Dermatology Flashcards
Why do hives occur ?
Due to the release of histamine from mast cells due to exposure to an allergen or idiopathically
What are the clinical features of urticaria (Hives) ?
- Small itchy bumps
- Can be acute or chronic
- Can be specific or widespread
- Skin may be flushed or erythematous
What are some causes of acute urticaria ?
- Allergies
- Contact with allergen
- Medications
- Infection or insect bites
What are some causes of chronic urticaria ?
Chronic idiopathic – Recurrent episodes without a clear cause
Chronic inducable – Sunlight, temp exposure, emotions, pressure, weather
Autoimmune – Associated with an underlying condition like SLE.
What is the main treatment for urticaria ?
Antihistamines
Oral steroids can be given in severe cases
What is the first line of treatment for chronic urticaria ?
Fexofenadine
What is nectrotising fasciitis ?
Infection involving the deep soft tissue compartments. Organisms migrate from subcutaneous tissue along the fascial planes
What are the main causative organisms of NF ?
Group A strep
Gram neg organisms acquired from seawater
Fungal infection like candida
Many cases are polymicrobial (AEROBIC AND ANAEROBIC)
What are some of the clinical features of NF ?
Pain out of proportion to clinical findings
Skin discoloration and skin blistering
Fever and malaise
Fever and hypotension
Tachycardia
Local pain, swelling and erythema
Poor margins and pain extending beyond the margins
Crepitus in palpation
Offensive discharge
Oedema
Bullae (blisters)
What are some of the Rf for NF ?
Skin injury
Impaired immunity like malignancy, immunosuppression, diabetes, CKD ect
IV drug use
On investigation, what will present in NF ?
Raised WCC unless immunocompromised
Hyponatremia
Raised CRP and CK
Raised lactate
BC, wound swabs and debrided tissue gram stain and culture
Coag screen and group and save
A CT can be useful but should not delay treatment
What is the bedside finger test for nectrotising fascitis ?
Small incision is made to the fascia under LA
Tissue is probed with sterile glove finger
Absence of bleeding, purulent pus and lack of tissue resistance
How is NF medically managed ?
- A-E assessment
- BS antibiotics as soon as possible
How is NF surgically managed ?
Urgent surgical debridement and wound monitor. May need further surgery until the infection is controlled.
What is cellulitis ?
Infection of the skin and the soft tissues underneath. Patients often have a breach in the skin barrier like trauma, eczema, fungal nail infections or ulcers
Most common causative organisms of cellulitis ?
Staphylococcus aureus
Group A strep (Pyrogens)
Group C step (dysgalactiae)
MRSA
What are the clinical features of cellulitis ?
Erythema
Warm or hot to touch
Tense and thickened
Odema
Bullae
What infective organism does a yellow crust indicate ?
staphylococcus aureus
What classification is used to classify cellulitis ?
THE ERON classification is used to classify cellulitis
Class 1 – no systemic toxicity or comorbidity
Class 2 – systemic toxicity or comorbidity
Class 3 – significant systemic toxicity or significant comorbidity
Class 4 – sepsis or life-threatening
What is first line of treatment for cellulitis ?
Flucloxacillin is first line in cellulitis and can be given oral or IV (IV in class ¾ or co-morbidities)
What are some of the other antibiotic options available to treat cellulitis ?
Clarithromycin, clindamycin and Co-amoxiclav can also be used.
What medications can trigger psoriasis ?
BB, Antimalarials, Lithium and NSAIDS
What are some of the other triggers for psoriasis ?
Positive family history in 1/3 of patients
Can be triggered by – Stress, trauma, infection (Strep and HIV), alcohol, smoking, weather
Withdrawal of steroids.
What are the clinical features of psoriasis ?
Dry, flaky, scaly skin
Erythematous lesions in raised and rough plaques
Extensor surfaces like the elbows, Knees and scalp.
Symmetrical distribution.
What are the nail changes associated with Psoriasis ?
Nail pitting
Onycholysis (Separation of nail plate from nail bed)
Subungual hyperkeratosis (Thickening of the nailbed)
What signs are associated with psoriasis ( Not on the nailbed)?
Auspitz sign – Small points of bleeding when plaques are scraped off
Koebner phenomenon – Psoriatic lesions to areas of skin affected by trauma.
Residual pigmentation of the skin after lesions evolve.
Describe plaque psoriasis ?
Thick erythematous plaques with sliver scales, common on the extensor surfaces and scalp. Most common in adults
What is guttate psoriasis ?
Most commonly occurs in children. Small raised papules across the trunk and the limbs. These can be erythematous and scaly and can transform into plaque psoriasis. Often triggered by a streptococcal throat infections/stress/medication. Spontaneously resolves within 3-4 months.
What is a common infective cause of guttae psoriasis ?
Streptococcus throat infection
What is pustular psoriasis ?
– Rare and severe. Pustules form under areas of erythematous skin. Patients are systemically unwell and a medical emergency. Should be admitted to hospital.
What should all patients with psoriasis do in terms of management ?
All patients should manage RF and use emollient to reduce scale and itch
What are the topical treatments for psoriasis (from first line to final line)?
Corticosteroids target inflammation and vitamin D analogues reduce keratinocyte proliferation
1- Potent topical corticosteroid OD (Betnovate) + topical vitamin D OD (eg Dovonex/Calcipotriol) applied at different times
2 – Stop corticosteroid and use topical Vit D TD
3 - Stop the topical vitamin D, apply potent topical corticosteroid twice daily
Dithranol + tar are alternatives
What phototherapy is offered in psoriasis ?
Narrow band UVB
What are some systemic treatments of psoriasis ?
methotrexate ( Can cause panty cytopenia, hepatoxicity and pneumonitis), then ciclosporin ( 5 Hs), then acitretin ( Tetarogenic)
What are the side effects of methotrexate ?
Pulmonary and liver fibrosis
Myelosupression
Mucositis
Tetarogenic
What are the side effects of ciclosporin (Immunosuppressant - It is used to prevent rejection of new organs following a transplant operation, rheumatoid arthritis, severe dermatitis and psoriasis or nephrotic syndrome)
5 HS
What is a key risk of acitretin (used in severe psoriasis) ?
Used in severe psoriasis - Teratogenic