Anal eczema contact allergicL23.8

• Acute, subacute or chronic dermatitis of the anoderma, anal and perianal skin, caused by a contact allergy
• Frequently associated with hemorrhoidal disease, intestinal candidiasis, poor anal hygiene, parasitosis, obesity and hyperhidrosis, anatomical malformations, e.g. funnel anus.
• The resulting "symptom of the wet and itchy anus" leads to macerative dermatitis associated with burning and torturous notorious pruritus, which in turn promotes contact allergy.

About 40% of all anal eczema is caused by contact allergies. In a larger overview, the allocation diagnosis "anogenital dermatosis" could only be made in about 25% of the cases of allergic contact eczema. Chronic irritative anal dermatitis was diagnosed in about 12%. It is not uncommon for a banal intertrigo or candidosis to be present (Kügler 2005).

Mainly caused by the use of skin care products, intimate sprays, toilet paper and proctologicals, especially during long-term use.

The main allergens detected are cinchocaine HCl 6.3%, mafenide 2.3%, hexylresorcin 2%, lidocaine HCl 1.4%, albothyl 0.6%, chamomile extract 0.6%, quinine sulphate 0.3% and menthol 0.3%. Increasingly, "toilet paper allergy" is also observed: the allergic potency when using white cellulose paper is very low, but increases significantly when using moist, recycled or dyed toilet paper. Kathon C6 and Euxyl K400 are the most commonly detected.

In contrast, ingredients of detergents seem to play a subordinate role.

In the acute stage, intense erythema of the anal and perianal region, usually sharply limited to the contact area, with punctiform and flat erosions, rhagades, linelike scratch marks as an expression of the usually severe itching.

In the chronic stage with mostly persistent itching, increasing lichenification with coarsening of the radial fold, macerated areas, bizarre rhagadiform and also extensive erosions; in addition scratching effects.

The clinical picture varies depending on the clinical stage (acute, subacute, chronic). No scaling.

• Epicutaneous test according to the guidelines of the German Contact Allergy Group (DKG). Especially testing of preservative additives, fragrances (frequently!), external active ingredients (especially in proctologicals, such as mafenide, hexylresorcinol, lidocaine, albothyl, camomile extract, quinine sulphate, menthol), allergens in ointment bases (e.g.e.g. wool wax alcohol), intimate sprays, toilet papers (Kathon C6, Euxyl K 500), powders, depilators, condoms, lubricants, disinfectants.
• Stool examination for parasites (tesafilm tearing) and yeasts!
• Proctological examination with exclusion of haemorrhoids.
• Exclusion of other diseases leading to the clinical picture of anal eczema (see below: eczema, anal eczema).

Lichen simplex chronicus; atopic eczema; psoriasis inversa; extramammary Paget's disease; Bowen's disease; chronic candidiasis; eczema, anal eczema cumulative-toxic; pemphigus chronicus benignus familiaris; streptococcal dermatitis, perianal.

• If you suspect something, take off all external agents.
• For acute weeping anal eczema: Short-term application of non-irritating (avoidance of ointment bases containing polyglycol, burning on weeping surfaces!) topical glucocorticoids (e.g. 0.1% triamcinolone acetonide in Vaseline); cleaning with olive oil; soap-free anal showers, sitz baths with synthetic tanning agents (e.g. Tannosynt liquid, Tannolact). Potassium permanganate sitz baths with microbial overlay.
• In case of irritant toxic overlay: treatment and removal of the underlying trigger mechanisms. These include: haemorrhoidal disease, diarrhoea, mariscuses, worm disease.
• In the case of chronic anal eczema, fat ointments that are as indifferent as possible, such as Vaselinum alb. Temporary local measures with low-potency glucocorticoids such as hydrocortisone 0.5-1% (e.g. Hydro-Wolff, R120 ) are useful.
• Caution! Patients are often pre-treated with corticosteroids for a long time!
• In the long term, a local therapy with low-sensitizing, anti-inflammatory topicals (e.g. 1-5% ichthyol) in non-irritating bases should be aimed for. Supplementary: Sitting baths with synthetic tanning agents (e.g. Tannosynt liquid, Tannolact), soap-free anal showers. A diet is of general importance: avoidance of spicy foods, avoidance of foods with high fruit acid content.

• Remember! The following applies to the base: the fatter, the better! If possible, be allergologically neutral!

Common triggers of anal eczema

1. Kügler K et al. (2005) Anogenital dermatoses--allergic and irritative causative factors. Analysis of IVDK data and review of the literature. J Dtsch Dermatol Ges 3:979-986.
   
2. Proske S et al. (2004) Anal eczema and its benign simulators. dermatologist 55: 259-264

3. Rajalakshmi R et al (2011) Lichen simplex chronicus of anogenital region: a clinico-etiological study. Indian J Dermatol Venereol Leprol 77:28-36

4. White hair E (2015) Genitoanal pruritus. dermatologist 66:53-59