Erythroderma and thermoregulatory failure

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Erythroderma is widespread cutaneous inflammation with exfoliation, conventionally over 90% of the body surface. Confluent redness is readily seen in light skin but may be muted or recorded only as purple-brown darkening in richly pigmented skin. Scale, warmth, infiltration, swelling and a striking boundary from previous baseline remain visible. Hair loss, ectropion, palmoplantar keratoderma, nail dystrophy and enlarged nodes can evolve over weeks. The extent erases the morphology of the initiating disease, so photographs and records from before generalisation are unusually valuable.

The skin becomes a failing organ. Vasodilation redistributes blood and raises cardiac output; evaporation loses water and heat; exfoliation loses protein; inflammation increases metabolic demand; and fissured skin permits bacterial entry. The result may be hypothermia, dehydration or paradoxical oedema, hypoalbuminaemia, electrolyte disturbance, high-output cardiac failure, acute kidney injury and sepsis. Fluid is therefore titrated to physiology rather than automatically copied from a thermal-burn formula, especially in older people with heart or kidney disease.

Determining cause is iterative. Eczema and psoriasis remain common, but rapid onset after a new medicine, withdrawal of systemic corticosteroid, orange-red disease with islands of sparing and follicular papules, crusted erosions, burrows, blisters, severe lymphadenopathy or persistent infiltrated skin redirects the work-up. Cutaneous T-cell lymphoma may require several biopsies over time plus blood immunophenotyping and clonality studies. Early supportive care and investigation proceed together; neither waits for diagnostic certainty.

Key points

Erythroderma means erythema and scale affecting more than 90% of body surface area; it is a dangerous clinical state, not a final aetiological diagnosis.
In brown or black skin, erythema may appear violaceous, grey, dusky or mainly as warmth, oedema and altered texture; examine palms, soles, nails, scalp and mucosae in good light.
Barrier loss causes evaporative fluid and heat loss, protein loss, increased metabolism, cutaneous vasodilation and infection risk; apparently hot skin can coexist with a cold patient.
Common causes include eczema, psoriasis and medicines; pityriasis rubra pilaris, cutaneous T-cell lymphoma, pemphigus foliaceus, severe scabies and congenital disorders are important alternatives.
Establish the timeline before labels disappear: previous plaque distribution, islands of sparing, palmoplantar change, nail disease, severe itch, lymph nodes and every new or stopped medicine can discriminate.
Discuss urgently with dermatology; admit anyone physiologically compromised and have a low threshold for frailty, cardiac or renal disease, very rapid onset or unreliable home support.
Stabilisation uses a warm environment, gentle handling, bland greasy emollient, non-adherent care, nutrition and measured replacement guided by observations, weight, urine and electrolytes.
Stop plausible non-essential culprit medicines after a risk assessment, but do not abruptly withdraw long-term systemic corticosteroid or another essential drug without a safe alternative.
One biopsy can be non-specific because the final common inflammatory pattern obscures the cause; select active sites and repeat clinicopathological assessment when disease persists.
Avoid reflex systemic corticosteroid treatment of undifferentiated erythroderma, particularly possible psoriasis, because withdrawal can provoke rebound or pustular crisis.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Inflammatory dermatosis

Atopic, contact or seborrhoeic eczema and psoriasis can extend until individual plaques merge, particularly after infection, irritant exposure, treatment interruption or systemic corticosteroid withdrawal.

Medicine reaction

Antimicrobials, anticonvulsants, allopurinol and many other agents can produce rapidly generalising inflammation; latency, mucosal disease, eosinophilia and organ injury refine the severe-reaction differential.

Malignant infiltration

Cutaneous T-cell lymphoma, including Sézary syndrome, and less often other haematological malignancy may produce chronic itchy infiltrated erythroderma with nodes and blood involvement.

