6- Dermatology (Emergency: Erythroderma, Eczema herpeticum, Burns, Stings and Bites ) Flashcards
Erythroderma
Background
- Intense and widespread reddening of the skin due to inflammatory skin disease
- Describes erythema that affects >90% of the body surface
- Often precedes skin peeling of scales and layers- known as exfoliative dermatitis
risk factor for erythroderma
males
causes of erythroderma
- Most have pre-existing skin condition e.g. eczema, psoriasis
- Lymphoma and leukaemia
- Drugs e.g. penicillin
- idiopathic
presentation erythdroderma
Presentation
- Preceded by morbilliform (measles like) eruption, dermatitis of plaque psoriasis
- Affects >90% of the skin surface
- Warm to touch
- Itchy
- Pain
- Eyelid swelling
- Scaling
- Palms and soles may develop yellowish diffuse keratoderma
- Nails become dull, ridged and thickened
- Swollen lymph nodes
investigations for erythroderma
- A FBC and peripheral blood film should be examined for abnormal cells.
- Sézary cells (atypical lymphocytes with cerebriform nuclei) are often observed in erythroderma but when they constitute more than 20% of the circulating peripheral blood mononuclear cells they become diagnostic of a form of cutaneous t-cell lymphoma known as the Sézary syndrome
- Histology: multiple biopsies may aid in the diagnosis
which cells are often obsered in blood film in erythroderma
Sézary cells (atypical lymphocytes with cerebriform nuclei) are often observed in erythroderma but when they constitute more than 20% of the circulating peripheral blood mononuclear cells they become diagnostic of a form of cutaneous t-cell lymphoma known as the Sézary syndrome
Complications of erythroderma
- Hypothermia
- Dehydration
- Skin infection
- hypoalbuminemia
managemet of erythroderma
- Discontinue all unnecessary medications
- Monitor fluid balance and body temperature
- Maintain skin moisture with wet wraps, other types of wet dressings, emollients and mild topical steroids
- Prescribe antibiotics for bacterial infection
- Antihistamines may or may not be helpful for the itch.
Burns
Background
- An injury caused by exposure to thermal (heat), electrical, chemical or radiation energy
- A scald is a burn caused by contact with hot liquid or steam
categorisation of burns
complex and non-complex
complex burns
- All electrical and chemical burns
- Any thermal burn affecting critical areas: face, hands, feet, perineam, genitalia, burns crossing joints, circumferential chest burn
- Any thermal burn covering **>15% **of the total body surface area (BSA)
non complex burns
- Any partial-thickness thermal burn covering up to 15% of the total BSA in adults or up to 10% in children that does not affect a critical area
- Deep partial thickness covering <1% of the body
Assessment of burns
Wallace’s rule of Nines estimates an adult’s affected Burn Surface Area (BSA) using multiples of 9 representing different areas of the body.
- Head and neck represent 9%.
- Each lower extremity is 18%.
- Each upper extremity is 9%.
- Anterior and posterior torso are 18% each.
- For scattered or irregular burns, the palmar surface of the person’s hand represents approximately 1%.
