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You may not know about anogenitalskin disorders

Consultant dermatologist Dr Sallie Neill gives tips on diagnosis and management

Consultant dermatologist Dr Sallie Neill gives tips on diagnosis and management

1. Examine the skin at other flexural sites on the body – to help give a clue to the diagnosis

The four most common, non-neoplastic, non-infective dermatoses that affect the anogenital skin are irritant contact eczema, psoriasis, lichen sclerosus and lichen planus. The typical morphology of a dermatitis is altered at flexural sites so a full examination of the skin is often essential to help confirm the diagnosis.

This is particularly true of psoriasis where the typical silvery scaly rash is replaced by beefy red erythema. Examination of other flexural sites such as the axillae, behind the ears and under the breasts may help and an examination of the mouth, nails and scalp may give extra clues.

Topical treatment for most of the anogenital skin diseases involves a soap substitute, topical steroid and barrier ointments. The steroid potency will depend on the condition and the severity. Safe practice would be the use of the steroid ointment once a day and 30g should last three months initially and six months to a year for maintenance therapy.

2. Determining whether the skin, mucosa or both are involved can help with differential diagnosis

The anogenital area is a mucocutaneous junction and this can help in diagnosis. If the rash involves both skin and a mucosa it will usually be lichen planus or one of the auto-immune blistering disorders. Examine other mucosal sites, particularly the mouth. Lichen sclerosus and psoriasis do not normally involve mucosae.

3. Scarring is an important clinical sign and can help both with diagnosis and assessing response to treatment

It is important to note any scarring. This again narrows the differential diagnosis and helps in monitoring response to treatment. The main features to note in women are whether the clitoral hood is sealing over the clitoris, the labia minora are present, altered or lost and narrowing of the introitus. If there is involvement of the vulval vestibule, which is a mucosa, it is important to examine the vagina to assess its patency.

In men it is important to examine the prepuce to assess any phimosis, the coronal sulcus which may be tethered and around the urethral opening.The scarring dermatoses include lichen sclerosus, lichen planus, mucous membrane pemphigoid and pemphigus.

4. Candida may be present secondary to the underlying dermatosis, which must be identified and treated

If a skin swab is positive for candida it does not mean the patient has candidiasis as the primary diagnosis. It must be remembered that candidal carriage in the gut is not uncommon in healthy individuals. If the skin is affected by a dermatitis its integrity is altered and the candida can overgrow as a secondary event.

This is often the reason the patient does not respond to anti-candidal treatment. The underlying dermatosis needs to be treated.

5. Think of non-compliance, urinary incontinence and the possibility of a complication if the patient is not improving

Non-compliance is the most common reason for patients failing to respond to treatment. Package inserts for the topical steroids warn the patient that the treatment should not be used on the anogenital skin or, if it is, it should only be used for a few days.

It is important to let the patient know about this warning but reassure them that it is safe to use as you have advised. It is also important to advise the patient that the aim is not to 'cure' but to 'control' the condition.Most of the skin diseases will run a course of flares and remissions and the patients will have to use their treatments as and when required.

Ask yourself, is there an additional diagnosis? Has the patient a problem with urinary incontinence that is exacerbating the skin condition? The addition of a barrier ointment will help.

Has a complication developed on the background of lichen sclerosus or lichen planus? For example, a squamous cell carcinoma or area of intra- epithelial neoplasia.

Finally it is essential to remember that a genital skin problem will have a serious impact on sexual function. It is important that the patient is given the opportunity to discuss this and given the appropriate help if necessary.

Sallie Neill is a consultant dermatologist at St John's Institute of Dermatology, St Thomas' Hospital, Chelsea and Westminster Hospital and St Peter's Hospital, Chertsey, Surrey

Competing interests None declared

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