Dermatological emergencies

Meet the patient

A 34-year-old woman is two weeks into a course of carbamazepine when she arrives febrile, with painful skin, a crusted bloody mouth, and sheets of epidermis sliding off her back at the lightest touch. The Nikolsky sign is positive and the conjunctivae are weeping.[10]

Two questions now decide whether she lives without blindness: what is this? and what do I do in the next fifteen minutes? Everything below exists to answer those two questions before the biopsy comes back. This is TEN until proven otherwise — STOP the drug, call ICU and ophthalmology, and calculate SCORTEN.[1][9]

The unifying concept — acute skin failure

Think of the skin as an organ that can fail, exactly like the kidney or the lung. When it fails across a large surface area the consequences are identical to a burn: fluid and electrolyte loss, protein loss, hypothermia, sepsis, and high-output cardiac failure.[1][2]

The examiner's distinction that earns marks is between a bad rash (uncomfortable but self-limiting) and a skin emergency (death or permanent disability within hours). The whole topic is the bedside skill of telling them apart on inspection.[1]

Four mechanisms, one first response

The conditions group into four mechanisms — but the first response is always the same. [1]

[1]

The first response never waits for a biopsy: ABCDE, stop every drug started in the last eight weeks, fluid resuscitate, give IV antibiotics for purpura with fever, call surgery for necrosis, protect the airway for angioedema. The dermatologist is called early but does not own the first hour.[1]

The two governing principles

First: a febrile patient with a rash and systemic upset is assumed to have a dermatological emergency until proven otherwise. The cost of missing meningococcaemia or TEN is death; the cost of over-calling a viral exanthem is a brief admission.[1]

Second: recognition and resuscitation precede diagnosis. The immediate actions are taken on the clinical pattern alone, before biopsy, cultures, or specialist review confirm the specific entity. Diagnose on the move; the patient is dying while you deliberate.[1][2]

Epidemiology & Risk Factors

The high-risk drugs, host factors, and mortality figures are exactly what examiners probe. SJS and TEN are rare but feared: combined incidence is roughly 1 to 6 per million person-years, drugs are implicated in over 80 percent, and mortality climbs steeply with the percentage of detached epidermis.[10]

DRESS is an order of magnitude commoner — about 1 per 1000 to 10000 drug exposures — with a case-fatality of 5 to 10 percent, most often from fulminant hepatitis.[7]

[4]

Staphylococcal scalded skin syndrome overwhelmingly affects neonates and children under 5, where mortality is about 4 percent. In adults — typically those with renal failure or immunocompromise — it climbs to over 50 percent because the toxin cannot be renally cleared.[4]

Necrotising fasciitis incidence is rising, driven by diabetes, obesity, immunosuppression, intravenous drug use, and ageing populations. Mortality is 20 to 40 percent and is halved by surgical debridement within 24 hours.[11]

Erythroderma shows a male preponderance with a mean onset over age 40, and an underlying cause is eventually identified in about 70 percent — a pre-existing dermatosis, a drug, or a malignancy such as cutaneous T-cell lymphoma.[8]

The risk factors for a severe drug reaction are the viva staples: a personal or family history of drug hypersensitivity; specific HLA alleles (HLA-B*15:02 with carbamazepine in Han Chinese and South-East Asians; HLA-B*58:01 with allopurinol); active viral infection (HIV, EBV, CMV) which lowers the reaction threshold; renal or hepatic impairment; and high cumulative drug dose.[6]

Pathophysiology — name the molecule, not "allergy"

The examiner rewards the candidate who names the molecular target rather than says "it is an allergic reaction." Each emergency has a distinct, examinable mechanism.[1]

Stevens-Johnson syndrome and TEN are drug-induced, full-thickness keratinocyte apoptosis. The dominant effector is granulysin, a cytotoxic molecule released by drug-specific CD8-positive T cells and natural killer cells; Fas-Fas ligand, perforin/granzyme, and tumour necrosis factor contribute. The result is confluent epidermal necrosis with a subepidermal split, leaving a denuded, bleeding dermis analogous to a thermal burn.[10]

SSSS is toxin-mediated, not T-cell-mediated. Phage group II Staphylococcus aureus at a distant focus (conjunctivitis, otitis, a wound) produces exfoliative toxin A or B, which circulates haematogenously and cleaves the extracellular domain of desmoglein-1 in the stratum granulosum. The split is high and superficial — only the uppermost epidermis separates.[4]

Because desmoglein-3 compensates in mucosal epithelium, the mucosae are spared — and that is the cardinal distinction from SJS/TEN.[5]

DRESS/DIHS is a systemic drug hypersensitivity with a characteristic 2 to 8 week latency. The mechanism combines drug-specific T-cell activation, a defect in detoxification of reactive metabolites (sulphonamides, anticonvulsants), and reactivation of human herpesviruses — most consistently HHV-6, but also CMV and EBV — which drives the biphasic, relapsing course and the eosinophilia.[7]

