Red legs in the elderly – cellulitis or eczema?

Dermatology GPSI Dr Stephen Hayes stresses the importance of accurate diagnosis when managing red legs in older patients

Very frail elderly patients – as well as having diabetes, heart disease, neurological disease and so on – have their share of skin problems, not least on the lower legs. Foremost among these are the consequences of venous stasis. Clinical overlap and dual pathology may test the doctor's diagnostic skills when differentiating between eczema and infection. Effective management of these patients requires us to differentiate between primary skin disease and the cutaneous results of underlying circulatory disorder.

The pathophysiological principles of venous leg disease,which are essentially hydraulic, are well enough understood – but often apparently forgotten when it comes to understanding and managing the resultant skin problems.

Ordinarily, walking compresses the veins in the leg muscles which pumps the deoxygenated venous blood back towards the heart and lungs. But this process is compromised in the immobile.

Central obesity makes it worse, as intra-abdominal fat increases venous pressure. The consequent chronic venous hypertension in the legs causes oedema, stagnation of blood, lipodermatosclerosis, venous leg ulcers and varicose (venous or stasis) eczema.

Diagnosis

Managing red legs in the elderly depends on diagnosis.

1. Eczema is the most common erythematous rash in all age groups. It takes many forms, some of which are partly age specific. For all kinds of eczema and dermatitis there are the same three management rules:

• remove underlying causes, such as irritants, allergens or oedema, when possible

• make frequent use of suitable emollients to restore and maintain epidermal integrity

• use topical steroids in suitable strength and duration to control inflammation.

2. Varicose eczema will respond to emollients and topical steroids if there is inflammation and will respond to compression if appropriate and if tolerated. If the compression isn't tight enough to be uncomfortable it probably won't work.

Congestive cardiac failure should be treated if present and weight loss will also reduce oedema. For chronic lymphoedema, ankle brachial pressure index should be reassessed before starting compression.

If infection is present, treat with a short course of oral antibiotic. Resistance to topical fucidic acid is widespread and the role of emollients containing antimicrobials is a subject of debate.

3. Asteatotic eczema is caused by elderly skin becoming dry as sebum production drops off with age. We need some sebum to maintain epidermal integrity – lack of it may lead to cracked, dry skin.

The problem is made worse by excessive bathing, since soap and other detergents remove the already depleted cutaneous lipid.

The perfect vicious circle occurs when the primary asteatotic eczema leads to increased bathing. When the rash then worsens, this is attributed to infection and a proprietary disinfectant is added to the bath, causing a primary irritant dermatitis.

On a really bad day, this asteatotic and irritant dermatitis will be misdiagnosed as scabies and a scabicide will be prescribed, which causes further irritation. At this stage, the rash may be very inflamed and require a potent topical steroid.

There is some overlap between asteatotic and varicose eczema. Treatment consists of a topical steroid of appropriate strength to treat the inflammation and then dealing with the underlying dryness and cracking by avoiding things that make it worse (excessive bathing, overheating) and using emollients – the greasier the better.

White soft paraffin/liquid paraffin 50:50 can be helpful in the frail elderly who need emollients applied for them. It is very long lasting and can be applied once daily.

4. Discoid eczema is more common after late middle age and is often misdiagnosed as fungal infection or psoriasis. Lesions are discrete, typically oval or angular in shape (only sometimes ‘coin shaped' as per the text books), very strongly inflamed, often weeping, severely itchy to the point of being painful and often secondarily infected with staphylococcus.

Lesions can appear on the trunk but are most often found on the legs. The patient pictured (below) had been given three courses of antibiotics for presumed cellulitis without benefit. The skin is broken and the lesions are discrete, not confluent, so this is not cellulitis (see below). Very potent topical steroids cleared it up in a week.

5. Cellulitis is a subcutaneous infection, usually streptococcal or staphylococcal, which is typically unilateral, painful, confluent and associated with pyrexia and malaise. Tinea pedis may provide a portal of entry. Scale or vesicles are absent, as the infection is below the dermis.

Cellulitis may be incorrectly diagnosed in red, elderly legs where the primary problem is venous stasis or eczema. Bilateral erythema is unlikely to be caused by cellulitis, especially if the patient is apyrexial.

Infection in eczema is usually secondary, and caused by broken skin and scratching. Antibiotics may be necessary if infection is present but cannot help the underlying hydraulic problem.

Hit hard with steroids, review and reduce

Modern practice for strongly inflamed, steroid-responsive skin disease is to use a potent, or very potent, topical steroid once- or twice-daily for a week or so and then review. If the steroid has worked, then reduce either to a less potent compound or to less frequent application.

This has replaced the old fashioned – and conservative – approach of starting weakly and gradually building up potency. In my experience, more patients suffer from the failure to use a strong enough steroid because of steroid phobia – either theirs or their GP's – than through excessive use. Of course, using steroids too often, too strong and too long can lead to skin thinning and other problems, but topical steroid side-effects need never be a problem unless the doctor puts large tubes on repeat prescription.

Contact dermatitis to a topical application or component of bandaging is a possibility if there is a confluent rash corresponding to dressings. Think about referral for patch testing in such cases. Neomycin, rubber or elastic are likely culprits.

Eczema, whether varicose, asteatotic, discoid or other, is the most common cause of red legs in the elderly and usually responds to appropriate treatment. Cellulitis is usually unilateral, confluent, painful, non-scaly and associated with fever and malaise.

Dr Stephen Hayes is a GPSI in dermatology in Southampton and hospital practitioner in the lesion clinic at Southampton University Hospital Trust. He is a trustee and committee member of the Primary Care Dermatology Society www.pcds.org.uk

Competing interests None declared

The PCDS was formed in 1994 by a group of GP skin specialists who recognised the need for a forum for GPs in the UK and Ireland to exchange views on primary care dermatology, hone skills and develop clinical research.
The society also provides a voice and support forum for GPSIs in dermatology.
Our key objectives are:
• To provide an innovative forum for GPs and GPSIs with
a common interest in dermatology to exchange views and
ideas, encourage research, improve patient management and promote education both for the GP and the healthcare team.
• To encourage an interest in and provide an arena to promote and establish a clearer understanding of dermatology in primary care.
• To create wider awareness and appreciation of the benefits of shared care and to encourage strong links with specialist groups such as the British Association of Dermatologists (BAD)
The Society holds a series of educational meetings around the country from dermoscopy to surgical training to general dermatological subjects, all delivered by both GPs and consultant dermatologists