Uncommon skin disease

Pityriasis rubra pilaris, pemphigus foliaceus, severe crusted scabies, ichthyosis and other rare disorders become erythrodermic and may reveal distinctive residual morphology or history.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Barrier permeability rises
Inflammation and accelerated epidermal turnover disrupt stratum corneum, increasing water loss, fissuring, topical-drug absorption and microbial access across almost the entire surface.
2
Cutaneous vessels dilate
Widespread vasodilation shunts blood into skin and lowers systemic vascular resistance, provoking tachycardia and potentially high-output cardiac failure in limited cardiac reserve.
3
Heat evaporates
Large exposed inflamed area loses heat through radiation and evaporation, while impaired sweating and vasomotor control make temperature unstable despite a warm-feeling surface.
4
Protein and fluid escape
Exfoliation, exudation and capillary leak remove protein and water, creating hypoalbuminaemia, oedema, intravascular depletion, electrolyte disturbance and increased nutritional requirements.
5
Systemic inflammation accelerates demand
Cytokine-driven metabolism raises oxygen and calorie needs while discomfort, itch and mucosal disease reduce intake and sleep, amplifying frailty and organ decompensation.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Extent and surface

Confluent inflammation and scaling covers more than 90% of surface area, often with fissuring, shedding, oedema, warmth and loss of the original lesion pattern.

Skin-tone variation

Inflammation may be bright pink-red, deep red, violaceous, grey-brown or dusky; palpated heat, oedema, scale and comparison with unaffected baseline prevent colour-only underrecognition.

Physiological compromise

Shivering, low core temperature, tachycardia, postural or absolute hypotension, oliguria, confusion, breathlessness or rapidly increasing oedema indicates skin-organ failure.

Psoriatic clues

Previous plaques, scalp or extensor scale, nail pitting or onycholysis and recent systemic corticosteroid or treatment withdrawal support an unstable psoriatic cause.

Pityriasis rubra pilaris clues

Orange-toned inflammation, islands of unaffected skin, follicular papules on dorsal fingers or extensor surfaces and waxy palmoplantar keratoderma suggest pityriasis rubra pilaris.

Lymphoma clues

Persistent intense itch, marked infiltration, ectropion, palmoplantar keratoderma, alopecia and substantial nodes, especially without previous inflammatory dermatosis, raise cutaneous T-cell lymphoma.

Infection or skin lossRed flag

Fever, severe tenderness, honey crust, purulence, monomorphic erosions, pustules, blisters, mucosal lesions, focal necrosis or crepitus indicates a superimposed or alternative emergency.

Red flags requiring action

Core hypothermia, tachycardia, hypotension, oliguria, rapid oedema or weight gain, breathlessness, chest pain, confusion, painful erosions, pustulation, mucosal disease, fever, focal infection, abrupt medicine withdrawal or frailty requires emergency hospital assessment.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Physiological severity assessmentFirst step
Why
Detect thermoregulatory, circulatory, respiratory and renal failure immediately.
Interpretation and limitations
Record core temperature, heart rate, blood pressure, oxygen saturation, respiratory rate, mental state, weight, fluid balance and urine output repeatedly; trends dictate level of care.
02
Full blood count and film
Why
Identify infection, eosinophilia, anaemia and abnormal circulating lymphocytes.
Interpretation and limitations
Neutrophilia may reflect inflammation or infection, eosinophilia supports but does not prove a drug or atopic cause, and atypical lymphocytes require haematology and dermatology interpretation.
03
Renal, liver, bone and protein profile
Why
Measure dehydration, organ injury, electrolytes and protein loss.
Interpretation and limitations
Trend urea, creatinine, electrolytes, calcium, magnesium, liver tests and albumin; low albumin can drive oedema, while corrected calcium may conceal ionised disturbance.
04
Infection sampling
Why
Detect bacterial, viral, fungal or parasitic complications and mimics.
Interpretation and limitations
Culture blood when systemically unwell and sample exudate, fresh vesicles, scale, nails or burrows by morphology; colonisation from widespread broken skin needs clinical correlation.
05
Skin biopsy
Why
Look for psoriasis, eczema, drug reaction, PRP, immunobullous disease or lymphoma.
Interpretation and limitations
Biopsy a representative active site and add direct immunofluorescence from perilesional skin when blistering is suspected; non-specific histology should prompt repeat sampling, not false reassurance.
06
Lymphoma-directed studies
Why
Assess persistent unexplained erythroderma or suspicious nodes for cutaneous T-cell lymphoma.
Interpretation and limitations
Request blood film, flow cytometry, T-cell receptor clonality, LDH and node imaging or biopsy with a skin-lymphoma multidisciplinary team; isolated clonality is interpreted with phenotype and course.
07
Cardiorespiratory assessment
Why
Identify high-output failure, pulmonary oedema or another cause of decompensation.
Interpretation and limitations
Use ECG, chest imaging, natriuretic peptide, blood gas or echocardiography according to findings; tachycardia should not be attributed to skin inflammation before sepsis and heart failure are excluded.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Erythrodermic psoriasis

Prior plaques, nail dystrophy and a treatment-withdrawal trigger support psoriasis, although scale may disappear during acute severe inflammation and pustulation can supervene.

