Dermatological emergencies

Question 1

What is urticaria?

Answer 1

Urticaria is characterised by weals (hives) or angioedema (swellings, in 10%) or both (in 40%). There are several types of urticaria.

Question 2

What is angioedema?

Answer 2

Angioedema is deeper swelling within the skin or mucous membranes and can be skin-coloured or red. It resolves within 72 hours. Angioedema may be itchy or painful but is often asymptomatic.

Question 3

What is acute urticaria?

Answer 3

Acute urticaria is urticaria, with or without angioedema, that is present for less than 6 weeks. It is often gone within hours to days.

Question 4

Who is especially prone to developing urticaria?

Answer 4

Atopic individuals

Question 5

What are the clinical features of acute urticaria?

Answer 5

Urticarial weals can be a few millimetres or several centimetres in diameter, coloured white or red, with or without a red flare. Each weal may last a few minutes or several hours and may change shape. Weals may be round, or form rings, a map-like pattern, targetoid lesions, or giant patches. Acute urticaria can affect any site of the body and tends to be distributed widely. Angioedema is more often localised. It commonly affects the face (especially eyelids and perioral sites), hands, feet and genitalia. It may involve tongue, uvula, soft palate, larynx. Serum sickness due to blood transfusion and serum sickness-like reactions due to certain drugs cause acute urticaria leaving bruises, fever, swollen lymph glands, joint pain and swelling.

Question 6

What causes acute urticaria? (think biochemistry)

Answer 6

Weals are due to release of chemical mediators from tissue mast cells and circulating basophils. These chemical mediators include histamine, platelet-activating factor and cytokines. The mediators activate sensory nerves and cause dilation of blood vessels and leakage of fluid into surrounding tissues. Bradykinin release causes angioedema.

Question 7

Give 5 causes of acute urticaria? (think diseases etc)

Answer 7

1. Acute viral infection — an upper respiratory infection, viral hepatitis, infectious mononucleosis
2. Acute bacterial infection — a dental abscess, sinusitis, mycoplasma
3. Food allergy (IgE mediated) — usually milk, egg, peanut, shellfish
4. Drug allergy (IgE mediated) — often an antibiotic
5. Drug pseudoallergy — aspirin, nonselective nonsteroidal anti-inflammatory drugs, opiates, radiocontrast media; these cause urticaria without immune activation
6. Vaccination
7. Bee or wasp stings
8. Widespread reaction following localised contact urticaria — rubber latex

Question 8

What will a biopsy of urticaria show?

Answer 8

Biopsy of urticaria can be non-specific and difficult to interpret. The pathology shows oedema in the dermis and dilated blood vessels, with a variable mixed inflammatory infiltrate. Vessel-wall damage indicates urticarial vasculitis.

Question 9

What 3 investigations can be ordered in the case of acute urticaria if drug or food allergies are suspected?

Answer 9

Skin prick tests and radioallergosorbent tests (RAST) or CAP fluoroimmunoassay may be requested if a drug or food allergy is suspected in acute urticaria.

Question 10

What are the 2 key patient characteristics for diagnosing acute urticaria?

Answer 10

Acute urticaria is diagnosed in people with

• a short history of weals that last less than 24 hours,
• with or without angioedema.

Question 11

What is the management of acute urticaria?

Answer 11

The main treatment for acute urticaria in adults and in children is with an oral second-generation antihistamine chosen from the list below. If the standard dose (eg 10 mg for cetirizine) is not effective, the dose can be increased fourfold (eg 40 mg cetirizine daily). They are best taken continuously rather than on demand. They are stopped when the acute urticaria has settled down. There is not thought to be any benefit from adding a second antihistamine.

1. Cetirizine
2. Loratadine

Question 12

If non-sedating histamines aren’t effective, what shuld be tried next?

Answer 12

If non-sedating antihistamines are not effective, a 4 to 5-day course of oral prednisone (prednisolone) may be warranted in severe acute urticaria, particularly if there is angioedema. Systemic steroids do not speed up the resolution of symptoms.

Question 13

What are Stevens-Johnson syndrome and Toxic epidermal necrolysis?