- Different calculations are used for children and infants
Complications of burns
- Respiratory distress from smoke inhalation or a circumferential chest burn
- Hypothermia
- Wound infection and sepsis
- TSS
- Cardiac arrhythmias
- Vascular insufficiency
- AKI - Rhabdomyolysis
- Limb loss
- Death
Management of thermal burns
- A to E
- Remove burning process
- Remove non-adherent clothing and jewellery -> do not remove tar stuck to the skin
- Irrigate the burn with cool or tepid running water for 15 to 30 minute (not ice cold as this can cause vasoconstriction and deepen wound)
- Ensure person is keep warm to prevent hypothermia
- After cooling, cover the burn using clinic film
- Do not apply topical creams
- Offer pain relief e.g. paracetamol or ibuprofen, codeine for more severe pain
Management of electrical burns
- Do not approach a person connected to a high voltage source
- If injured by a low-voltage source -> switch off power supply if safe to do so
- Urgent admission to a and e
Management of chemical burns
- Determine causative chemical
- Remove affected clothing
- Irrigate burn with copious amounts of water for an hour
- Do not attempt to neutralise chemicals as additional heat will cause damage
- Admit to a and e
hospital mangement of burns
Hospital
- Clean (debridement) and dress wound
- After 48 hours wound reassed and redressed
- Every 3-5 days until wound is heal
- Assess need for tetanus prophylaxis
- Supportive measures
o Analgesia
o IV hydration
o Good nutrition
o May require intubation if extensive scarring around chest
- Antibiotics if signs or symptoms of infection
insect bites background
Types
- Mosquitos
- Bed bugs
- Fleas
- Horsefly -> lacerate skin (not with mouthparts) and lap pooled blood in the wound
- Tick
Insects inject anticoagulant and vasodilators found in their saliva during feeding to ensure blood flows easily -> hypersensitivity reaction i.e. reaction is worse after the second bite
insect sting background
Types
- Honeybees
- Bumblebees
- Wasps
- Hornets
pathophysiology
- Cause sting by injecting venom from a sac attached to stinger
- Honeybees leave barbed stinger and attached venom sac in the skin after they sting
- Venom contains allergens
o Can cause hypersensitivity reactions
Risk factors for stings and bites
- Occupation
- Increased skin exposure
- Pets e.g. fleas
complications of stings and bites
Complications
- Local skin trauma
- Allergic reaction
- Systemic toxicity
- Transmission of ID e.g. lyme disease
- Bacterial infection e.g. cellulitis
- Psychological distress
Investigations for stings and bites
- Signs of anaphylaxis
- Signs of insect bite or sting
- Infection
Management of stings and bites
- If anaphylaxis -> treat accordingly
- Remove stinger if visible in the skin
- Supportive: oral analgesics, antihistamine, hydrocortisone
- Treat secondary infection with antibiotics
- Clean area
lymes disease
Pathophysiology
- Tick bite
- B. burgdorferi is injected into the skin in tick saliva
- This contains substances that disrupt the immune response at the bite site
- Allows infection establish
- The bacteria multiply in the dermis
- Host inflammatory response causes circular EM lesion
- Spirochaetes spread via the bloodstream.
- The spirochetes may avoid the immune response by a form of molecular mimicry, causing a pathogen-induced auto-immune disease by causing inflammatory substances such as cytokines.
Presentation
* Skin reaction around bite site (erythema migrans)- target lesion
* Regional lymphadenopathy
* Fever
* Headache
Management
- Doxycycline/amoxicillin (14 days, longer if disseminated)
- IV cefotaxime in neurological disease
lymes disease
Pathophysiology
* Tick bite
* B. burgdorferi is injected into the skin in tick saliva
* This contains substances that disrupt the immune response at the bite site
* Allows infection establish
* The bacteria multiply in the dermis
* Host inflammatory response causes circular EM lesion
* Spirochaetes spread via the bloodstream.
* The spirochetes may avoid the immune response by a form of molecular mimicry, causing a pathogen-induced auto-immune disease by causing inflammatory substances such as cytokines.
Presentation
* Skin reaction around bite site (erythema migrans)- target lesion
* Regional lymphadenopathy
* Fever
* Headache
Management
- Doxycycline/amoxicillin (14 days, longer if disseminated)
- IV cefotaxime in neurological disease
Eczema herpeticum
- Widespread herpes infection of eczema lesions
- Typically occurs in children
- Presents with vesicular lesions, typically around the site of a recent dermatitis flare up, although can occur anywhere on the body.
- Patient may become particularly ill, with fever and lymphadenopathy, usually about 5 days after the vesicles appear
- The lesions may later also become infected with staphylococci
- Very rarely, there may be a viraemia, which can be fatal
Management
- Treatment is with aciclovir. A mild or moderate case may be treated with oral aciclovir, whereas more severe cases may require IV aciclovir.
- Antibiotics if bacterial superinfection e.g. impetigo
