Viewpoint : managing dermatological emergencies

GPs rarely see a dermatological emergency, but should be aware of them. By Dr Alvin Lee and Dr Anshoo Sahota

ABSTRACT

Skin problems are common in primary care, but are rarely considered emergencies. GPs need to be aware of them, to avoid missing a serious condition requiring urgent attention. Such emergencies include primary skin conditions with potentially serious outcomes and severe systemic illnesses whose early stages feature skin lesions. Frequent causes include infections, drug reactions and inflammatory disease.

Key words
Anaphylaxis, erythroderma, cellulitis, eczema herpeticum, erysipelas, meningococcus septicaemia, necrotising fasciitis, Stevens-Johnson syndrome, toxic epidermal necrolysis

Cellulitis
Erysipelas and cellulitis are bacterial infection of the superficial dermis and deep dermis respectively, although the term cellulitis is sometimes used for both.1 Erysipelas is often reserved for cellulitis affecting the face. The most common infective agents are Streptococcus pyogenes and/or Staphylococcus aureus and the most common site is the lower limbs. Infection often enters the dermis through broken skin, such as toe web spaces affected by tinea pedis.

Diagnosis is usually clinical, with an ill-defined erythematous patch of skin that is tender and hot to touch and will occasionally have blisters. Often, patients have systemic symptoms, such as malaise and fever. Typically, erysipelas and cellulitis are unilateral; bilateral cases do occur, but a diagnosis of acute lipodermatosclerosis (which is usually bilateral) should also be considered in such circumstances.

Simple cellulitis without systemic symptoms can be managed in the community with oral antibiotics. More complex cellulitis with systemic upset or other comorbidity, such as peripheral vascular disease, chronic venous disease, diabetes or morbid obesity, may require IV antibiotics in secondary care.

Eczema herpeticum
Eczema herpeticum (formerly known as Kaposi's varicelliform eruption) is eczema secondarily infected by herpes simplex virus.2 Facial involvement in uncontrolled eczema, particularly around the eyes, is the most common presentation, although it can affect any dermatitic area and can also affect atopic patients in the absence of active dermatitis. The history is often of an apparent sudden deterioration in the patient's eczema and typical lesions are clustered monomorphic superficial erosions, which may be secondarily impetiginised.

Rarely, the condition can disseminate to other sites, leading to keratoconjunctivitis, encephalitis, hepatitis or even death. Acute management includes treatment of the herpetic infection and the eczema; in addition, any bacterial secondary infection should also be treated. In severe cases, hospital admission for IV antiviral and antibiotics may be needed, but in milder cases, oral therapy in the community may be appropriate. Treatment for the eczema should include emollients and topical steroids.

Meningococcal septicaemia
Neisseria meningitidis, a Gram-negative diplococcus, is present in some healthy nasopharyngeal carriers. It may also be acquired from an infected contact via the nasopharyngeal route. The infection disseminates and penetrates vascular epithelial cells, causing vasculitis and leading to disseminated intravascular coagulation.

Patients can present with respiratory symptoms and systemic upset. Skin signs include purpura, most commonly on the lower extremities and trunk, and haemorrhagic lesions. Individual lesions can coalesce and give a stellate appearance.

If the diagnosis is suspected clinically, the patient should be treated immediately because deterioration leading to death can occur rapidly. Ideally, blood cultures should be taken before giving antibiotics, but should not delay the start of treatment because the mortality of meningitis when present with purpuric skin lesions is more than 40 per cent.

Once an index case has been diagnosed, the consultant in community disease control should be contacted for advice on contact tracing and prophylactic antibiotics for close contacts.

Necrotising fasciitis
Necrotising fasciitis, a rapidly progressive skin infection, can deteriorate to a fatal condition within hours.3 The usual causative agents are group A streptococci and Staph aureus, which are usually introduced into the skin in accidental trauma or postoperatively. It is more common in the immunocompromised, for example, patients with diabetes, those on immunosuppressive drugs, alcoholics and patients with malignancy.

The initial lesion starts as a localised, painful erythematous swelling that progresses over a matter of hours to become cyanotic, blistered and necrotic, with deep gangrene. Patients typically present with systemic involvement, including high fever, tachycardia, hypotension and septic shock.

Management of necrotising fasciitis, which should be carried out in secondary care, involves IV antibiotics, fluid resuscitation and aggressive surgical debridement if the infection is progressing.

Toxic epidermal necrolysis
Toxic epidermal necrolysis (TEN) is a severe, life-threatening condition, in which there is widespread death of the epidermis (necrolysis) as a result of apoptosis induced by a toxin, usually a drug.4 Typically, patients are systemically unwell, with a fever and dusky changes to the epidermis, which peels off with minimal trauma (Nikolsky sign).

