Skin and allergy Flashcards
Which surfaces does eczema appear on usually?
Flexor surfaces and face and neck
What are periods of uncontrolled eczema called?
Flares
Give a brief overview pathophysiology of eczema
Break in skin barrier -> entrance for irritants, microbes and allergens -> immune response -> inflammation and other symptoms
What are management ideas for mild eczema?
Emollients Soap substitutes Avoid activities breaking down skin barrier Destress Avoid irritants
How do you manage eczema flares?
Topical steroids
Thicker emollients
“Wet wraps”
Treat complications
(rare) - IV abx or oral steroids for severe flares
(specialist) zinc bandanges, topical tacrolimus, phototherapy, immunosuppressants (methotrexate, aziathoprine)
Side effects of steroid use in eczema?
Thinning of skin
Telangiectasia
Systemic absorption of steroid
Most common bacterial infection in eczema?
How to treat?
Staph aureus
Oral flucloxacillin
Eczema herpeticum is caused by which virus(es)?
HSV-1 or VZV
Give a typical presentation of eczema herpeticum
Widespread, painful, vesicular rash
Systemic symptoms - fever, lethargy, irritability, reduced oral intake
Swollen lymph nodes
How do you confirm a diagnosis of eczema herpeticum?
Viral swabs of the vesicles
Gold standard drug to treat eczema herpeticum
Oral aciclovir
Severe = IV aciclovir
In which group of children is eczema herpeticum more dangerous?
Immunocompromised children
Can get bacterial superinfection (more severe illess) which needs abx
What is the hallmark pathology of Stevens-Johnson Syndrome?
Epidermal necrosis
Main difference between Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis?
SJS affects <10% of body surface area, TEN affects >10%
Give medication causes of Stevens-Johnson Syndrome
Anti-epileptics
Antibiotics
Allopurinol
NSAIDs
Give infection causes of Stevens-Johnson Syndrome
Herpes simplex
Mycoplasma pneumonia
CMV
HIV
What is a common presentation of Stevens-Johnson Syndrome?
Non-specific symptoms (cough, fever, sore mouth/eyes/skin)
Followed by purple/red rash
Followed by blistering of skin, peeling away - leaving raw tissue underneath
Lips and mucus membranes, eyes inflamed and ulcerated
Also affects urinary tract, lungs and internal organs
What management is appropriate for Stevens-Johnson Syndrome?
a) admit where?
b) conservative care
c) what drugs?
a) Admit to derm/burns unit
b) Supportive care - nutrition, antiseptics, analgesia, opthalmology.
c) Tx: steroids, immunoglobulins and immunosuppressants
Give 3 complications of Stevens-Johnson Syndrome
Secondary infection
Permanent skin damage
Visual complications
What hypersensitivity type is allergic rhinitis?
IgE-mediated Type 1 hypersensitivity
Allergic rhinitis can occur at different times of the year: on a ______ level, a _______, level and also be associated with _______ (e.g. work/school)
Seasonal
Perennial
Occupational
Runny, blocked and itchy nose, sneezing and itching, red swollen eyes is associated with?
Allergic rhinitis
Investigations for allergic rhinitis?
History
Skin prick testing (? allergies)
Management of allergic rhinitis
a) conservative
b) pharmacological
a) Avoid trigger
b) Oral antihistamines - non-sedating (cetirizine) and sedating (chlorphenamine)
Nasal corticosteroids sprays (fluticasone)
Nasal antihistamines
What is another name for urticaria?
What is urticaria?
Hives
Small itchy lumps on skin
Sometimes patchy, red rashes on skin
What chemical is responsible for urticaria and which cells release it?
Histamine - released by mast cells
How do acute urticaria and chronic idiopathic urticaria differ in terms of pathology?
Acute - allergic reaction
Chronic - autoimmune reaction
What are potential causes of acute urticaria?
Allergies to food, meds, pets Chemicals, latex contact Medications Viral infections Insect bites Dermatographism (skin rubbing)
What triggers can happen with chronic urticaria?
Sunlight Temp change Exercise Strong emotions Hot/cold weather Pressure
Autoimmune - SLE
What is the gold standard treatment for urticaria?
Antihistamines - Fexofenadine
Short course of oral steroids only for severe flares
(Specialist) - Anti-leukotrienes (montelukast), Omalizumab (anti-IgE), Cyclosporin
What type of hypersensitivity reaction is anaphylaxis?
Type 1 IgE mediated
What key feature separates anaphylaxis from non-anaphylactic allergic reaction?
Compromised A B C
What acute symptoms can appear with anaphylaxis?
Urticaria Itching Angiooedema (swelling lips/eyes) Abdo pain SOB Wheeze Stridor (larynx is swollen) Tachycardia Lightheaded Collapse
What is the ABCDE management approach to anaphylaxis?
A – Airway: Secure the airway
B – Breathing: Provide oxygen if required. Salbutamol can help with wheezing.
C – Circulation: Provide an IV bolus of fluids
D – Disability: Lie the patient flat to improve cerebral perfusion
E – Exposure: Look for flushing, urticaria and angio-oedema
What are the 3 medications given to anaphylactic patients?
- IM adrenaline (repeat after 5mins as needed)
- Antihistamines (cetirizine)
- Steroids (IV hydrocortisone)
What can happen after the initial anaphylaxis?
