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Emergency dermatology


Essentials

  • 1

    Emergency dermatology presentations may be divided into potentially life-threatening dermatoses, vesiculo-bullous conditions, petechial and purpuric rashes, and inflammatory dermatoses such as eczema, urticaria and psoriasis.

  • 2

    Potentially life-threatening presentations include Stevens-Johnson syndrome, toxic epidermal necrolysis (TEN), Sweet syndrome, drug rash with eosinophilia and systemic symptoms (DRESS) and erythroderma.

  • 3

    Petechial or purpuric rashes may represent cutaneous or systemic vasculitis, or coagulopathy; investigations are targeted at internal organ involvement, and management is multidisciplinary.

  • 4

    Cutaneous infections may be a primary presentation or a secondary complication of a primary dermatosis.

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 process 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 ( 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.

Table 15.1.1
Definition of macroscopic skin pathological lesions
(Modified with permission from Rook AJ, Burton JL, Champion RH, Ebling FJG. Diagnosis of skin disease. In: Bolognia J, Jorizzo J, Rapini R, eds. Textbook of Dermatology . Oxford: Blackwell Scientific; 1992.)
Papule Circumscribed firm raised elevation, less than 0.5 cm in diameter
Nodule A solid or firm mass more than 0.5 cm in the skin, which can be observed as an elevation or can be palpated
Purpura Red-purple discoloration of skin or mucous membranes due to extravasation of red blood cells
Pustule An accumulation of yellow-white fluid within a vesicle or papule; may be centred around a pore, such as a hair follicle or sweat glands, and sometimes appears in normal skin, including the palms and soles
Vesicle (s) A visible accumulation of fluid in a papule of <5 mm
The fluid is clear, serous-like and is located within or beneath the epidermis
Bulla (ae) Large fluid-containing lesion of >5 mm
Plaque An area or sheet of skin elevated and with a distinct edge, of any shape and usually wider than 1 cm

Table 15.1.2
Definitions of patterns in skin disorders
Annular Ring-like or part of a circle
Linear Line-like
Arcuate Arch-like
Grouped Local collection of similar lesions
Unilateral One side
Symmetrical Both sides

It is important to use other resources with this chapter, such as a dermatology atlas or specialized texts, to provide greater detail on the conditions mentioned. The presentation of skin and soft-tissue infections ( Chapter 9.5 ) and anaphylaxis ( Chapter 2.8 ) are covered elsewhere.

Potentially Life-Threatening Dermatoses

Stevens-Johnson syndrome and toxic epidermal necrolysis

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are acute severe cutaneous presentations characterized by extensive necrosis and detachment of the epidermis. Confusion exists between these two diagnoses and erythema multiforme (EM). EM was previously considered a variant of SJS/TEN, but it is now commonly accepted that they are clinically distinct disorders with different aetiologies and prognosis. Most consider EM minor and major to be related to infections (e.g. herpes simplex virus [HSV]); whereas SJS/TEN are variants of the same disorder defined by severity and are usually caused by drugs. SJS is also known to be triggered by mycoplasma infections. The distinction between EM major, SJS and early TEN is not important in the emergency setting; rather it is the recognition of a potentially serious dermatosis that is important, and the need for comprehensive assessment and monitoring.

The difference between SJS and TEN is defined by the extent of skin involvement. SJS affects 10% or less of the total body surface area (TBSA), whereas TEN affects more than 30% TBSA ( Fig. 15.1.1 ). ‘TEN/SJS overlap’ refers to patients where there is between 10% and 30% TBSA involvement. The extent of necrolysis must be carefully evaluated since it is a major prognostic factor. Patients with HIV, over age 65 and those with malignancy are at increased risk of TEN.

Fig. 15.1.1, Toxic epidermal necrolysis.

Clinical features

Clinical features of SJS/TEN include a prodrome with upper respiratory tract (URTI)-like symptoms, fever, malaise, vomiting and diarrhoea. Skin pain may herald the development of SJS/TEN and is a sensitive sign of impending epidermal detachment. Symmetrical erythematous macules, mainly localized on the trunk and proximal limbs, evolve progressively to dusky erythema and confluent flaccid blisters leading to epidermal detachment.

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. Gastrointestinal and respiratory mucosa can also be involved. ‘Nikolsky sign’ is the dislodgement of the epidermis by lateral finger pressure causing an erosion or lateral extension of the blister. It is a key finding in TEN.

