Introduction

The pattern and form of acute dermatological conditions that present to the emergency department (ED) are confusing in that the clinical features such as vasodilatation, exfoliation, blistering or necrosis are the common endpoint of many different inflammatory processes in the skin. The pathological response involves cytokines or chemokines, and their effects create the visible response(s). The important clinical differences seen in these acute reactions should be recognized by the trained observer (see Tables 15.1.1 and 15.1.2). This chapter aims to provide a clinical pathway from taking an appropriate history to having knowledge of the distinguishing clinical features of the likely differential diagnoses. The emergency presentations discussed are limited to specific dermatological conditions that may be seen in an ED as a true urgency. The presentation of skin infections (Ch. 9.6) and anaphylaxis (Ch. 28.7) are covered elsewhere. It is important to use other resources with this book, such as a dermatology atlas or specialized texts, to provide greater detail on the conditions mentioned.

Table 15.1.1 Definition of macroscopic skin pathological lesions

Table 15.1.2 Definitions of patterns in skin disorders

POTENTIALLY LIFE-THREATENING DERMATOSES

Toxic epidermal necrolysis and Stevens–Johnson syndrome

Toxic epidermal necrolysis (TEN) and Stevens–Johnson syndrome (SJS) are disorders of mucosal ulceration at two or more sites with cutaneous blisters. Confusion exists between these two diagnoses and erythema multiforme (EM), although some consider SJS a severe form of EM major, and TEN a severe form of SJS. This distinction is not important in the emergency setting, but rather it is the recognition of a potentially serious dermatosis that is important.

The difference between TEN and SJS is defined by the extent of skin involvement. TEN affects more than 30% of the body surface area, whereas SJS affects 10% or less (see Fig. 15.1.1). TEN/SJS overlap refers to patients where there is between 10 and 30% body surface area involvement. Again this distinction is academic, as the rash may evolve over hours or days to become true TEN.

Fig. 15.1.1 Toxic epidermal necrolysis.

The key to making the diagnosis is recognizing mucosal involvement, which may include conjunctival, oral mucosal, genital and sometimes perianal erosions, as well as an often severe haemorrhagic cheilitis. Nikolsky sign is positive, that is dislodgement of the epidermis by lateral finger pressure in the vicinity of a lesion causes an erosion, or pressure on a bulla leads to lateral extension of the blister.

TEN is almost always due to drug ingestion, which can include in rare instances illicit drug ingestion. Therefore ask about prescribed and over the counter drugs such as NSAIDs, sulphonamides, and anticonvulsants such as sodium valproate and lamotrigine, as well as illicit drug use.

Investigations

Request a full blood count, urea and electrolytes, liver function tests (LFT), and a blood glucose level. These may also be used to calculate the prognostic SCORTEN (see below). Send blood for HIV testing also, after appropriate counselling, as the risk of developing TEN is increased in patients with HIV and AIDS. If a biopsy is taken, clearly state on the request slip that the differential diagnosis is of toxic epidermal necrolysis. Epidermal (keratinocyte) necrosis is the histological hallmark of this condition.

Management

Cease the triggering drug or agent immediately, and involve the intensive care unit and/or the burns unit. Arrange assessment and treatment by the ophthalmology and ear, nose and throat teams for ocular and oral/pharyngeal involvement, respectively.

TEN may continue to evolve and extend over days, unlike a burn, where the initial insult occurs at a defined time. The SCORTEN severity scoring system for TEN (see Table 15.1.3) is similar in concept to the Ranson’s score for pancreatitis. Calculate the SCORTEN severity score within 24 h of admission and again on day 3 to aid the prediction of possible death (see Table 15.1.4).

Table 15.1.3 SCORTEN severity score for toxic epidermal necrolysis (TEN)

Table 15.1.4 SCORTEN mortality prediction*

* Guegan S, Bastuji-Garin S, Poszepczynska-Guigne E, et al 2006. Performance of the SCORTEN during the first five days of hospitalization to predict the prognosis of epidermal necrolysis. Journal of Investigative Dermatology 126: 272–76.

Erythema multiforme

EM presents with malaise, target lesions, blistering and sometimes pain or pruritus, but with only one mucous membrane involved (EM major) or none (EM minor).

Most cases of EM are due to drug ingestion, Herpes simplex or Mycoplasma infection, although in up to half no cause is identified (see Fig. 15.1.2). It is acceptable to treat erythema multiforme with a systemic steroid such as predinosolone (0.5–1 mg/kg/day).

Fig. 15.1.2 Erythema multiforme.

Sweet’s syndrome may resemble severe EM in the acute oedematous phase, presenting with fever, arthralgia, neutrophilia and sterile, non-infective but painful pustules, plaques or nodules over the head, trunk and arms. It may recur, and can be associated with a haematological malignancy such as myeloid leukaemia, pregnancy or infection such as Yersinia or Streptococcal (see Fig. 15.1.3). Sweet’s syndrome is very responsive to systemic steroids; however, a sinister underlying cause such as leukaemia must be sought for and excluded by appropriate investigations.

Fig. 15.1.3 Sweet syndrome.

Erythroderma

The causes of erythroderma include eczema (40%), psoriasis (22%), drugs (15%), lymphoma (Sezary syndrome) (10%) and idiopathic (8%).

Complications of erythroderma

These include:

Investigations

Send a full blood count (FBC) with film and differential, UE&C, LFTs and blood cultures if the temperature is greater than 38 °C, or if the patient appears unwell with rigors (even if the temperature is normal, as the patient may have become poikilothermic but still be septic). Send skin swabs for microscopy and culture and request a chest X-ray. Arrange biopsy of the skin if the cause of the erythroderma is uncertain.

Management

Treatment is general and supportive, and includes:

Related posts:

18: ENT 12: Metabolic 29: Toxicology 26: Emergency Medical Systems 11: Endocrine 5: Cardiovascular

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