DR12.1-5 | Eczemas Erythroderma Drug Reactions — Glossary

A delayed type IV hypersensitivity eczema occurring on re-exposure in a person already sensitised to a specific allergen (e.g. nickel, paraphenylenediamine, chromate); confirmed by patch testing.

Deep swelling of skin and mucosa that, when it threatens the airway, is a medical emergency requiring adrenaline and urgent transfer.

Dry, cracked 'crazy-paving' eczema of the lower legs in elderly patients, worse in winter and with over-washing.

A chronic, itchy endogenous eczema linked to inherited barrier dysfunction (e.g. filaggrin mutation) and atopy; flexural in children and adults, often with a personal or family history of asthma or allergic rhinitis.

Pinpoint bleeding seen when the scale of a psoriatic plaque is removed; a sign of psoriasis, not eczema, useful in differentiation.

The proportion of the total skin surface affected by a condition; erythroderma is defined by involvement of more than 90% BSA.

Management of TEN modelled on major-burn care — intravenous fluid resuscitation, gentle non-adherent wound care, warmth, analgesia and infection prevention — because the lost epidermal barrier behaves like burnt skin.

Identifying and immediately stopping the offending drug; the single most important step in managing every adverse drug reaction, possible anywhere and especially time-critical in SJS/TEN.

Any undesirable skin reaction caused by a drug, ranging from benign maculopapular rashes to life-threatening reactions such as DRESS and toxic epidermal necrolysis.

A malignancy of skin-homing T lymphocytes; its leukaemic, erythrodermic form is Sézary syndrome, an important malignant cause of erythroderma.

Widening of skin blood vessels; when generalised, as in erythroderma, it causes heat loss and increased cardiac workload.

A severe drug hypersensitivity syndrome with long latency (2–6 weeks), fever, facial oedema, lymphadenopathy, blood eosinophilia and internal organ involvement (most often hepatitis).

An itchy inflammatory skin condition characterised by erythema, vesicles and oozing when acute, and lichenification and scaling when chronic; classified by cause into endogenous and exogenous types.

A moisturiser that repairs the skin barrier and reduces water loss; the foundation of all eczema treatment, used continuously even when skin appears clear.

Eczema arising from the patient's own constitution rather than an external contactant; includes atopic, seborrhoeic, nummular, pompholyx, stasis and asteatotic eczema.

An elevated blood eosinophil count; a defining laboratory feature of DRESS and a clue to drug hypersensitivity.

A reaction producing classic target lesions, usually triggered by herpes simplex rather than drugs, with limited mucosal involvement; a key differential of SJS/TEN.

A generalised inflammatory skin disorder involving more than 90% of the body surface area, presenting with universal erythema, warmth and continuous scaling; a dermatological emergency because the skin can no longer regulate temperature, fluid and infection.

The continuous shedding of skin scale that characterises erythroderma and contributes to protein and fluid loss.

A synonym for erythroderma, emphasising the prominent generalised scaling and shedding of the skin.

Eczema caused by an external agent the skin contacts; comprises irritant and allergic contact dermatitis.

A cutaneous drug reaction producing one or a few well-defined dusky/violaceous plaques that recur at exactly the same site on each re-exposure to the culprit drug, leaving slate-grey post-inflammatory hyperpigmentation.

Heart failure occurring when the heart must pump an abnormally large volume; in erythroderma it is driven by extensive cutaneous vasodilation increasing venous return and cardiac demand.

An inherited human leukocyte antigen allele predisposing to a specific drug reaction (e.g. HLA-B15:02 with carbamazepine-induced SJS, HLA-B58:01 with allopurinol), relevant in Indian and East Asian populations.

A low serum albumin level; in erythroderma it results from protein lost in shed scale and exudate, lowering oncotic pressure and worsening oedema.

A dangerously low core body temperature; in erythroderma it results from heat loss through the widely vasodilated, inflamed skin and is an immediate threat to life.

Erythroderma in which no underlying cause is identified at presentation; accounts for about a quarter of cases until a cause declares itself.

Eczema from direct toxic damage to the skin barrier by an irritant (detergent, solvent, cement, wet work); needs no prior sensitisation and can affect anyone sufficiently exposed.

A potassium hydroxide preparation of a skin scraping examined under the microscope to detect fungal hyphae and confirm a dermatophyte infection.