True blisters are unusual in TEN because there is very little true inflammation in this condition. There is usually (but not always) a history of recent drug initiation; anticonvulsants and antibiotics are typical causes.

The effect of TEN is similar to that of widespread superficial burns and risks to the patient are similar, including problems with fluid balance, temperature regulation and infection.

Suspected TEN requires immediate admission to secondary care, preferably to a high-dependency unit for administration of IV immunoglobulin (to neutralise the toxin) and supportive management with a multidisciplinary approach. Scarring of the eyes, oral and anogenital mucosa can be serious sequelae in those who survive TEN.

Stevens-Johnson syndrome

Stevens-Johnson syndrome (SJS) is the severe manifestation of erythema multiforme, in which there is mucosal and widespread skin involvement (above). Simple erythema multiforme can be caused by infections and drugs, but SJS is more usually drug-related and in severe cases, may evolve into a disease that is indistinguishable from TEN. More commonly, the clinical and histological features of TEN and erythema multiforme are distinctive enough to make an accurate diagnosis.

Typically, SJS presents with target lesions which have a central necrotic area and a rim of erythema (representing the inflammatory edge), often forming a tense blister. It always requires hospital admission and assessment by a dermatologist. Management of SJS is similar to that of TEN, although it has a better prognosis. Withdrawal of the offending drug, treatment of any causative infection and steroids may be required.

Anaphylaxis
Anaphylaxis is a severe inappropriate response to triggers, such as arthropod bites, drugs and foods. Cutaneous manifestations include pruritus, erythema, urticaria and angioedema.5

Low-grade anaphylaxis can be treated with oral antihistamines, but the danger is of progression to anaphylactic shock, in which bronchospasm and hypotension can lead to collapse and death.

Warning signs include wheeze, tachycardia, nausea and vomiting, indicating a need for subcutaneous adrenaline and transfer to A&E. Patients with anaphylaxis may need to carry an adrenaline pen in case of future exposure to the trigger.

Erythroderma
The definition of erythroderma is the presence of erythema affecting at least 90 per cent of the skin.6 It is a clinical sign, not a diagnosis, and causes include dermatitis (atopic, contact and seborrhoeic types), psoriasis, drug eruptions and cutaneous T-cell lymphoma. A quarter of erythroderma cases may have no identifiable cause.

In erythrodermic psoriasis, there may be an additional feature of pustulation. This is due to severe inflammation causing collections of neutrophils in the epidermis and manifesting as multiple small pustules over large areas of erythrodermic skin. These pustules are sterile because they are not caused by organisms, although a similar appearance can occur in viral exanthems, particularly in children.

Erythroderma causes heat loss and haemodynamic disturbance, with a risk of hypothermia and high output cardiac failure, particularly in the elderly and those with a history of cardiopulmonary disease. Urgent secondary care referral is indicated if these features are present.

Management includes identification and treatment of any underlying cause, bed rest, bland emollients and attention to fluid and temperature needs in a multidisciplinary approach. Erythrodermic pustular psoriasis is one of the few indications for systemic steroids in psoriasis, but care is required because withdrawal of systemic steroids is a trigger for erythrodermic pustular psoriasis.

Conclusion
Dermatological emergencies are uncommon but important because they can have fatal outcomes. An awareness of these conditions will help to identify patients requiring urgent attention in secondary care.

- Dr Alvin Lee is a teaching fellow in dermatology at the Royal London Hospital; Dr Anshoo Sahota is consultant dermatologist at Whipp's Cross University Hospital, London.

Competing interests: None declared

References
1. Du Vivier A. Atlas of Clinical Dermatology (third edition). Churchill Livingstone, Oxford, 2002.
2. Longmore M, Wilkinson IB, Rajagopalan S. Oxford Handbook of Clinical Medicine (sixth edition). Oxford University Press, Oxford, 2006.
3. Seal DV, Hay RJ, Middleton KR. Skin and Wound Infection, Investigation and Treatment in Practice. Martin Dunitz, London, 2000.
4. Sterry W, Paus R, Burgdorf W. Toxic epidermal necrolysis (TEN). In: Thieme Clinical Companions, Dermatology (fifth edition). Thieme, Germany, 2005.
5. Sterry W, Paus R, Burgdorf W. Anaphylactic shock. In: Thieme Clinical Companions, Dermatology (fifth edition). Thieme, Germany, 2005.
6. Burns T, Breathnach S, Cox N et al (editors). In: Rook's Textbook of Dermatology (seventh edition). Blackwell Publishing, Oxford, 2004.

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