TEN is almost always due to a drug which may, in rare instances, include illicit drug ingestion. Therefore ask about prescribed and over-the-counter drugs, such as non-steroidal anti-inflammatory drugs (NSAIDs), sulphonamides, allopurinol, nevirapine and anticonvulsants, such as sodium valproate and lamotrigine, as well as illicit drug use.

Investigations

Request a full blood examination (FBE), urea and electrolytes (U&E), liver function tests (LFT) and a blood glucose. These may also be used to calculate the prognostic SCORTEN (see below). Other tests to consider include antinuclear antibody (ANA), extractable nuclear antigens (ENA), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), anti-skin antibodies, HIV and mycoplasma serology. Skin swabs for viral polymerase chain reaction (PCR) and bacterial culture should be taken, and chest x-ray (CXR), urine and blood cultures as indicated.

Biopsies are taken from the edge of a blister for histology and a perilesional site for direct immunofluorescence. Clearly state on the request slip that the differential diagnosis is of TEN. 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 early. Rapid institution of resuscitation measures is associated with a more favourable prognosis. Arrange assessment and treatment by the ophthalmology and ear, nose and throat teams for ocular and oral/pharyngeal involvement, respectively; urological and/or gynaecological review of patients with TEN is essential to prevent genito-urinary scarring.

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 ( Box 15.1.1 ) is similar in concept to the Ranson’s score for pancreatitis. Calculate the SCORTEN severity score within 24 hours of admission and again on day 3 to aid the prediction of possible death ( Table 15.1.3 ).

Box 15.1.1
SCORTEN severity score for toxic epidermal necrolysis

  • Age >40 years

  • Heart rate >120/min

  • Presence of cancer or haematological malignancy

  • Epidermal detachment involving body surface area >10% on day 1

  • Blood urea nitrogen >10 mmol/L (28 mg/dL)

  • Glucose >14 mmol/L (252 mg/dL)

  • Bicarbonate <20 mEq/L

(One point is given for each variable)

Table 15.1.3
SCORTEN mortality prediction
Score Mortality (%)
0–1 3.2
2 12.1
3 35.3
4 58.3
5 or greater 90.0
(Reproduced with permission from Guégan S, Bastuji-Garin S, Poszepczynska-Guigné E, et al. Performance of the SCORTEN during the first five days of hospitalization to predict the prognosis of epidermal necrolysis. J Invest Dermatol . 2006;126:272–276.)

Erythema multiforme

While not life threatening, EM is part of the differential of a potentially life-threatening reaction, such as SJS/TEN. EM is an acute usually mild, self-limited cutaneous and/or mucocutaneous syndrome that presents with the rapid onset of lesions within a few days, favouring acral sites. These are often mildly pruritic or painful papular or urticarial lesions, as well as the classical ‘target’ lesions, but with only one mucous membrane involved (EM major) or none (EM minor). Typically, the oral mucosa is involved showing a few, discrete, mildly symptomatic erosions. Rarely, the eye, nasal, urethral or anal mucosa may be involved. A mild prodrome may precede development of the rash.

Most cases of EM are due to infection, most commonly HSV or mycoplasma. Drugs are now considered to be an uncommon cause ( Fig. 15.1.2 ).

Fig. 15.1.2, Erythema multiforme.

Investigations

Send a baseline FBE, U&E, LFT and CRP, as well as a skin biopsy if the diagnosis is uncertain, swabs for HSV PCR. Request a CXR and mycoplasma serology if there are respiratory symptoms.

Management

Usually, only symptomatic treatment is required with topical steroids, antihistamines, antiseptic mouthwashes and local anaesthetic preparations for oral involvement. For severe cases, treat EM with a systemic steroid, such as prednisolone (0.5 to 1 mg/kg/day). In recurrent EM due to HSV, oral antivirals are effective at preventing relapse.

Sweet syndrome

Sweet syndrome (acute febrile neutrophilic dermatosis) may resemble severe EM in the acute oedematous phase, presenting variably with fevers, arthralgias, sterile potentially painful pustules, plaques or nodules over the head, trunk and arms. The red-purple plaques/nodules are often referred to as ‘juicy’ indicating they are soft and pus-filled though not truly fluctuant.

Sweet syndrome is often a relapsing-remitting presentation that may be associated with an underlying haematological malignancy inflammatory bowel disease, rheumatoid arthritis or other connective tissue disease, pregnancy or infection, such as Streptococcus or Yersinia ( Fig. 15.1.3 ).

Fig. 15.1.3, Sweet syndrome.

Sweet syndrome is highly responsive to systemic steroids; however, any underlying association must be sought and excluded by appropriate investigations.