Eczematous erythroderma

Longstanding atopy, contact exposure, lichenification, flexural history and intense itch favour eczema, but widespread topical sensitisation can complicate the visible pattern.

Severe drug reaction

A recent medicine with fever, facial oedema, mucosal damage, epidermal pain, pustules, eosinophilia or internal-organ injury points toward a specific severe cutaneous adverse reaction.

Pityriasis rubra pilaris

Cephalocaudal orange-red spread, islands of sparing, follicular hyperkeratosis and waxy palmoplantar thickening distinguish PRP when these clues survive generalisation.

Cutaneous T-cell lymphoma

Persistent infiltrated itch, alopecia, ectropion, keratoderma, nodes and an abnormal blood phenotype raise mycosis fungoides or Sézary syndrome, often after initially equivocal biopsies.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01First-line stabilisationTreat the skin as a failing organFirst stepFirst lineErythroderma is suspected, especially with systemic symptoms or frailty.

1Measure extent and full observations including core temperature, perfusion, weight and urine, then involve acute medicine and the on-call dermatologist.
2Admit physiological compromise or high risk, use a warm humidified environment, gentle handling, non-adherent linen and regular bland ointment.
3Replace fluid, electrolytes and nutrition cautiously against repeated urine, weight, renal, albumin, respiratory and cardiac findings rather than a fixed volume.
4Culture suspected infection and treat sepsis promptly while providing thrombosis, pressure-area, eye and temperature protection appropriate to immobility and skin loss.

02Cause sequenceReconstruct before treating deeplyThe person is stabilised enough for a structured aetiological assessment.

1Retrieve earlier photographs and diagnoses and map onset, spread, pruritus, fever, weight loss and recent infection against all prescribed, non-prescribed and stopped medicines.
2Examine scalp, nails, palms, soles, folds, mucosae and nodes for psoriasis, PRP, scabies, immunobullous disease, drug reaction and lymphoma clues.
3Obtain baseline laboratory and lesion-directed microbial tests and one or more correctly sited biopsies, adding immunofluorescence or lymphoma studies when indicated.
4Stop non-essential plausible culprits safely and choose cause-directed systemic therapy only with dermatology after infection and unstable psoriasis risks are considered.

03Supportive skin careRestore barrier without adding harmWidespread dry, fissured or exudative skin needs immediate symptom control.

1Use a soap substitute, tepid brief washing and frequent bland ointment; avoid fragrance, irritant antiseptics, vigorous scale removal and adhesive trauma.
2Apply site-appropriate low or moderate potency topical corticosteroid in measured quantities only under dermatology direction because damaged skin increases absorption.
3Use wet wraps or dressings selectively with nursing expertise, monitor temperature and absorption, and keep paraffin-contaminated fabrics away from flames and smoking.

04Persistent erythrodermaRepeat the diagnostic loopInitial histology is non-specific or disease fails to resolve after removing a plausible cause.

1Revisit the medicine timeline, exposure history, scabies assessment and morphology emerging as inflammation settles, using serial standardised photographs with consent.
2Repeat biopsies from newly informative untreated sites and compare specimens in clinicopathological review rather than interpreting each report in isolation.
3EscalationEscalate persistent nodes, blood abnormalities, ectropion or infiltrated disease to the specialist skin-lymphoma team for integrated skin, blood and node assessment.

Key medicines and prescribing safety2 treatments · regimens, roles and cautions

Reduces transepidermal water loss, fissuring and discomfort while supporting recovery of a severely disrupted cutaneous barrier.

Bland paraffin-based emollient ointment

Apply generously to all dry intact skin every 2 to 4 hours and immediately after gentle washing, with quantities adjusted to surface area and exudation.

