Erythroderma
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Direct answer
Erythroderma (exfoliative dermatitis) is generalised erythema with scaling affecting more than 90 per cent of the body surface area, arising from a pre-existing dermatosis such as psoriasis or eczema in most patients, from drugs, from cutaneous T-cell lymphoma, or remaining idiopathic. It is a dermatological emergency because the compromised skin barrier causes fluid and protein loss, temperature dysregulation, high-output cardiac failure, hypoalbuminaemia and secondary sepsis. Management is supportive — admission, emollients, moderate topical corticosteroids, monitoring of fluids, electrolytes and temperature — plus cause-directed therapy.
What you must remember
- Definition: confluent erythema with variable scaling, oedema and lichenification involving over 90 per cent body surface area; it may be acute over days or evolve over months.
- Commonest causes: exacerbation of a pre-existing dermatosis — psoriasis, atopic or contact dermatitis, seborrhoeic dermatitis — followed by drug reactions (anticonvulsants, sulphonamides, allopurinol, antibiotics, gold), malignancy (cutaneous T-cell lymphoma/mycosis fungoides, Sézary syndrome, leukaemias) and idiopathic disease.
- Systemic effects: shivering and hypothermia or fever from loss of thermoregulation; tachycardia and high-output cardiac failure from massive shunting; peripheral oedema; hypoalbuminaemia and negative nitrogen balance; electrolyte imbalance; generalised lymphadenopathy (dermopathic lymphadenopathy); increased risk of bacterial and fungal superinfection.
- Erythrodermic psoriasis is a recognised psoriasis variant and may be precipitated by abrupt withdrawal of systemic or potent topical corticosteroids, infections or irritating topical therapy.
- In an elderly male with long-standing unexplained erythroderma, lymphadenopathy, pruritus and nail changes, always consider Sézary syndrome — look for Sézary cells on the blood film and a raised CD4:CD8 ratio.
- Investigations: skin biopsy (multiple sites may be needed, repeated if unclear), full blood count with film, albumin and renal profile, cultures as indicated, and review of every drug the patient is on.
- Management: hospitalisation, warmed room, emollients liberally, medium-potency topical corticosteroids under occlusive dressings if needed, antihistamines for pruritus, fluid and protein replacement, antibiotic cover for proven infection, and definitive therapy for the underlying disease (for example, methotrexate, ciclosporin, acitretin or biologics for psoriasis; specific agents for lymphoma).
Common confusion
The frequently tested distinction is erythroderma of unknown cause in an older man (a setting where mycosis fungoides or Sézary syndrome must be actively excluded before labelling it idiopathic) versus drug-induced erythroderma (which usually begins as a morbilliform eruption two to three weeks after starting the culprit drug and may evolve to severe reactions). Students also conflate erythroderma with the red-man reaction to vancomycin infusion — the latter is a rate-dependent infusion reaction, not true exfoliative erythroderma. Finally, generalised pustular psoriasis may present on an erythrodermic background, and missing the waves of sterile pustules and fever changes management.
Exam-focused takeaway
The exam gives an elderly patient with head-to-toe redness and scaling, shivering, tachycardia and pedal oedema, then asks the most likely complication (high-output cardiac failure or hypothermia), the most likely underlying cause (pre-existing dermatosis, with psoriasis and eczema leading), or the immediate management step (admission with supportive care and emollients). Remember "more than 90 per cent BSA" as a one-liner and keep Sézary cells on the shortlist of diagnostic tests in unexplained persistent erythroderma.
Frequently asked questions
What defines erythroderma?
Confluent erythema with scaling involving more than 90 per cent of the body surface area, with or without oedema, lichenification and lymphadenopathy.
What is the most common cause of erythroderma?
Generalisation of a pre-existing dermatosis, most often psoriasis or eczema; drugs, lymphoma and idiopathic disease account for most of the remainder, with figures varying between series.
Why is erythroderma a medical emergency?
The leaky barrier causes fluid and protein loss, hypothermia, haemodynamic instability and high-output cardiac failure, and the broken skin invites sepsis — all potentially fatal without inpatient care.
What is dermopathic lymphadenopathy?
Generalised, usually painless lymph node enlargement secondary to longstanding skin inflammation; it is reactive, but persistent or hard nodes in erythroderma warrant biopsy to exclude lymphoma.
Which malignancy is classically associated with erythroderma?
Cutaneous T-cell lymphoma — mycosis fungoides in its tumour stage and especially the leukaemic variant, Sézary syndrome, which produces an erythrodermic, intensely pruritic patient with circulating malignant T-cells.
How is erythroderma treated initially?
Admission, temperature control, emollients, medium-potency topical corticosteroids, antihistamines, correction of fluid, electrolyte and albumin deficits, treatment of infection, and withdrawal of all suspect drugs while the cause is established.