Derm Flashcards
What is impetigo
Superficial bacterial skin infection usually caused by either Staphylcoccus aureus or Streptococcus pyogenes
Who is impetigo common in
common in children, particularly during warm weather
Where do impetigo lesions tend to occur
The infection can develop anywhere on the body but lesions tend to occur on the face, flexures and limbs not covered by clothing.
How is impetigo spread
Spread is by direct contact with discharges from the scabs of an infected person.
The bacteria invade the skin through minor abrasions and then spread to other sites by scratching.
Infection is spread mainly by the hands, but indirect spread via toys, clothing, equipment and the environment may occur.
The incubation period is between 4 to 10 days.
Appearance of impetigo
‘golden’, crusted skin lesions typically found around the mouth
Mx of limited localised impetigo
Hydrogen peroxide 1% cream
Topical antibiotic creams(fusidic acid)
What should be used in localised impetigo if there is resistance to fusidic acid
Topical mupirocin
Mx of extensive impetigo
Oral flucloxacillin
Oral erythromycin if penicillin-allergic
Advice regarding school exclusion for patients with impetigo
Children should be excluded from school until the lesions are crusted and healed or 48 hours after commencing antibiotic
Areas typically affected by rosacea
Nose, cheeks and forehead
Appearance of rosacea
Flushing is often first symptom
Telangiectasia are common
Later develops into persistent erythema with papules and pustules
rhinophyma
ocular involvement: blepharitis
sunlight may exacerbate symptoms/
General advice for rosacea
Reduce common triggers that cause facial flushing.
Avoid oil-based facial creams. Use water-based make-up.
Never apply a topical steroid to the rosacea as although short-term improvement may be observed (vasoconstriction and anti-inflammatory effect), it makes the rosacea more severe over the next weeks (possibly by increased production of nitric oxide).
Protect yourself from the sun
Keep your face cool to reduce flushing: minimise your exposure to hot or spicy foods, alcohol, hot showers, hot baths, and warm rooms.
Some people find they can reduce facial redness for short periods by holding an ice block in their mouth, between the gum and cheek
Management of mild symptoms of rosacea
Topical metronidazole
Topical brimonidine gel may be considered for patients with predominant flushing but limited telangiectasia
Management of severe rosacea
Systemic antibiotics(oxytetracycline)
What is shingles
Shingles is an acute, unilateral, painful blistering rash caused by reactivation of the Varicella Zoster Virus (VZV) in the dorsal root ganglion or cranial nerve ganglia
Triggers for shingles
Emotional stress Immunosuppression Chemotherapy High dose steroid therapy Recent illness or surgery Skin injury Sunburn Trauma)
What type of nerves are affected in shingles
As the VZV affects the dorsal and/or cranial nerve ganglia, the sensory nerves are what are affected in the course of the disease, hence the characteristic single dermatome distribution
Phases of shingles
prodromal phase, the infectious rash, and the resolution phase
Rash features in shingles
Usually affecting a single dermatome in a band-like distribution
Unilateral, rarely crossing the midline
Initially is erythematous and macular in nature
Progression to erythematous papules, and eventually vesicles or bullae by day 7(lasts 7-10 days)
Vesicles become pustular or haemorrhagic near the end of this phase, right before crusting over
Supportive mx of shingles
Mild analgesia Amitrptyline/duloxetine/gabapentin in moderate-severe pain Calamine lotion Topical capsaicin Cool compress
When do NICE recommend anti-virals in shingles
Within 72 hrs of rash if:
Immunocompromised patients
Non-truncal rash involvement (e.g. affecting face, neck, limbs, perineum)
Moderate-severe pain or rash
age>50
How long after a shingles rash onset can antivirals still be considered an option
one week after rash onset
Use of corticosteroids in shingles
If a patient is on anti-viral treatment –> oral corticosteroids
Used in the first 2 weeks following rash onset
This should only be used in conjunction with anti-viral treatment, and in immunocompetent adults with localised shingles if the pain is severe
Most common complication of shingles
Post-herpetic neuralgia
When should patients with shingles be referred/admitted
Herpes zoster ophthalmicus or eye involvement
Immunocompromised people
Risk factors for shingles
increasing age
HIV: strong risk factor, 15 times more common
other immunosuppressive conditions (e.g. steroids, chemotherapy)
Most common form of skin cancer
BCC
Subtypes of BCC
Sub types include nodular, morphoeic, superficial and pigmented.
Growth of BCC
Typically slow growing with low metastatic potential
Mx of BCC
Standard surgical excision, topical chemotherapy and radiotherapy are all successful.
As a minimum a diagnostic punch biopsy should be taken if treatment other than standard surgical excision is planned.
Most common type of BCC
Nodular
Appearance of BCC
sun-exposed sites, especially the head and neck account for the majority of lesions
initially a pearly, flesh-coloured papule with telangiectasia
may later ulcerate leaving a central ‘crater’
Mx options for BCC
Surgical removal Curettage Cryotherapy Topical creams Radiotherapy
Topical cream options for BCC
Imiquimod
Fluorouracil
Risk factors for SCC
Sunlight exposure/UVA Actinic keratoses Immunosuppression(organ transplant/HIV) Smoking Long-standing leg ulcers Genetic conditions
Mx of SCC
Surgical excision - wide local excision
Mohs micrographic surgery in high-risk patients and in cosmetically important sites
What is Bowen’s disease
Squamous cell carcinoma in situ - erythematous scaling patch or elevated plaque arising on sun-exposed skin in an elderly patient
What is a pyogenic granuloma
These present as friable overgrowths of granulation at sites of minor trauma.