AGEP is the fastest-onset severe cutaneous drug reaction. Drug-specific CD4-positive T cells home to the epidermis and release IL-8 (CXCL8), a potent neutrophil chemoattractant. Neutrophils fill the subcorneal space as sterile, culture-negative pustules. The lack of deep necrosis explains the low mortality and rapid resolution once the drug is withdrawn.[2]

Erythroderma is a failure of epidermal turnover and barrier function. Massive cutaneous vasodilation over a large surface area produces continuous insensible loss of water, electrolytes, and protein; heat loss causes shivering and hypothermia; and the persistent vasodilation generates a hyperdynamic circulation that can precipitate high-output cardiac failure in the elderly.[8]

Necrotising fasciitis is a spreading infection of subcutaneous tissue and deep fascia that initially spares muscle and overlying skin. Three microbiological types: Type I polymicrobial (anaerobes plus Gram-negatives, after surgery or in diabetics); Type II monomicrobial Group A streptococcal after minor trauma; and Type III marine (Vibrio vulnificus, Aeromonas) after seawater exposure. Tissue destruction is driven by direct invasion plus exotoxins that produce a toxic-shock phenotype.[11]

Purpura fulminans is DIC localised to the dermal microvasculature. Microthrombi occlude dermal capillaries and venules, producing haemorrhagic infarction in a characteristic retiform (net-like, stellate) pattern that progresses to full-thickness necrosis. The three settings are neonatal homozygous protein C deficiency, acute infectious (overwhelming meningococcaemia), and idiopathic post-infectious with acquired protein S deficiency.[13]

Hereditary angioedema is a deficiency (Type I, 85 percent) or dysfunction (Type II, 15 percent) of C1 esterase inhibitor. Unopposed activation of the contact pathway generates excess bradykinin, the dominant mediator. Because the swelling is bradykinin-mediated rather than histamine-mediated, conventional anaphylaxis therapy — adrenaline, antihistamines, corticosteroids — is largely ineffective.[15][16]

Clinical Presentation — recognise on inspection

Erythroderma (exfoliative dermatitis)

The definition is erythema and scaling over more than 90 percent of the body surface area. Patients shiver, feel cold, and describe tightness; the skin is diffusely red, warm, and scaling, with oedema, fissuring, and palmoplantar keratoderma.[8]

Lymphadenopathy (dermopathic) is common, and ectropion and alopecia may accompany chronic disease. The acute danger signs are tachycardia, hypotension, oliguria (hypovolaemia), confusion (hypothermia or sepsis), and respiratory distress from high-output cardiac failure.[8]

Stevens-Johnson syndrome / toxic epidermal necrolysis

A flu-like prodrome is followed by a macular, targetoid, or purpuric rash that coalesces and then detaches. Classification is by percentage of detached epidermis.[10]

[10]

Mucosal involvement — oral, conjunctival, tracheobronchial, genital, urethral — is present in over 90 percent and is the single most reliable discriminator from SSSS. Positive Nikolsky and Asboe-Hansen signs show the cleavage plane has extended. Skin pain and tenderness are prominent; the patient looks systemically unwell.[10]

DRESS / DIHS

The presentation is a triad — fever, rash, and internal organ involvement — beginning 2 to 8 weeks after drug exposure. The rash is morbilliform, becoming infiltrated and oedematous, with characteristic facial oedema as a clue.[7]

Generalised lymphadenopathy is common. Visceral involvement drives the severity: hepatitis (the leading cause of death), interstitial nephritis, pneumonitis, myocarditis, colitis. Eosinophilia (often over 1.0 x 10^9/L) and atypical lymphocytes support the diagnosis. The course is often biphasic, relapsing as the corticosteroid is tapered — the footprint of ongoing viral reactivation.[7]

AGEP (Acute Generalised Exanthematous Pustulosis)

Hundreds of small, sterile, non-follicular pustules erupt on an erythematous base within under 4 days of a drug (penicillins, macrolides). Fever and leucocytosis accompany the rash; mucosal involvement is minimal; systemic organ involvement is uncommon.[2]

The condition is usually self-limiting once the drug is withdrawn, resolving with desquamation over 1 to 2 weeks. The EuroSCAR validation score separates AGEP from pustular psoriasis: rapid onset under 4 days, a typical culprit, hundreds of non-follicular pustules, and a neutrophilic (not lymphocytic) infiltrate all score for AGEP. Mortality is under 5 percent — far lower than SJS/TEN or DRESS.[2]

Staphylococcal scalded skin syndrome

In an infant or child under 5, a focal staphylococcal infection is followed by systemic spread of exfoliative toxin. The sequence: diffuse tender erythema, then large flaccid bullae that rupture easily, then sheet-like peeling leaving a moist, glistening, scalded surface.[4]

The Nikolsky sign is positive. The mucosae are spared — oral, conjunctival, and genital — because desmoglein-3 maintains mucosal integrity. That single feature is the bedside fork from SJS/TEN.[5]

