Flexural psoriasis is one of several clinical variants of psoriasis. As the name suggests, it affects the flexural sites; these typically include the skin folds on the axillae, groins, submammary skin, natal cleft, face and the genitalia. Flexural psoriasis may be the sole manifestation of psoriasis or may be part of more widespread psoriasis including extensor sites.
Flexural psoriasis in natal cleft with typical psoriasis on buttocks.
Photograph: Dr Anshoo Sahota
There is a need to differentiate flexural psoriasis from other forms because treatment may need to be modified to take into account the more delicate skin on flexural sites. In addition, flexural psoriasis may in part be caused by the effects of yeast infections and therefore appropriate treatment is important.
Occasionally flexural psoriasis can be a diagnostic challenge, particularly in the early stages of the disease. The humid environment of flexural sites can lead to psoriatic plaques, which are erythematous and shiny rather than the raised red scaly plaques of typical psoriasis.
|A 34-year-old man was referred by his GP with a recent onset rash on his axillae. He initially suspected it was an allergy to his deodorant and changed to a ‘sensitive skin’ brand without any improvement. The rash was slightly itchy and partially responded to hydrocortisone 1% cream. He was otherwise well and had no family history of skin disease, but did admit to a past history of ‘dandruff’.|
Examination of the axillae revealed bilateral symmetrical erythema without scaling or pustules. Further examination revealed similar erythema in the groins and natal cleft. A diagnosis of mild flexural psoriasis was made.
Treatment was started with a daily emollients and Trimovate cream (clobetasone butyrate, nystatin, oxytetracycline) with instructions to apply it each night to affected skin for two weeks and then when required thereafter. The patient was warned to expect the cream to have a yellowish colour and to wash off the cream each morning.
Within one week there was some improvement and by two weeks the flexural psoriasis had improved significantly and was no longer itchy. The reassurance about the nature of the condition and the safety of the treatment also reduced the patient’s anxiety and allowed him to continue using his treatment intermittently in the long term.
Patients with a new diagnosis of psoriasis need a discussion tailored to their needs. Some will have a family history and will be familiar with the condition but most will need reassurance that psoriasis is not contagious or malignant and is treatable even though it cannot be cured.
It is helpful to give realistic goals for treatment at an early stage so that patients realise that the aim of treatment is to help them live a near normal life rather than struggling to achieve complete remission of the disease.
Topical treatment options
Most patients will improve with simple emollients and low potency topical steroids. The choice of emollient is very dependent on the patient’s preferences and factors such as the ease of application, the feel and smell of the product and its cost are all important.
If emollients alone are not enough, topical steroids can be used, although care must be taken to avoid atrophy at flexural sites. Typically, hydrocortisone 1% (mild) or clobetasone (medium) are suitable topical steroids that can be used daily to achieve remission and then used intermittently to control flares.
Combinations of topical steroid with anti-yeast agents are sometimes more effective than topical steroids alone particularly on areas prone to intertrigo or on facial disease. Typical products in the UK include Canesten HC cream, Daktacort Hydrocortisone cream and Trimovate cream.
Coal tar products with or without mild steroid can be useful if the flexural psoriasis is itchy. Examples of these include Alphosyl HC cream and Exorex lotion. Most cases of flexural psoriasis, however, are not particularly itchy.
If mild or moderate potency topical steroids are insufficient, a short course of a potent topical steroid (with or without anti-yeast agents eg betamethasone or betamethasone with clotrimazole cream) may be used cautiously. Alternatively, topical calcineurin inhibitors such as tacrolimus ointment 0.03% or 0.1% can be helpful, particularly on facial sites (although this is an unlicensed indication).
Vitamin D analogues (alone or in combination with topical steroid) can be used on flexural sites, however there is a risk of causing local irritation. If patients tolerate these agents they can be used intermittently long term if required. Most other topical agents, including dithranol products and topical retinoids, are too irritant to use on flexural sites and are therefore best avoided.
Systemic treatment options
Most cases of flexural psoriasis will improve with topical treatment, but where this is ineffective, systemic treatment should be considered. These include the systemic treatments for typical psoriasis such as methotrexate, ciclosporin and vitamin A analogues as well as the biological agents including etanercept. In addition, some patients benefit from oral anti-yeast agents such as itraconazole taken for one to two weeks.
Burns T, Griffiths C, Breathnach S, Cox N (eds). Rook’s Textbook of Dermatology 7th ed. Oxford: Blackwell Publishing Ltd, 2004.
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