasis, tinea cruris, trichomoniasis, gonorrhea, and chlamydia. Anorectal disorders may include hemorrhoids, anal fistula, and anal fissures. Systemic diseases may include diabetes, liver disease, and kidney failure.
Treatment involves avoiding or treating the underlying cause. Keeping the area clean and dry is also recommended. Use of soap on the area is discouraged. Hydrocortisone cream may be recommended for a short period. It is estimated that 1% to 5% of the population is affected. Males are more commonly affected than females and it most commonly affects those in their 40s to 60s. The condition has been described since around 1200 BC in the Chester Beatty Medical Papyrus.
If a specific cause for pruritus ani is found it is classified as "secondary pruritus ani". If a specific cause is not found it is classified as "idiopathic pruritus ani".
Certain foods may also cause problems such as coffee, tomatoes, beer, citrus fruit, and milk products.
Abnormal passageways (fistulas) from the small intestine or colon to the skin surrounding the anus can form as a result of disease (such as Crohn's disease), acting as channels which may allow leakage of irritating fluids to the anal area.
Some diseases increase the possibility of yeast infections, such as diabetes mellitus or HIV infection. Treatment with antibiotics can bring about a disturbance of the natural balance of intestinal flora, and lead to perianal thrush, a yeast infection affecting the anus.
Some authorities describe “psychogenic pruritus” or "functional itch disorder", where psychological factors may contribute to awareness of itching.
Aside from diseases relative to the condition, a common view suggests that the initial cause of the itch may have passed, and that the illness is in fact prolonged by what is known as an itch-scratch-itch cycle. Scratching the itch encourages the release of inflammatory chemicals, which worsen redness, intensifies itchiness and increases the area covered by dry skin, thereby causing a snowball effect.
Diagnosis is usually done with a careful examination of the anus and the patient's history. If the presentation or physical findings are atypical, biopsies can be done.
In case of long-lasting symptoms, above all in patients over 50 years of age, a colonoscopy is useful to rule out a colonic polyp or tumor, that can show pruritus ani as first symptom.
The goal of treatment is asymptomatic, intact, dry, clean perianal skin with reversal of morphological changes. For pruritus ani of unknown cause treatment typically begins with measures to reduce irritation and trauma to the perianal area. Stool softeners can help prevent constipation. If this is not effective topical steroids or injected methylene blue may be tried. Another treatment option that has been met with success in small-scale trials is the application of a very mild (.006) topical capsaicin cream. This strength cream is not typically commercially available and therefore must be diluted by a pharmacist or end-user. If the itchiness is secondary to another condition such as infection or psoriasis these are typically treated.
A successful treatment option for chronic idiopathic pruritus ani has been documented using a clean, dry and apply (if necessary) method. The person is instructed to follow this procedure every time the urge to scratch occurs. The treatment makes the assumption that there is an unidentified bacteria in the feces that causes irritation and itching when the feces makes contact with the anal and perianal skin during defecation, flatulation or anal leakage (particularly during sleep).
Cleaning the area with warm water, avoiding all soaps and even baby wipes, then drying the area, ideally with a hair dryer to avoid irritation or failing that simply patting gently with a clean, dry, towel. If persons with pruritus ani do not need to scratch after these steps they are instructed to do nothing else. If the urge to scratch is still present they are instructed to apply a topical steroid cream which has antibiotic and antifungal properties. This will address a skin condition which may have become infected. Apply such a cream as directed by your medical professional but usually twice a day for one to two weeks. After this, they must maintain their clean and dry regime and apply an emollient ointment (not cream) to moisturize the skin. This should be applied after each bowel movement and at night. Continue until no longer needed. At any time, persons may use antihistamine treatments orally, to control the itching.
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