Necrotising fasciitis

The red flag is pain grossly disproportionate to the visible skin signs. Early, the skin may show only mild erythema and oedema indistinguishable from cellulitis; over hours the erythema spreads rapidly, the skin turns dusky and indurated, bullae form (haemorrhagic bullae are ominous), and cutaneous anaesthesia develops as nerves are infarcted.[11]

Crepitus may be present in gas-forming infection. Systemically the patient develops high fever, tachycardia, hypotension, altered mental state, and multi-organ failure — a toxic-shock picture out of proportion to the visible lesion.[11]

Purpura fulminans / meningococcaemia

The rash begins as small petechiae and rapidly coalesces into retiform (net-like, geographic) purpura with sharply demarcated, dusky edges that progress to frank cutaneous necrosis, especially on the extremities.[13]

This is accompanied by fever, shock, and signs of DIC. In meningococcal disease there may be meningism, but meningococcaemia can occur without meningitis. The rash with fever is the trigger to treat now, not to investigate.[13]

Generalised pustular psoriasis (von Zumbusch)

An explosive eruption of widespread, sterile, pinpoint pustules on intensely erythematous skin, with high fever, rigors, malaise, and marked leukocytosis. The patient is erythrodermic and unwell; pustules coalesce into lakes of pus and then desquamate.[14]

There may be a history of chronic plaque psoriasis. Precipitants include systemic corticosteroid withdrawal, infections, pregnancy (impetigo herpetiformis), hypocalcaemia, and irritating topical therapy.[14]

Angioedema / anaphylaxis

Rapidly progressive, non-pitting swelling of the deep dermis and subcutis, most dangerous at the lips, tongue, floor of mouth, and larynx — stridor, drooling, respiratory distress. Histamine-mediated angioedema (allergic/anaphylaxis) comes with urticaria, itch, bronchospasm, hypotension.[15]

Bradykinin-mediated angioedema (hereditary, acquired, ACE-inhibitor) causes episodic swelling without urticaria, pruritus, or hypotension, and tends to be slower but more refractory. Recurrent, unexplained, non-urticarial swellings are the clue to HAE.[16]

Toxic shock syndrome

TSS is a toxin-mediated superantigen emergency, not a direct skin infection. Menstrual TSS (tampon-associated, TSST-1) and non-menstrual TSS (post-surgical, post-burn) present with abrupt high fever, hypotension, a diffuse sunburn-like macular erythroderma, conjunctival and mucosal hyperaemia, strawberry tongue, and multi-organ failure. Desquamation of palms and soles follows in 1 to 2 weeks.[1]

Streptococcal toxic shock (Group A strep, often with necrotising fasciitis) is clinically similar but bacteraemic and rapidly progressive. Management is aggressive fluid resuscitation, source control, IV antibiotics (clindamycin to suppress toxin), and IVIG for severe cases.[1]

Differential Diagnosis — four discriminating questions

The differentials cluster around four high-yield questions: is the mucosa involved? What is the cleavage plane? What is the latency from drug to rash? Is there systemic toxicity?[1]

The single most tested distinction is SSSS versus SJS/TEN — and the discriminator line is the mucosa:[4]

[4] [10]

For the drug-reaction latency question, the discriminator is time:[7]

[2]

For a rapidly spreading painful red leg, the discriminator for necrotising fasciitis is the combination of severe pain out of proportion, rapid progression, and systemic toxicity — against cellulitis (slow, well-demarcated), erysipelas (sharply raised), gas gangrene (clostridial, crepitus, bronze), and calciphylaxis (renal failure, painful necrotic ulcers with livedoid edges).[11]

For erythroderma, the cause categories fall in roughly equal thirds: pre-existing dermatosis (psoriasis, eczema, pityriasis rubra pilaris), drug reaction, and underlying disease (CTCL/Sézary, pemphigus foliaceus, ichthyosiform), with idiopathic the remainder.[1]

Clinical & Bedside Assessment

Every suspected dermatological emergency is assessed first by ABCDE, then by a focused skin examination. The airway is the immediate threat in angioedema with laryngeal involvement and in SJS/TEN with tracheobronchial sloughing.[1]

Breathing may be compromised by bronchospasm (anaphylaxis) or the hyperdynamic pulmonary oedema of erythroderma. Circulation is threatened by hypovolaemia (erythroderma, SSSS, SJS/TEN all lose fluid through denuded skin) and by distributive shock (necrotising fasciitis, purpura fulminans). Disability reflects hypothermia or septic encephalopathy. Exposure is the dermatological examination itself.[1]

[1]

In necrotising fasciitis, feel for the "hardwood" induration — loss of normal subcutaneous softness, a woody-hard tissue that distinguishes it from cellulitis. Look for a portal of entry (trauma, surgical wound, IV cannula, fissure) and palpate for crepitus.[11] Bedside ultrasound can add confidence here — a thickened, fuzzy deep fascia with fluid and subcutaneous gas supports necrotising fasciitis, and high-frequency sonography helps gauge bulla depth in the blistering eruptions — but it never replaces the theatre decision in a toxic patient.[3]