The interval between starting a drug and the onset of the reaction; characteristically long (2–6 weeks) in DRESS, a feature that helps distinguish it from other reactions.

Thickening of the skin with exaggerated skin markings caused by chronic rubbing and scratching; the hallmark of chronic eczema.

The principle that the generalist initiates supportive and symptomatic treatment and refers, but does not start disputed or specialist-only therapies such as systemic corticosteroids in TEN.

The commonest, usually benign drug reaction: a widespread measles-like eruption of macules and papules that settles when the drug is withdrawn.

Shearing of the epidermis with light tangential pressure, indicating loss of epidermal cohesion; positive in SJS/TEN and pemphigus vulgaris.

A wound dressing that does not stick to the fragile denuded skin of TEN, used to protect the raw surface without causing further damage; debridement is avoided in primary care.

Endogenous eczema forming sharply marginated coin-shaped plaques, typically on the limbs.

A diagnostic test for allergic contact dermatitis in which standardised allergens are applied to the back under occlusion and read at 48 and 96 hours; a positive reaction reproduces localised eczema.

The systematic documentation and reporting of adverse drug reactions so that future harm is prevented; a duty in every adverse drug reaction, however mild.

An endogenous vesicular eczema producing deep-seated intensely itchy vesicles on the palms, soles and sides of the fingers.

Residual darkening of the skin at the site of resolved inflammation; in fixed drug eruption it marks the recurring lesion site between episodes.

Deliberate re-administration of a suspected culprit drug; contraindicated in drug reactions because re-exposure reliably reproduces and may worsen the reaction (e.g. a fixed drug eruption).

A severity-of-illness score for SJS/TEN combining age, extent of detachment, heart rate, malignancy and serum urea, glucose and bicarbonate to predict mortality and guide referral.

An endogenous eczema of sebum-rich areas (scalp, nasolabial folds, post-auricular) producing greasy yellowish scale, associated with the yeast Malassezia.

Infection of the breached skin barrier (often Staphylococcus aureus); in erythroderma it may progress to sepsis, the leading cause of death.

An atypical circulating malignant T lymphocyte with a cerebriform nucleus, sought on the peripheral blood film when cutaneous T-cell lymphoma is suspected as a cause of erythroderma.

The erythrodermic, leukaemic variant of cutaneous T-cell lymphoma, characterised by erythroderma, lymphadenopathy and atypical circulating Sézary cells on the peripheral blood film.

The intermediate form of the spectrum, defined by epidermal detachment of 10–30% of body surface area.

The primary-care bundle of warmth, intravenous fluids and electrolyte correction, emollients, infection control and culprit-drug cessation that keeps an erythrodermic patient alive until specialist care is reached.

A toxin-mediated superficial epidermal split, typically in young children, without true mucosal erosions; an important non-drug differential of TEN.

Eczema of the lower legs and ankles in chronic venous insufficiency, with oedema, haemosiderin pigmentation and sometimes ulceration.

The milder end of the SJS/TEN spectrum, defined by epidermal detachment of less than 10% of body surface area, with mucosal erosions and a positive Nikolsky sign.

A spectrum of epidermal detachment (SJS <10% BSA, overlap 10–30%, TEN >30%) managed in primary care like a major burn with stabilisation and emergency transfer.

The skin's regulation of body temperature through control of blood flow and sweating; its failure in erythroderma causes hypothermia or swinging fever.

A dermatophyte infection whose typical features are masked and modified by inappropriate topical steroid use, leading to atypical, spreading presentations.

A steroid-sparing topical anti-inflammatory (tacrolimus, pimecrolimus) safe for use on the face and skin folds in eczema.

The classification of topical steroids from mild (hydrocortisone 1%) through moderate and potent to very potent (clobetasol propionate 0.05%); potency must be matched to body site, with only mild agents on the face and flexures.

The most severe end of the spectrum, defined by epidermal detachment of more than 30% of body surface area, with widespread skin loss managed like a major burn.

A delayed, T-cell-mediated immune reaction that requires a prior sensitisation phase and is elicited on later re-exposure; the mechanism of allergic contact dermatitis.

Itchy weals from a drug reaction, managed with antihistamines; airway-threatening angioedema is an emergency needing adrenaline and transfer.