Ridley's The Vulva. Группа авторов
explanation on the safe use of topical steroids for vulval disease needs to be given to the patient. Topical steroids are safe to use in pregnancy, and a systematic review shows no link of exposure to topical steroids and pregnancy outcome [7]. There was a possible link of low birth weight with the use of large quantities of topical steroids, but this would not be relevant for the small amounts used to treat the vulva.
Table 8.1 UK classification of topical steroids.
| Class | Potency | Examples |
|---|---|---|
| I | Mild | 1% hydrocortisone |
| II | Moderate | Clobetasol butyrate 0.05% Fludroxycortide |
| III | Potent | Betametasone valerate 0.1% Betamethasone dipropionate 0.05% Mometasone furoate 0.1% |
| IV | Superpotent | Clobetasol propionate 0.05% Diflucortolone valerate 0.3% |
Table 8.2 US classification of topical steroids.
| Class | Potency | Examples |
|---|---|---|
| I | Superpotent | Clobetasol propionate 0.05% Betamethasone dipropionate 0.05% |
| II | Potent | Mometasone furoate 0.1% |
| III | Upper mid‐strength | Betamethasone valerate 0.1% |
| IV | Mid‐strength | Fluocinolone acetonide 0.03% |
| V | Lower mid‐strength | Fluticasone propionate |
| VI | Mild | Fluocinolone acetonide 0.01% |
| VII | Least potent | 1% hydrocortisone |
The vulva is an area that is naturally occluded and therefore the penetration of the steroid is enhanced. It has been shown that there is a ‘reservoir effect’ in flexural areas in which the steroid can stay in the stratum corneum for up to two weeks. The topical steroid therefore needs to be applied only once daily [8]. When deciding about the correct amount to prescribe, a useful measure is the fingertip unit [9]. This is the amount squeezed from a standard tube that covers the distance between the distal interphalangeal joint and the tip of the index finger and equates to approximately 0.5 g (Figure 8.2). About half of this, or a pea‐sized amount, is adequate for one application to the vulva. In general, tapering regimens are used so that the frequency of application is reduced over time. This helps to prevent tachyphylaxis, where there is loss of effect with continuous treatment.
Intralesional injection of steroid can be helpful in hyperkeratotic lesions such as hypertrophic lichen planus or nodular prurigo. Foam preparations, such as those used in inflammatory bowel disease, are helpful for intra‐vaginal use. Other options include prednisolone pessaries or a small dilator coated with a topical steroid ointment in conditions such as erosive lichen planus.
Figure 8.2 Fingertip unit.
Adverse effects
Most side effects are due to inappropriate use, either in duration of treatment, excessive amounts applied, or from the incorrect potency of preparation for the condition. The potential side effects are local at the site of application or very rarely from systemic absorption [10]. These effects are more of a risk in children where the ratio of the body surface area to body weight is higher.
Local effects
Local effects are atrophy and striae due to reduced synthesis of collagen, telangiectasia, and purpura (Figure 8.3). The telangiectasia are due to dilatation of the capillary vessels. Some of the change may be reversible if the treatment responsible is stopped.
A papular, erythematous eruption is sometimes seen on the thighs, buttocks, and inguinal folds. This has many features in common with peri‐oral dermatitis – a rosacea‐like condition seen on the peri‐oral skin of young females who have been applying topical steroids. The treatment is to withdraw the topical steroid slowly, and oral tetracyclines may be needed at the same time.
If a fungal infection is mistaken for an eczematous process and a topical steroid applied, the scaling is lost and is replaced by papules and nodules without the usual features of tinea cruris. This picture is then termed tinea incognito (see Chapter 19) and may require systemic antifungals for treatment.
Reactivation of viral infection such as human papillomavirus (HPV) and herpes simplex can occur. This can often respond to a reduction in potency of the steroid, and in the case of herpes simplex, a prophylactic dose of aciclovir (200–400 mg twice daily) can be given if intensive potent steroid treatment is needed as in the induction regimen for lichen sclerosus.Figure 8.3 Steroid telangiectasia and atrophy in a patient using excessive quantities of topical steroid.
Contact allergy can occur to the steroid molecule itself. This is more common with the non‐fluorinated preparation [11].
Prolonged use of a topical steroid with occlusive nappies has been implicated in infantile gluteal granuloma.
Systemic effects
Suppression of the hypothalamic–pituitary–adrenal (HPA) axis leading to iatrogenic Cushing’s syndrome can occur if large amounts of a potent steroid are used on large areas continuously, but this systemic effect is exceptionally rare with the amounts used on the vulva. Reports of Cushing’s syndrome have been described in children, but in all cases there was excessive, unsupervised use [12,13], with one case using 60g of an ultra‐potent steroid in 8 weeks, far in excess of recommended amounts. Cushing’s can present with central obesity, a buffalo hump, purpura and striae, proximal muscle weakness, osteoporosis, hyperglycaemia, and sometimes psychiatric disturbance. Investigation with a synacthen test will confirm the diagnosis, and referral for endocrinological advice on management is needed.
Calcineurin inhibitors
The topical calcineurin inhibitors (CNIs) have anti‐inflammatory and immunomodulatory actions. They inhibit calcineurin phosphatase, resulting in the reduction in T‐cell activation and cytokine production. They have been