In suspected DRESS, examine the face for oedema, palpate all lymph node groups, and feel for hepatomegaly. In suspected HAE, ask about family history, recurrent unexplained abdominal pain (bowel-wall oedema), and episodes triggered by dental work or trauma; measure the swelling velocity.[1]

Investigations — support, never delay

Investigations support but never delay treatment in the time-critical conditions. The named scores are reproduced verbatim because they are the examinable material.[1]

SCORTEN (severity of illness for TEN)

Calculated at 24 hours and again at 72 hours after admission. Each criterion scores one point; the sum predicts mortality.[9]

[9] [9]

RegiSCAR criteria (DRESS/DIHS diagnosis)

A scoring system that classifies a case as definite, probable, possible, or no DRESS from the pattern of features.[6]

The components are: fever over 38.5 degrees C; rash (extent over 50 percent BSA, oedema, infiltration, purpura, desquamation); eosinophilia (over 0.7 x 10^9/L, or over 10 percent if leucopenic) or atypical lymphocytes; enlarged lymph nodes (at least two sites, over 1 cm); internal organ involvement (hepatitis, interstitial nephritis, pneumonitis, myocarditis); resolution of the suspected drug within 15 days; and exclusion of infectious and autoimmune causes.[6]

LRINEC score (laboratory risk indicator for necrotising fasciitis)

A score of 6 or more suggests necrotising fasciitis; a score of 5 or less does not exclude it. Clinical judgement overrides the score, and a low score must never delay surgery in a toxic patient.[11][12]

[11]

Biopsy and laboratory

In SSSS, a skin biopsy with frozen section shows a superficial intraepidermal split at the stratum granulosum — no necrosis, no inflammation, no organisms. That distinguishes it from SJS/TEN (full-thickness necrosis) and bullous impetigo (subcorneal pustules with organisms).[4]

In SJS/TEN, biopsy shows full-thickness epidermal necrosis with a sparse infiltrate. A shave or punch biopsy is performed but must not delay treatment.[1]

In DRESS, the laboratory phenotype drives diagnosis and monitoring. Send full blood count with differential (eosinophilia, atypical lymphocytes), liver function (ALT/AST over 2 to 5 times ULN; rising bilirubin and INR signal fulminant hepatitis), renal function and urinalysis (interstitial nephritis with sterile pyuria), and CK and troponin if myocarditis is suspected. Where available, quantitative HHV-6, CMV, and EBV PCR at baseline and weekly — rising titres confirm the diagnosis and warn of imminent flare as corticosteroids taper.[7]

In necrotising fasciitis, the operative finding is the investigation: foul-smelling "dishwater" fluid, grey necrotic fascia that separates easily (positive "finger test"), thrombosis of perforating vessels, and lack of bleeding from the fascia. Tissue and deep wound cultures (not superficial swabs) guide therapy; blood cultures are positive in up to 25 percent of Type II streptococcal disease. Imaging is reserved for the haemodynamically stable patient with an ambiguous presentation — in a classic toxic patient, theatre is the investigation.[11]

In purpura fulminans, send coagulation (PT, APTT, fibrinogen, D-dimer), full blood count with blood film (schistocytes suggest microangiopathy), blood cultures (meningococcus, pneumococcus), and protein C, protein S, and antithrombin drawn before transfusion. Biopsy shows dermal microvascular thrombosis with full-thickness infarction and scant inflammation — the paucity of inflammation distinguishes it from leukocytoclastic vasculitis.[13]

Rapid Assessment Algorithm

ABCDE and vitals come first; the skin examination then drives the immediate action set.[1]

[1]

Management — the resuscitation phase

The resuscitation phase is identical in principle across all dermatological emergencies — it is what the patient is dying of while you make the diagnosis.[1]

A — Airway. Angioedema with stridor, drooling, or tongue swelling needs early anaesthetic and ENT involvement; prepare for awake fibre-optic intubation or surgical airway. In SJS/TEN with tracheobronchial involvement, anticipate a difficult, bleeding airway.[1]

B — Breathing. High-flow oxygen; bronchodilators for bronchospasm (anaphylaxis); monitor for pulmonary oedema in erythroderma.[1]

C — Circulation. Two large-bore IV cannulae. In erythroderma, SSSS, and SJS/TEN, fluid losses through denuded skin are enormous and burn-equivalent — resuscitate with warmed crystalloid guided by urine output (over 1 mL/kg/h) and haemodynamics. In necrotising fasciitis and purpura fulminans, treat distributive and septic shock with crystalloid boluses, vasopressors (noradrenaline), and early IV antibiotics. In anaphylaxis, give IM adrenaline 0.5 mg (500 micrograms) into the anterolateral thigh, repeated at 5 minutes if no response, with IV fluid support.[2]