Drug rash with eosinophilia

Drug rash with eosinophilia and systemic symptom (DRESS) is a severe skin reaction to a drug with systemic manifestations that carries significant morbidity and a mortality rate of 10%. It typically occurs within 2 to 6 weeks of drug initiation. It has been reported with the antiepileptics (phenytoin, carbamazepine, phenobarbital), lamotrigine, sulphonamides (including sulphamethoxazole and trimethoprim combinations and dapsone), minocycline, allopurinol, terbinafine, abacavir and nevirapine. Up to 70% cross-reactivity occurs between different aromatic anticonvulsants, which should therefore be avoided if someone has previously had a major reaction to an aromatic antiepileptic.

Fever and rash are the most common symptoms . Cutaneous involvement is often polymorphic usually starting as a morbiliform rash, which may later become oedematous, exfoliative or erythrodermic, and/or include non-follicular pustules. Often, rash involving the face indicates a more serious drug reaction and facial oedema and lymphadenopathy are frequent hallmarks of this syndrome.

Prominent eosinophilia is a characteristic feature that occurs in 60% to 70% of cases. Potentially serious internal organ involvement, such as hepatitis, nephritis, pneumonitis, myocarditis, thyroiditis and encephalitis can occur. Fever, skin rash and organ involvement may fluctuate and persist for weeks or months after drug withdrawal, with the delayed onset of sequelae reported.

Investigations

Diagnosis can be difficult because of the polymorphic rash and variable organ involvement. A skin biopsy should be taken for histopathology and, although not diagnostic, histological features of a drug reaction will assist in making the diagnosis. Also request a baseline FBE, U&E and LFT. Immunoglobulins and viral serology (Epstein–Barr virus, cytomegalovirus, human herpesvirus 6 or 7 [HHV6, HHV7]) should be sent, as transient hypogammaglobulinaemia and viral reactivation may be associated with fluctuations in symptoms. Other investigations should be as directed for systemic involvement, including baseline CXR, electrocardiogram (ECG) and Thyroid Stimulating Hormone (TSH).

Management

This usually includes admission to hospital and ceasing the suspected drug. Corticosteroids are the first line of therapy despite no consensus on dose or regimen; a starting dose of 0.5 mg to 1 mg/kg/day is reasonable. Fluctuation in symptoms and relapse can occur when the dosage is tapered. As a result, steroid therapy sometimes has to be maintained for several weeks, even months and a steroid-sparing agent may be required. Topical steroids should always be implemented to assist in systemic steroid tapering. Intravenous immunoglobulin (IVIG) may be required in cases of DRESS with severe systemic involvement such as severe hepatitis.

Erythroderma

The causes of erythroderma include eczema (40%), psoriasis (22%), drugs (15%), lymphoma (Sezary syndrome) (10%) and idiopathic (8%). Seek a history of previous skin disease, recent medications or recent changes to skin management, assess hydration and cardiac status, check for oedema, respiratory infection and a deep vein thrombosis (DVT).

Complications of erythroderma

Include:

  • high output cardiac failure

  • transepidermal water loss causing intravascular hypovolaemia (dehydration)

  • hypoalbuminaemia contributing to intravascular dehydration.

  • electrolyte imbalance

  • hypothermia/temperature dysregulation

  • thrombophlebitis/DVT

  • infection, both cutaneous and respiratory, with pneumonia a major cause of death

Investigations

Request an FBE, U&E, LFTs and blood cultures if the patient’s temperature is >38°C, or if the patient appears unwell with rigors, even if the temperature is normal, as the patient may have become poikilothermic but is still septic.

Send skin swabs for Microscopy/Culture/ Sensitivities (MCS) and request a CXR. Arrange biopsy of the skin if the cause of the erythroderma is uncertain.

Management

Arrange to admit the patient. Treatment is general and supportive and includes:

  • attention to temperature control, avoiding hypothermia

  • Intravenous fluid replacement with careful charting of the fluid balance, monitoring urine output in particular

  • referral to dietitian for high protein diet in the first 24 hours

  • DVT prophylaxis.

Specific treatment includes:

  • bath oil daily in bath or shower

  • wet wraps three times a day (TDS):

    • a.

      topical corticosteroid (as appropriate) applied liberally

    • b.

      50% white soft paraffin, 50% liquid paraffin applied liberally

    • c.

      wet tubular bandage or full-length pyjamas

    • d.

      dry tubular bandage or full-length pyjamas

  • antibiotics for proven infection.

Supervision should be under the direction of the dermatology team. Intensive care may be necessary.

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