Paraffin-soaked clothing, bedding and dressings ignite readily even after washing; avoid flames and smoking, do not use a slippery bath unsupervised, and avoid application onto infected exudate without review.

Provides short-course low-potency anti-inflammatory treatment at absorption-prone sites while the underlying cause is being established.

Hydrocortisone 1% ointment

Apply a thin measured layer once or twice daily for 5 to 7 days to selected face or flexural inflammation, then reassess with dermatology.

Do not use as sole therapy for HSV, fungal or bacterial infection; widespread barrier failure increases systemic absorption, and periocular exposure, atrophy and diagnostic masking require careful site and duration control.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Thermoregulatory failure

Evaporative and radiant heat loss causes shivering and hypothermia, while infection or inflammation can also cause fever and rapid temperature swings.

Circulatory and cardiac failure

Vasodilation, fluid redistribution and increased output can cause hypotension, oedema, pulmonary congestion and decompensation, especially with previous ventricular or renal impairment.

Fluid, electrolyte and protein loss

Exfoliation and exudation produce dehydration, acute kidney injury, sodium or calcium disturbance, hypoalbuminaemic oedema, muscle loss and delayed barrier repair.

Secondary infection

Fissures and immune dysfunction permit cellulitis, bacteraemia, HSV dissemination and sepsis, which may initially resemble worsening inflammation rather than a focal infection.

Ocular and structural damage

Persistent inflammation can cause ectropion, exposure keratopathy, hair and nail loss, painful palmoplantar fissures, immobility, pressure injury and lasting pigmentary change.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Record core temperature, NEWS2 physiology, mental state and pain frequently until stable; warm skin or absence of fever cannot exclude hypothermia or sepsis.
Use daily weight, input, urine output, oedema, lung examination, renal function and electrolytes to balance replacement against pulmonary or high-output cardiac failure.
Inspect skin, pressure areas, lines, eyes and mucosae every day and culture new focal tenderness, exudate, vesicles or rapid deterioration rather than treating colonisation alone.
Trend albumin, nutrition and functional intake and involve dietetics early when exfoliation, exudation or mucosal pain creates sustained protein and energy loss.
Reassess the suspected cause as the surface pattern re-emerges and track medicine withdrawals, biopsy sites, pathology and specialist decisions on one timeline.
After discharge, arrange early dermatology follow-up, explicit relapse and infection warnings, topical quantities, emollient fire safety and outstanding lymphoma or allergy investigation.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Colour is not the definition

More than 90% inflamed surface plus scale defines the state; purple-brown darkening, warmth and oedema can be more informative than visible redness.

Hot skin loses heat

Cutaneous vasodilation and evaporation make the surface feel warm while core temperature falls, so measure rather than infer temperature.

Oedema can accompany depletion

Albumin loss and inflammation move fluid into tissue even when effective circulation is inadequate; weight, urine, lungs and perfusion guide replacement together.

Histology may mature later

A non-specific first biopsy reflects convergence of severe inflammation and does not exclude psoriasis, drug reaction, immunobullous disease or cutaneous lymphoma.

Nodes are not automatically malignant

Dermatopathic lymphadenopathy is common in extensive inflammation, but disproportionate, persistent or morphologically suspicious nodes still require tissue-directed assessment.

Systemic steroid can destabilise psoriasis

Rapid improvement may be followed by severe rebound or pustulation during withdrawal, making undifferentiated systemic corticosteroid use a hazardous shortcut.

11Common pitfallsFrequent interpretation and management errors.

01
Describing darkly pigmented erythrodermic skin as not red and therefore excluding dangerous inflammation.
02
Sending a cold, tachycardic patient home because the skin itself feels warm.
03
Applying an automatic thermal-burn fluid formula without accounting for cardiac, renal, urine and weight findings.
04
Starting systemic prednisolone before clarifying whether unstable psoriasis or infection is present.
05
Calling a single non-specific biopsy proof that lymphoma or immunobullous disease is absent.
06
Ignoring stopped medicines and abrupt systemic-treatment withdrawal when constructing the timeline.
07
Using fragranced products, aggressive scale removal or large quantities of potent topical steroid on a highly permeable barrier.
08
Discharging before physiology, intake and mobility are stable and the cause-directed follow-up pathway is named.