D — Disability. Correct hypothermia (warmed fluids, forced-air warming, ambient temperature up); glucose; treat seizures.[1]

E — Exposure and Environment. Fully expose the skin (then cover to preserve heat), examine, and document BSA and detachment. Stop all new drugs started within 8 weeks. Decubitus care, eye care (ophthalmology within hours for SJS/TEN), and catheterisation (SJS/TEN with urethral involvement) are part of resuscitation, not an afterthought.[1]

Management — Definitive and Stepwise

SJS / TEN

The bundle is supportive first, immunomodulation second — and STOP the drug is the one intervention everyone agrees on.[1]

[1]

The classic trap: the 2022 Cochrane review found no agent — corticosteroids, IVIG, ciclosporin, plasmapheresis, thalidomide — with proven mortality benefit, and randomised evidence is sparse. Treatment remains supportive with centre-specific immunomodulation. Prophylactic antibiotics do not prevent sepsis and increase resistance; treat only documented infection.[10]

DRESS / DIHS

Stop the drug and start systemic corticosteroids, then plan a slow taper — because relapse is the rule as HHV-6 reactivates.[7]

Use oral prednisolone 1 mg/kg/day (or IV methylprednisolone 0.5 to 1 mg/kg/day if severe), tapering over weeks to months. Treat organ failure supportively. In corticosteroid-refractory or dependent disease, ciclosporin, mycophenolate, or IVIG have been used. Re-challenge is absolutely contraindicated. Taper guided by eosinophil count, liver function, and clinical signs; consider a steroid-sparing agent at 4 to 6 weeks.[7]

Staphylococcal scalded skin syndrome

Anti-staphylococcal antibiotic, fluids, and gentle wound care — and never debride, because the split is superficial and re-epithelialises.[4]

[4]

Skin generally heals within 1 to 2 weeks without scarring because the split is superficial. Adults with SSSS have a much worse prognosis and need ICU-level care and renal-dose-adjusted antibiotics to clear the toxin.[4]

Erythroderma

Admit and manage like a burn: fluids, temperature, emollients, sepsis watch, thromboprophylaxis, and treat the cause.[8]

Fluid and electrolyte management is central — IV crystalloid to replace ongoing losses, with daily weighing and urine output monitoring. Keep the ambient temperature high (over 28 degrees C), use warmed fluids and forced-air warming, and avoid overheating. Apply emollients frequently and mild to mid-potency topical corticosteroids (avoid potent corticosteroids over large areas due to systemic absorption). Monitor for and treat sepsis; give thromboprophylaxis with low-molecular-weight heparin because erythroderma is a prothrombotic state.[8]

Necrotising fasciitis

This is a surgical emergency. The definitive treatment is emergency surgical debridement of all necrotic tissue down to bleeding, healthy muscle and fascia, with a low threshold for re-look debridement at 24 to 48 hours.[11]

Antibiotics are adjunctive and started immediately: empiric broad-spectrum cover such as piperacillin-tazobactam 4.5 g IV eight-hourly plus clindamycin 600 mg IV eight-hourly (to suppress toxin production) for polymicrobial disease, or benzylpenicillin plus clindamycin for Group A streptococcal disease; add vancomycin if MRSA is possible. IV immunoglobulin and hyperbaric oxygen are adjuncts without strong evidence. Vasopressor and ventilatory support as needed for septic shock.[11]

Purpura fulminans

Treat the underlying cause aggressively, and give the antibiotic before the blood culture. For meningococcal disease give IV ceftriaxone 2 g (adult) or 50 to 100 mg/kg (child) immediately — do not wait for investigations.[13]

Supportive care for DIC and shock: fresh frozen plasma to replace consumed clotting factors and protein C/S, protein C concentrate or activated protein C where available, and antithrombin in some protocols. The necrotic skin requires surgical assessment for fasciotomy, escharotomy, and eventual debridement and grafting; amputation rates are high in survivors.[13]

Generalised pustular psoriasis (von Zumbusch)

Admit; mortality is from sepsis, hypocalcaemia, and high-output cardiac failure. Systemic retinoid is first-line and acts rapidly.[14]

Acitretin 0.5 to 1 mg/kg/day is first-line. Alternatives where rapid control is needed are ciclosporin 3 to 5 mg/kg/day (fast onset, useful in pregnancy where retinoids are contraindicated) or infliximab 5 mg/kg at weeks 0, 2, and 6 (very rapid, for refractory disease). Avoid topical irritants, coal tar, and systemic corticosteroids (withdrawal precipitates pustular flares). Treat precipitants, correct hypocalcaemia, monitor fluid balance, and give thromboprophylaxis.[14]

Angioedema / anaphylaxis

The critical decision is whether the swelling is histamine- or bradykinin-mediated — because the treatments are entirely different.[15]

[15]

The classic trap: adrenaline works for histamine-mediated anaphylaxis but not for hereditary angioedema, which requires a bradykinin-pathway antagonist. Giving escalating adrenaline to refractory angioedema without urticaria or hypotension is a recurring error — think HAE and reach for icatibant or C1-INH concentrate.[15][16]