Answer 13

Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are now believed to be variants of the same condition, distinct from erythema multiforme. SJS/TEN is a rare, acute, serious, and potentially fatal skin reaction in which there are sheet-like skin and mucosal loss. Using current definitions, it is nearly always caused by medications.

Question 14

Which group is 100x more likely to develop SJS/TEN?

Answer 14

HIV positive patients

Question 15

Give 5 drug classess that most commonly causes SJS?TEN?

Answer 15

1. Sulfonamides: cotrimoxazole
2. Beta-lactam: penicillins, cephalosporins
3. Anti-convulsants: lamotrigine, carbamazepine, phenytoin, phenobarbitone
4. Allopurinol
5. Paracetamol/acetaminophen
6. Nevirapine (non-nucleoside reverse transcriptase inhibitor)
7. Nonsteroidal anti-inflammatory drugs (NSAIDs) (oxicam type mainly).

Question 16

What are the important early biochemical markers of SJS/TEN?

Answer 16

Drug-specific CD8+ cytotoxic lymphocytes can be detected in the early blister fluid. They have some natural killer cell activity and can probably kill keratinocytes by direct contact. Cytokines implicated include perforin/granzyme, granulysin, Fas-L and tumour necrosis factor alpha (TNFα).

Question 17

What is the time onset of SJS/TEN in:

• Antibiotics?
• Anticonvulsants?
• Most other drugs?

Answer 17

SJS/TEN usually develops within the first week of antibiotic therapy but up to 2 months after starting an anticonvulsant. For most drugs, the onset is within a few days up to 1 month.

Question 18

What is the earliest sign of developing SJS/TEN?

Answer 18

Prodromal symptoms

• Fever > 39 C
• Sore throat, difficulty swallowing
• Runny nose and cough
• Sore red eyes, conjunctivitis
• General aches and pains

Question 19

What is the initial presentation of the rash in SJS/TEN? When is its maximum extent reached? Where does it rarely effect?

Answer 19

There is then an abrupt onset of a tender/painful red skin rash starting on the trunk and extending rapidly over hours to days onto the face and limbs (but rarely affecting the scalp, palms or soles). The maximum extent is usually reached by four days.

Question 20

Nikolsky sign is positive in SJS/TEN. What is Nikolsky’s sign?

Answer 20

Nikolsky’s sign is positive when slight rubbing of the skin results in exfoliation of the skin’s outermost layer

Question 21

What 4 configurations might the skin lesions in SJS/TEN take?

Answer 21

1. Macules — flat, red and diffuse (measles-like spots) or purple (purpuric) spots
2. Diffuse erythema
3. Targetoid — as in erythema multiforme
4. Blisters — flaccid (ie, not tense).

Question 22

Involvement of what surface is often prominent and severe?

Answer 22

Mucosal surfaces

Question 23

Give 5 potentially fatal features of early SJS/TEN?

Answer 23

1. Dehydration and acute malnutrition
2. Infection of skin, mucous membranes, lungs (pneumonia), septicaemia (blood poisoning)
3. Acute respiratory distress syndrome
4. Gastrointestinal ulceration, perforation and intussusception
5. Shock and multiple organ failure including kidney failure
6. Thromboembolism and disseminated intravascular coagulopathy.

Question 24

How is SJS/TEN diagnosed?

What are the defining features which allow you to categorise into: SJS, overlap SJS/TEN, TEN with spots, TEN without spots?

Answer 24

SJS/TEN is suspected clinically and classified based on the skin surface area detached at maximum extent.

SJS

• Skin detachment < 10% of body surface area (BSA)
• Widespread erythematous or purpuric macules or flat atypical targets

Overlap SJS/TEN

• Detachment between 10% and 30% of BSA
• Widespread purpuric macules or flat atypical targets

TEN with spots

• Detachment > 30% of BSA
• Widespread purpuric macules or flat atypical targets

TEN without spots

• Detachment of > 10% of BSA
• Large epidermal sheets and no purpuric macules

Question 25

What test can be predictive of SJS/TEN development?