They may be ulcerated and bleeding on contact is common.
Mx of pyogenic granuloma
They may be treated with curettage and cautery, formal excision may be used if there is diagnostic doubt.
Major criteria for diagnosis of malignant melanoma
Change in size
Change in shape
Change in colour
Mx of malignant melanoma
Excision biopsy
Further treatments include sentinel lymph node mapping, isolated limb perfusion and block dissection of regional lymph node groups
How are margins of excision determined in melanoma excision
Linked to breslow thickness
What is dermatitis herpetiformis
Chronic itchy clusters of blisters.
Linked to underlying gluten enteropathy (coeliac disease).
Features of dermatofibroma
Benign lesion.
Firm elevated nodules.
Usually history of trauma.
Lesion consists of histiocytes, blood vessels and fibrotic changes.
Most common cause of acanthuses nigricans
Insulin resistance
Features of dermatitis herpetiformis
itchy, vesicular skin lesions on the extensor surfaces (e.g. elbows, knees, buttocks)
Causes of erythroderma
eczema psoriasis drugs e.g. gold lymphomas, leukaemias idiopathic
Two main types of contact dermatitis
Irritant contact dermatitis
Allergic contact dermatitis
What type of hypersensitivity is allergic contact dermatitis
Type IV
Features of allergic contact dermatitis
Uncommon - often seen on the head following hair dyes. Presents as an acute weeping eczema which predominately affects the margins of the hairline rather than the hairy scalp itself.
Cement is a common cause
Features of toxic epidermal necrolysis(TEN)
systemically unwell e.g. pyrexia, tachycardic
positive Nikolsky’s sign: the epidermis separates with mild lateral pressure
Drugs known to induce TEN
phenytoin sulphonamides allopurinol penicillins carbamazepine NSAIDs
Mx of TEN
Stop precipitating factor
Supportive care
IV immunoglobulins first line
What is bullous pemphigoid
Bullous pemphigoid is an autoimmune condition causing sub-epidermal blistering of the skin. This is secondary to the development of antibodies against hemidesmosomal proteins
Features of bullous pemphigoid
itchy, tense blisters typically around flexures
the blisters usually heal without scarring
there is usually no mucosal involvement (i.e. the mouth is spared)*
What does a skin biopsy show in bullous pemphigoid
immunofluorescence shows IgG and C3 at the dermoepidermal junction
Mx of bullous pemphigoid
referral to a dermatologist for biopsy and confirmation of diagnosis
oral corticosteroids are the mainstay of treatment
topical corticosteroids, immunosuppressants and antibiotics are also used
What is pyoderma gangrenosum
Pyoderma gangrenosum is a rare, non-infectious, inflammatory disorder. It is an uncommon cause of very painful skin ulceration. It may affect any part of the skin, but the lower legs are the most common site.
What might be seen on biopsy in pyoderma gangrenosum
neutrophilic dermatoses are skin conditions characterised by dense infiltration of neutrophils in the affected tissue and this is often seen on biopsy
Causes of pyoderma gangrenosum
Idiopathic(50%) IBDs Rheumatological(RA,SLE) Haem(MDS, lymphoma) PBC
Mx of pyoderma gangrenosum
Oral steroids as 1st line
Other immunosuppressive therapy(ciclosporin)
What is seborrhoeic dermatitis thought to be due to
Seborrhoeic dermatitis in adults is a chronic dermatitis thought to be caused by an inflammatory reaction related to a proliferation of a normal skin inhabitant, a fungus called Malassezia furfur
Features of seborrhoeic dermatitis
eczematous lesions on the sebum-rich areas: scalp (may cause dandruff), periorbital, auricular and nasolabial folds
otitis externa and blepharitis may develop
Conditions associated with seborrhoeic dermatitis
HIV
Parkinson’s disease
Management of seborrhoeic dermatitis on scalp
over the counter preparations containing zinc pyrithione (‘Head & Shoulders’) and tar (‘Neutrogena T/Gel’) are first-line
the preferred second-line agent is ketoconazole
selenium sulphide and topical corticosteroid may also be useful
Management of face and body seborrhoeic dermatitis
topical antifungals: e.g. ketoconazole
topical steroids: best used for short periods
difficult to treat - recurrences are common
Which factors can exacerbate psoriasis
trauma
alcohol
drugs
steroid withdrawal
Drugs which can exacerbate psoriasis
beta blockers, lithium, antimalarials (chloroquine and hydroxychloroquine), NSAIDs and ACE inhibitors, infliximab
Indicators of atopic dermatitis/eczema
Visible flexural eczema involving the skin creases, such as the bends of the elbows or behind the knees
Personal history of flexural eczema
Personal history of asthma or allergic rhinitis
Mx of mild eczema
Generous amounts of emollients
Topical hydrocortisone 1%
Mx of moderate eczema
Emollients
Betamethasone valerate 0.025%
Consider trial of cetirizine if itch or urticaria
Preventative treatment in eczema
Maintenance regimen of topical corticosteroids
Topical calcineurin inhibitors(tacrolimus) as second line
When should hospital admission be made for eczema
Eczema herpeticum(widespread herpes simplex virus)
Antibiotic of choice in infected eczema
Flucloxacillin
Causes of folliculitis
Bacteria - staph aureus
Hot tub folliculitis (pseudomonas)
Eosinophilic folliculitis(HIV/AIDS)