Calciphylaxis (calcific uraemic arteriolopathy)

Included as the vascular dermatological emergency of the dialysis patient: painful, stellate-livedoid, necrotic skin ulcers over areas of subcutaneous fat (abdomen, thighs, breasts) with calcification of small subcutaneous vessels on biopsy. Mortality is 50 to 80 percent at one year, usually from sepsis.[2]

Management is wound care, optimisation of calcium-phosphate metabolism (switch to a non-calcium phosphate binder, adequate dialysis), sodium thiosulphate IV during dialysis, and aggressive treatment of any infection. There is no proven cure.[2]

Specific Subtypes & Scenarios

Erythroderma by aetiology. The dermatosis group (psoriasis, eczema, pityriasis rubra pilaris) is treated by intensifying the underlying therapy. The drug group withdraws the culprit (sulphonamides, antiepileptics, gold, penicillin, allopurinol). The malignancy group — above all cutaneous T-cell lymphoma (Sézary syndrome) — needs systemic oncology therapy. The idiopathic group needs long-term surveillance, because a lymphoma may declare itself months to years later.[8]

Necrotising fasciitis by type. Type I polymicrobial occurs after surgery, in diabetics, and in the perineum (Fournier gangrene). Type II monomicrobial Group A streptococcal follows minor trauma, varicella, or IV drug use, often with streptococcal toxic shock. Type III marine (Vibrio vulnificus, Aeromonas) follows seawater or raw seafood exposure, especially in liver disease, and runs a fulminant course.[1]

Angioedema by mechanism. HAE Type I (low C1-INH antigen and function, 85 percent) and Type II (normal antigen, low function, 15 percent) are autosomal dominant. Acquired angioedema is associated with B-cell lymphoproliferative disease or autoantibodies to C1-INH. ACE-inhibitor angioedema is increasingly common, occurs months to years after starting the drug, is bradykinin-mediated, and responds to drug cessation plus icatibant in severe cases.[16]

Purpura fulminans by setting. Neonatal purpura fulminans is homozygous protein C deficiency presenting with DIC and skin necrosis in the first days of life; treat with protein C concentrate and FFP. Acute infectious purpura fulminans complicates overwhelming meningococcaemia, pneumococcaemia, or varicella. Idiopathic post-infectious purpura fulminans follows a viral illness with autoantibodies to protein S.[13]

Pemphigus vulgaris as a dermatological emergency. Widespread flaccid bullae, painful oral erosions that prevent eating, and extensive skin denudation — the positive Nikolsky sign and suprabasal acantholysis on biopsy (with intercellular IgG/C3 on DIF) distinguish it from SJS/TEN. The emergency is fluid and electrolyte loss, sepsis, and malnutrition. Treatment is high-dose systemic corticosteroids (prednisolone 1 to 1.5 mg/kg/day) plus rituximab 375 mg/m^2 weekly for 4 weeks (now first-line for moderate-severe disease), with wound care and analgesia.[2]

Kawasaki disease (mucocutaneous lymph node syndrome). A paediatric vasculitis emergency because untreated coronary artery aneurysms develop in up to 25 percent. The criteria are fever for at least 5 days plus four of five: bilateral non-purulent conjunctivitis, oral changes (strawberry tongue, cracked lips), polymorphous rash, extremity changes (erythema of palms/soles, periungual desquamation later), and cervical lymphadenopathy.[1]

Treatment is IVIG 2 g/kg as a single infusion plus aspirin, ideally within the first 10 days of fever to prevent coronary aneurysms. A red strawberry tongue with a peeling rash and fever in a child is Kawasaki until proven otherwise.[1]

Complications & Pitfalls

Erythroderma causes hypothermia, hypovolaemia, hypoalbuminaemia, high-output cardiac failure, hypothermia-induced coagulopathy, sepsis from skin organisms, and venous thromboembolism (a recognised hypercoagulable state).[8]

SJS/TEN causes corneal adhesions, symblepharon, and blindness (the leading cause of long-term disability); oesophageal, urethral, vaginal, and bronchial strictures; cutaneous scarring and dyspigmentation; nail dystrophy and loss; and death from sepsis or multi-organ failure. Early and daily ophthalmology is non-negotiable.[1]

SSSS causes dehydration, electrolyte disturbance, hypothermia, and secondary infection. The classic errors are confusing it with SJS/TEN and treating with corticosteroids rather than flucloxacillin, and debriding skin that will re-epithelialise.[4]

Necrotising fasciitis causes limb loss, multi-organ failure, and death. The classic errors are sending the patient for CT/MRI and waiting for the report, attributing severe pain to a "bad cellulitis," and inadequate initial debridement.[11]

DRESS causes fulminant hepatitis (the leading cause of death), renal failure, pneumonitis, and myocarditis; the relapsing course on corticosteroid taper and autoimmune sequelae (thyroiditis, type 1 diabetes) are often under-appreciated.[7]