Answer 25

Serum granulysin

Question 26

What is the importance of skin biopsy in SJS/TEN? What will be seen on skin biopsy of an SJS/TEN patient?

Answer 26

* Skin biopsy is usually required to confirm the clinical diagnosis and to exclude staphylococcal scalded skin syndrome (SSSS) and other generalised rashes with blisters. * The histopathology shows keratinocyte necrosis (death of individual skin cells), full thickness epidermal/epithelial necrosis (death of an entire layer of skin), minimal inflammation (very mild lymphocytic infiltrate of the superficial dermis). The direct immunofluorescence test on the skin biopsy is negative, indicating the disease is not due to deposition of antibodies in the skin.

Question 27

What other investigations should be conducted in suspected/confirmed SJS/TEN? Not to diagnose but to assess impact

Answer 27

1. Anaemia occurs in virtually all cases (reduced haemoglobin). 2. Leucopenia (reduced white cells), especially lymphopenia (reduced lymphocytes) is very common (90%). 3. Neutropenia (reduced neutrophils), if present, is a bad prognostic sign. 4. Eosinophilia (raised eosinophil count) and atypical lymphocytosis (odd-looking lymphocytes) do not occur. 5. Mildly raised liver enzymes are common (30%), and approximately 10% develop overt hepatitis. 6. Mild proteinuria (protein leaking into the urine) occurs in about 50%. Some changes in kidney function occur in the majority.

Question 28

What score is used to assess severity of SJS/TEN?

Answer 28

SCORTEN is an illness severity score that has been developed to predict mortality in SJS and TEN cases. One point is scored for each of the seven criteria present at the time of admission. The SCORTEN criteria are: * Age \> 40 years * Presence of malignancy (cancer) * Heart rate \> 120 * Initial percentage of epidermal detachment \> 10% * Serum urea level \> 10 mmol/L * Serum glucose level \> 14 mmol/L * Serum bicarbonate level \< 20 mmol/L.

Question 29

What are the 7 key tenets of care of a patient with SJS/TEN?

Answer 29

1. Cessation of suspected causative drug(s) 2. Consider fluidised air bed 3. Nutritional and fluid replacement (crystalloid) by intravenous and nasogastric routes 4. Temperature maintenance 5. Pain relief 6. Skin care 7. Mucosa care

Question 30

WHat topical antiseptics can be used in SJS/TEN?

Answer 30

Topical antiseptics can be used (eg, silver nitrate, chlorhexidine [but not silver sulfadiazine as it is a sulfa drug])

Question 31

Give 7 long term sequelae of SJS/TEN?

Answer 31

1. Pigment change — a patchwork of increased and decreased pigmentation 2. Skin scarring, especially at sites of pressure or infection 3. Loss of nails with permanent scarring (pterygium) and failure to regrow 4. Scarred genitalia — phimosis (constricted foreskin which cannot retract) and vaginal adhesions (occluded vagina) 5. Joint contractures 6. Lung disease — bronchiolitis, bronchiectasis, obstructive disorders. 7. Eye disorders

Question 32

What iserythroserma?

Answer 32

Erythroderma is the term used to describe intense and usually widespread reddening of the skin due to inflammatory skin disease. It often precedes or is associated with exfoliation (skin peeling off in scales or layers), when it may also be known as exfoliative dermatitis (ED). Idiopathic erythroderma is sometimes called the ‘red man syndrome’.

Question 33

What are the 4 most common conditions to lead to erythroderma?

Answer 33

1. Drug eruption — with numerous diverse drugs implicated (list of drugs) 2. Dermatitis especially atopic dermatitis 3. Psoriasis, especially after the withdrawal of systemic steroids or other treatment 4. Pityriasis rubra pilaris

Question 34

Give 4 systemic disease which can lead to erythroderma?

Answer 34

1. Haematological malignancies, such as lymphoma and leukaemia 2. Internal malignancies, such as carcinoma of rectum, lung, fallopian tubes, colon, prostate (paraneoplastic erythroderma) 3. Graft-versus-host disease 4. HIV infection.

Question 35

What are the clinical features of onset in erythroderma?