Rebound anaphylaxis
What gold standard lab test can confirm anaphylaxis within 6 hours of the event?
Serum mast cell tryptase
What is crusted dry flaky scalp on infants caused by?
Seborrhoeic dermatitis due to Malassezia yeast
What drug can be used to treat seborrhoeic dermatitis?
Antifugals e.g. ketoconazole shampoo or miconazole cream
Localised areas can be treated with topical steroids (hydrocortisone)
List the 5 ringworm pathologies
Tinea capitis Tinea corporis Tinea cruris Tinea pedis Oncychomycosis (nail)
What is the most common type of fungus that causes ringworm?
Trichophyton
What is the risk of fungal toenail infections?
Infection can spread to the skin
Treatment for ringworm
Antifungals - creams/shampoos, oral anti-fungals
Conservative treatment such as loose clothing, good hygiene
Clinical features of ringworm infection
Itchy rash that is:
Erythematous, scaly and well-demarcated
What is nappy rash caused by?
Contact dermatitis due to friction between skin and nappy +/- urine/faeces
Sometimes staph/strep/candida can complicate
Give some risk factors for nappy rash
Delayed nappy changing Irritant soaps Vigorous cleaning Poorly absorbent nappies Diarrhoea Pre-term infants
How do candida and nappy rash differ?
Candida rash extends into skin creases Larger red macules Well-demarcated scaly border Circular pattern to rash, going outwards Satellite lesions Oral thrush (white tongue coating)
How can nappy rash be managed?
Switch to high absorbing nappies Change nappy often and clean skin Water/alcohol-free cleaning Dry nappy area before replacing Maximise time free of wearing nappy
Treat complications - e.g. antifungal miconazole for candida or antibiotic flucloxacillin for staph
What organism causes scabies?
Mites
What is the classic location of scabies rash?
Between finger webs
What does scabies rash look like?
Little red, itchy spots on skin
What is the gold standard treatment for scabies?
Permethrin cream
(if difficult to treat, use oral ivermectin single dose)
Treat all household members even if asymptomatic
Wash and hoover and clean all clothes
What is Norweigian scabies?
Crusted scabies - occurs in immunocompromised patients
Admit for treatment with oral ivermectin and isolated nursing!! (highly contagious!)
Treatment of choice for headlice?
Dimeticone 4% lotion applied to hair
Fine combs
(Bug buster kit)
Give differential diagnoses for NON-BLANCHING rashes (8 total)
- Bacterial sepsis
- HSP
- ITP
- Acute leukaemia
- HUS
- Mechanical
- Traumatic
- Viral illness
Investigations for NON-BLANCHING RASHES
FBC (HUS/Leukaemia/ITP/Sepsis)
U&Es (HUS/HSP)
CRP
ESR (HSP/infection)
Coag screen (clotting abnormalities)
Blood culture (sepsis)
Meningococcal PCR
LP (meningitis/encephalitis)
BP check (HSP, HUS. HypoTN in septic shock)
Urine dipstick (proteinuria/haematuria with HSP or HUS)
What 2 chronic conditions can erythema nodosum indicate?
IBD
Sarcoidosis
What conditions can erythema nodosum be caused by usually?
Strep throat infections Gastroenteritis Mycoplasma pneumonia TB Pregnancy Meds (OCP and NSAIDs)
Which investigations to carry out for erythema nodosum and find the underlying cause?
ESR/CRP
Throat swab (?strep)
CXR (mycoplasma, TB, sarcoidosis, lymphoma)
Stool MC&S (campylobacter, salmonella)
Faecal calprotectin (IBD)
How is erythema nodosum managed?
Conservatively - rest and analgesia
Steroids for inflammation if needed
Self-resolving in 6 weeks usually
What is a typical presentation of erythema nodosum?
Red, inflammed subcut nodules on both shins
Painful, tender
Bruises can appear too later over nodules
What causes Staphylococcal Scalded Skin Syndrome?
S. aureus producing epidermolytic toxins
What age is Staphylococcal Scalded Skin Syndrome most common in?
Children under 5 years
older children usually have developed immunity to it
What is Nikolsky sign?
Positive sign seen in SSSS
Gentle rubbing of skin causes it to rub away.
What are important features of Staphylococcal Scalded Skin Syndrome?
Erythema –> Bullae blisters –> Burst —> Expose skin below
Can progress to fever, irritability, lethargy, dehydration.
Dangerous: sepsis and death
How is Staphylococcal Scalded Skin Syndrome treated?
Admit and start IV antibiotics
Fluid and electrolyte balance (due to dehydration)
What are the 4 types of psorasis?
- Plaque (mostly in adults)
- Guttate - (strep infection, mostly in children, trunk and limbs)
- Pustular (rare, severe)
- Erythrodermic (rare, severe)
Auspitz sign, Koebner phenomenon and residual pigmentation of skin are seen in what condition?
Psorasis
Auspitz sign = small points of bleeding when plaque scraped of
Koeber phenomenon = psoriatic lesions to skin affected by trauma)
Residual pigmentation left on skin after resolution of psoriasis
Which surfaces does psoriasis usually occur on?
Extensor surfaces + scalp
What are pharmcological management options for psoriasis?
Steroids
Vit D analogues
Dithranol
Phototherapy (if extensive)
What non-skin issues can be seen with psoriasis?
Nail psoriasis
Psoriatic arthritis (usually in middle age)
Psychosocial issues