Prognosis & Disposition

Prognosis is captured by the named scores. SCORTEN at 72 hours is the most accurate mortality predictor for TEN — a score of 0 to 1 carries roughly 3 percent mortality; a score of 5 or more, over 90 percent.[9]

SSSS mortality is about 4 percent in children but over 50 percent in adults with renal failure or immunocompromise. Necrotising fasciitis mortality is 20 to 40 percent, halved by surgical debridement within 24 hours; amputation rates reach 20 to 30 percent in survivors.[11]

DRESS mortality is 5 to 10 percent, driven by hepatitis. Purpura fulminans mortality is high (up to 40 percent for meningococcal, higher with multi-organ failure), and survivors have a significant amputation rate. Calciphylaxis carries a one-year mortality of 50 to 80 percent.[13]

Disposition thresholds. Admit to ICU or a burns unit any SJS/TEN with epidermal detachment over 10 percent BSA, SCORTEN over 2, or comorbidity; admit erythroderma if unstable; admit all necrotising fasciitis and purpura fulminans to a surgical or critical care environment; admit DRESS with hepatitis or renal failure. All patients need dermatology referral, and SJS/TEN needs ophthalmology within hours.[1]

Special Populations

Paediatric. The dermatological emergencies of childhood are distinct: SSSS (staph toxin, mucosa spared, flucloxacillin), Kawasaki disease (coronary vasculitis, IVIG plus aspirin), toxic shock, neonatal emergencies, and varicella complicated by Group A streptococcal necrotising fasciitis. Doses are weight-based: flucloxacillin 25 to 50 mg/kg/day in four divided doses, ceftriaxone 50 to 100 mg/kg (avoid in neonates under 28 days — use cefotaxime), IVIG for Kawasaki 2 g/kg over 10 to 12 hours, adrenaline 10 micrograms/kg IM, aciclovir 20 mg/kg IV for suspected neonatal herpes.[1]

Pregnancy. Systemic retinoids (acitretin, isotretinoin) are absolutely contraindicated (teratogenic); use ciclosporin or infliximab for von Zumbusch pustular psoriasis in pregnancy (impetigo herpetiformis). Penicillins and cephalosporins are safe. IVIG crosses the placenta and is safe. Avoid tetracyclines and sulphonamides in the third trimester (kernicterus), and chloramphenicol.[1]

Elderly and immunocompromised. The inflammatory response is blunted, so skin signs may be subtle (less fever, less erythema) while the systemic insult is severe — a high index of suspicion is essential. Drug reactions accumulate with polypharmacy; re-check every drug started in the last 8 weeks. Renal impairment prolongs flucloxacillin and ciclosporin exposure; dose-adjust.[1]

Renal failure and dialysis. Calciphylaxis is the dermatological emergency of this group. SSSS in adults occurs here because the exfoliative toxin is not cleared. Icatibant and C1-INH are used without dose adjustment; flucloxacillin and piperacillin-tazobactam need renal dose adjustment.[1]

Anticoagulated patients. Warfarin and direct oral anticoagulants complicate the bleeding of skin failure and the surgery of necrotising fasciitis; reverse per protocol before emergency debridement. Warfarin is itself a risk factor for calciphylaxis-like calcific arteriolopathy.[1]

Evidence, Guidelines & Regional Differences

The 2022 Cochrane review of systemic interventions for SJS/TEN found no agent with proven mortality benefit — corticosteroids, IVIG, ciclosporin, plasmapheresis, anti-TNF, and thalidomide were all of uncertain benefit — and called for adequately powered randomised trials.[10]

[9]

Despite the Cochrane finding, IVIG (1 to 3 g/kg total) and ciclosporin are widely used in specialist centres; corticosteroid use has declined over concerns about sepsis and re-epithelialisation delay.[10]

The RegiSCAR consortium defined the high-risk drugs for SCAR across European registries: allopurinol (now the leading cause of SJS/TEN and DRESS in Europe and Asia, especially with HLA-B*58:01), anticonvulsants (carbamazepine with HLA-B*15:02 in Han Chinese; lamotrigine, phenytoin), antibacterial sulphonamides (co-trimoxazole), nevirapine, and oxicam NSAIDs.[6]

Genetic screening for these HLA alleles before prescribing is now guideline-mandated in several East Asian health systems.[6]

[1] [1] [1] [1]

Controversies. Whether corticosteroids help or harm in SJS/TEN remains debated; the role of prophylactic antibiotics is settled (no); LRINEC has poor sensitivity in early disease and must not reassure; sodium thiosulphate for calciphylaxis has weak evidence; and the optimal taper of corticosteroids in DRESS is empirical.[7][12]

The mantra and the memory devices

The mantra for every dermatological emergency: ABCDE, STOP the drug, resuscitate, then name the score.[1]

[1] [1]

Ward-round test

A 3-year-old has diffuse erythema, skin tenderness, and sheet-like peeling; the mouth is normal. Diagnosis and first treatment?