Answer 35

Erythroderma is often preceded by a morbilliform (measles-like) eruption, dermatitis, or plaque psoriasis. Generalised erythema can develop quite rapidly in acute erythroderma, or more gradually over weeks to months in chronic erythroderma.

Question 36

The following clues indicate what causes of erythroderma: * Serous ooze? * Persistence of circumscribed scaly plaques on elbows and knees? * Islands of spraing, follicular prominence, orange hue to kertaoderma? * Subungual hyperkeratosis?

Answer 36

* Serous ooze, resulting in clothes and dressings sticking to the skin and an unpleasant smell, is characteristic of atopic erythroderma. * Persistence of circumscribed scaly plaques in certain sites such as elbows and knees suggests psoriasis. * Islands of sparing, follicular prominence, orange-hue to keratoderma are typical of pityriasis rubra pilaris. * Subungual hyperkeratosis, crusting on palms and soles, and burrows are indicative of crusted scabies.

Question 37

Give 5 general measures for treatment of erythroderma

Answer 37

1. Discontinue all unnecessary medications 2. Monitor fluid balance and body temperature 3. Maintain skin moisture with wet wraps, other types of wet dressings, emollients and mild topical steroids 4. Prescribe antibiotics for bacterial infection 5. Antihistamines may or may not be helpful for the itch.

Question 38

What is eczema herpeticum?

Answer 38

Eczema herpeticum is a disseminated viral infection characterised by fever and clusters of itchy blisters or punched-out erosions. It is most often seen as a complication of atopic dermatitis/eczema.

Question 39

What is the most common cause of eczema herpeticum? Is eczema herpeticum more common on first exposure or subsequent exposures to the main cause? Following exposure, how long does it take for eczema herpeticum to show?

Answer 39

* Most cases of eczema herpeticum are due to Herpes simplex type 1 or 2. * Eczema herpeticum usually arises during a first episode of infection with Herpes simplex (primary herpes). * Signs appear 5–12 days after contact with an infected individual, who may or may not have visible cold sores.

Question 40

How does eczema herpeticum start? Where does it most commonly affect? Over what period of time do new patches form and spread?

Answer 40

* Eczema herpeticum starts with clusters of itchy and painful blisters. * It may affect any site but is most often seen on face and neck. Blisters can occur in normal skin or sites actively or previously affected by atopic dermatitis or another skin disease. * New patches form and spread over 7–10 days and may rarely be widely disseminated throughout the body.

Question 41

Are blisters in eczema herpeticum pleomorphic or monomorphic?

Answer 41

Monomorphic

Question 42

What features do now exzema herpeticum blisters often have?

Answer 42

Central dimples

Question 43

What is this an example of?

Answer 43

Eczema herpeticum

Question 44

When can eczema herpeticum be diagnosed clinically?

Answer 44

Eczema herpeticum can be diagnosed clinically when a patient with known atopic dermatitis presents with an acute eruption of painful, monomorphic clustered vesicles associated with fever and malaise. Viral infection can be confirmed by viral swabs taken by scraping the base of a fresh blister.

Question 45

Give 4 lab tests which can aid in the diagnosis of eczema herpeticum

Answer 45

* Viral culture * Direct fluorescent antibody stain * PCR (Polymerase Chain Reaction) sequencing * Tzank smear showing epithelial multinucleated giant cells and acantholysis (cell separation)

Question 46

Why is it important to send bacterial swabs even in eczema herpeticum?

Answer 46

Bacterial swabs should also be taken for microscopy and culture as eczema herpeticum may resemble impetigo and it can be complicated by secondary bacterial infection.

Question 47

What are the 3 key tenets of management of eczema herpeticum?

Answer 47

* Oral aciclovir 400–800 mg 5 times daily, or, if available, valaciclovir 1 g twice daily, for 10–14 days or until lesions heal. Intravenous aciclovir is prescribed if the patient is too sick to take tablets, or if the infection is deteriorating despite treatment. * Secondary bacterial skin infection is treated with systemic antibiotics. * Topical steroids are not generally recommended but may be necessary to treat active atopic dermatitis.