Staphylococcal scalded skin syndrome. The spared mucosa, superficial split, and age make it toxin-mediated, not SJS/TEN. First treatment is IV flucloxacillin, fluids, gentle wound care, and analgesia; do NOT debride and do NOT use corticosteroids. [4][5]

A febrile patient on day 18 of nevirapine has a morbilliform rash, facial oedema, and ALT 600. Diagnosis and the trap?

DRESS/DIHS. The 2 to 8 week latency, facial oedema, eosinophilia, and hepatitis are the fingerprint; HHV-6 reactivation drives the relapsing course. Stop the drug, start prednisolone 1 mg/kg/day, and plan a slow taper over weeks to months. The trap is tapering too fast and triggering relapse. [7]

Recurrent lip and tongue swelling with no urticaria, not responding to adrenaline. What is it and what works?

Hereditary angioedema — bradykinin-mediated, so adrenaline, antihistamines, and steroids fail. Give C1 esterase inhibitor concentrate 20 IU/kg IV or icatibant 30 mg subcutaneous. Check C4 (low) and C1-INH antigen and function to confirm the type. [15][16]

A diabetic has a red, painful leg with pain out of proportion to the redness, and a LRINEC score of 4. What now?

Necrotising fasciitis remains on the table — a low LRINEC does not exclude it. Clinical judgement overrides the score. Start broad-spectrum antibiotics (piperacillin-tazobactam plus clindamycin) and take the patient to theatre for emergency debridement; do not delay for imaging. [11][12]

References

1. [1]Gruver JR, Kirkorian AY. Pediatric dermatologic emergencies Curr Opin Pediatr, 2024.PMID 39400084
2. [2]Usatine RP, Sandy N. Dermatologic emergencies Am Fam Physician, 2010.PMID 20879700
3. [3]Wortsman X. Sonography of Dermatologic Emergencies J Ultrasound Med, 2017.PMID 28470978
4. [4]Gray L, Hansen AM, Cipriano SD Pediatric Staphylococcal Scalded Skin Syndrome: A Systematic Review of the Literature to Inform Work-Up and Management Pediatr Dermatol, 2025.PMID 40650480
5. [5]Leung AKC, Barankin B, Leong KF Staphylococcal-scalded skin syndrome: evaluation, diagnosis, and management World J Pediatr, 2018.PMID 29508362
6. [6]Kardaun SH, Sidoroff A, Valeyrie-Allanore L, et al. Drug reaction with eosinophilia and systemic symptoms (DRESS): an original multisystem adverse drug reaction. Results from the prospective RegiSCAR study Br J Dermatol, 2013.PMID 23855313
7. [7]Awad A, Goh MS, Trubiano JA Drug Reaction With Eosinophilia and Systemic Symptoms: A Systematic Review J Allergy Clin Immunol Pract, 2023.PMID 36893848
8. [8]Mastorino L, Leo F, Frigatti G, et al. Management of Erythrodermic Psoriasis with Systemic Therapies: A Systematic Review Am J Clin Dermatol, 2025.PMID 40856907
9. [9]Bastuji-Garin S, Fouchard N, Bertocchi M, et al. SCORTEN: a severity-of-illness score for toxic epidermal necrolysis J Invest Dermatol, 2000.PMID 10951229
10. [10]Jacobsen A, Olabi B, Langley A, et al. Systemic interventions for treatment of Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and SJS/TEN overlap syndrome Cochrane Database Syst Rev, 2022.PMID 35274741
11. [11]Fernando SM, Tran A, Cheng W, et al. Necrotizing Soft Tissue Infection: Diagnostic Accuracy of Physical Examination, Imaging, and LRINEC Score: A Systematic Review and Meta-Analysis Ann Surg, 2019.PMID 29672405
12. [12]Tarricone A, Mata K, Gee A, et al. A Systematic Review and Meta-Analysis of the Effectiveness of LRINEC Score for Predicting Upper and Lower Extremity Necrotizing Fasciitis J Foot Ankle Surg, 2022.PMID 34657810
13. [13]Klifto KM, Gurno CF, Grzelak MJ, et al. Surgical outcomes in adults with purpura fulminans: a systematic review and patient-level meta-synthesis Burns Trauma, 2019.PMID 31641673
14. [14]Marrakchi S, Puig L Pathophysiology of Generalized Pustular Psoriasis Am J Clin Dermatol, 2022.PMID 35061228
15. [15]Betschel SD, Banerji A, Busse PJ, et al. Hereditary Angioedema: A Review of the Current and Evolving Treatment Landscape J Allergy Clin Immunol Pract, 2023.PMID 37116793
16. [16]Sinnathamby ES, Issa PP, Roberts L, et al. Hereditary Angioedema: Diagnosis, Clinical Implications, and Pathophysiology Adv Ther, 2023.PMID 36609679