Dermatology Flashcards
Give the pathophysiology of acne vulgaris?
Acne is caused by chronic inflammation with or without localised infection in the pilosebaceous unit.
Acne results from increased production of sebum, trapping of keratin and blockage of the piloseaceous unit.
Why is acne exacerbated by puberty?
androgenic hormones increase the production of sebum, and it improves with anti-androgenic hormonal contraception.
Which bacteria is felt to be the most important in acne vulgaris development?
Propionibacterium acnes bacteria as it colonises the skin. excessive growth of this bacteria can exacerbate acne and many treatments aim to reduce these bacteria.
What are the terms used to describe lesions in acne vulgaris?
Macules: flat marks
Papules: small lumps
Pustules: small lumps with yellow pus
Comedones: skin coloured papules representing blocked pilosebaceous units
Blackheads: open comodones with black center
Ice pick scars
Hypertrophic scars: small lumps that remain after lesions heal
Rolling scars: irregular wave-like irregularities after lesion heals
What is the management of acne vulgaris?
treatment is based on a stepwise fashion:
- no treatment if mild
- Topical benzoyl peroxide reduces inflammation, helps unblock skin and is toxic to P. acnes bacteria
- topical retinouds slow production of sebum
- topical antibiotics
- oral antibiotics
- COCP
- isotretinoin in a last line effective option (oral retinoids)
Describe the usage of isotretinoin in acne vulgaris
It is a retinoid and works by reducing the production of sebum, reducing inflammation and bacterial growth.
Can only be prescribed by a dermatologist as is teratogeic.
What are the side effects of isotretinoin?
- dry skin and lips
- photosensitivity
- depression, anxiet, aggressiona nd suicidal ideation
- rarely SJS and toxic epidermal necrolysis
What is the pathophysiology of arterial ulcers
Occurs due to poor blood supply to the skin due to peripheral arterial disease
What are the distinguishing features of an arterial ulcers?
Absent pulses Pallor Tend to be smaller More regular boarder Grey colour due to poor blood supply Less likely to bleed More painful than venous ulcers Pain at night when legs elevated Pain worse on elevating the leg, improved by hanging
What is the management of arterial ulcers?
- Treating underlying cause
- Good wound care (debridement, cleaning, dressing, abs)
- Tissue viability nurse and district nurse input
- plastic surgery input
What is eczema?
It is a chronic atopic condition caused by defects in the skin barrier leading to inflammation in the skin.
There is a genetic component to eczema however there is no single inheritance pattern.
What is the presentation of eczem?
Usually presents in infancy with dry, red, itchy and sore patches of skin over the flexor surfaces and on the face and neck.
Patients experience periods of flares
What is the pathophysiology of eczema?
Tiny gaps in the skin barrier provide entrance for irritants, microbes and allergens that create an immune response resulting in inflammation and associated symptoms
What is the management for eczema?
EMOLIENTS!!!
Flares can be treated with thicker emollients, topical steroids and treating complications such as infections.
Specialist treatments include:
- zinc impregnated bandages
- topical tacrolimus
- phototherapy
- systemic immunosuppressants
What is the role of topical steroids in eczema?
General rule: weakest steroid for the shortest period required.
SE:
- thinning of the skin
- lead to more flares
- bruising
- tearing
- stretch marks
- telangiectasia
What is the steroid ladder used in eczema?
Mild: Hydrocortisone 0.5%, 1% and 2.5%
Moderate: Eumovate (clobetasone butyrate 0.05%)
Potent: Betnovate (betamethasone 0.1%)
Very potent: Dermovate (clobetasol propionate 0.05%)
HELP EVERY BABY DERMATOLOGIST
What is the most common bacterial infection in eczema?
Staph aureus which is treated with flocloxacillin.
What is Eczema herpeticum?
Viral skin infection in patients with eczema caused by the HSV or VZV.
What is the presentation of eczema herpeticum?
Patient with eczema develops:
- widespread, painful vesicular rash
- with systemic syx such as fever, lethargy, irritability and reduced oral intake.
- lymphadenopathy
What is the management of eczema herpeticum?
Tx usually started based on clinical appearance.
Aciclovir. Mild or moderate = oral whereas more severe = IV aciclovir.
How is eczema herpeticum diagnosed?
Viral swabs of the vesicles can be used to confirm diagnosis but treatment is started based on clinical appearance.
What is basal cell carcinoma?
The most common form of skin cancer but metastasis is rare as they are slow growing.
What are the risk factors for basal cell carcinoma?
- fair skin
- sun exposure
Describe the presentation of basal cell carcinoma
Typically: pearly nodule with a raised, red edge. May be scaly. Often on the face.
What is the treatment for basal cell carcinomas?
Surgical excision is treatment of choice: 3mm margin usually adequate.
Can also be treated topically:
- Imiquimod
- do not treat topically if on head or neck
- cryotherapy may be suitable
Define cellulitis
It is an infection of the skin and the soft tissues.
This is caused due to a breach of the skin barrier which may be due to trauma, eczematous skin, fungal nail infections or ulcers
Describe the presentation of cellulitis
Skin will demonstrate:
- erythema
- hot to touch
- tense
- thickened
- oedematous
- Bullae
- gold-yellow crust can be present and indicate staph aureus infection
What are the causes of cellulitis?
Most common causes:
- Staph. aureus
- Group A strep
- Group C strep
Other causes:
- MRSA
What is the eron classification used for?
It is the classification for severity of cellulitis:
- No systemic toxicity or comorbidity
- systemic toxicity or comorbidity
- Significant systemic toxicity or significant comorbidity
- Sepsis or life-threatening.
Class 3 or 4: IV antibiotics
What is the treatment of celllulitis?
First line: Flucloxacillin 500mg
Others:
- clarithromycin
- clindamycin
- co-amoxiclav
What are the two main types of contact dermaittis?
- irritant contact dermatitis
2. Allergic contact dermatitis
Describe the features of irritant contact dermatitis
- common
- non-allergic reaction due to weak acids or alkalis
- often seen on the hands
- erythema is typical
- crusting and vesicles are rate
Describe the features and management of allergic contact dermatitis
- Type IV hypersensitivity reaction
- 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
- Topical treatment with potent steroid is indicated
Define the causative agents of cutaneous fungal infections
fungal infections of the body are tinea corporis and of the groin is tinea cruris
Primary caused by dermatophytes such as trichophyton rubrum
What are the risk factors for cutaneous fungal infections?
- hot humid environments
- wearing tight fitted clothing
- obesity
- hyperhidrosis
Describe the diagnosis of cutaneous fungal infections?
Based on clinical features:
- scaly, itchy skin
- there may be single or multiple red or pink, flat or slightly annular patches varying sizes
- typically lesions have an active red, scaly advancing edge and a clear central area
Describe the assessments of suspected cutaneous fungal infections?
- history
- Examination of pattern, extent and severity
- skin sampling for fungal microscopy and culture
What is the initial management for cutaneous fungal infections?
- advice on self-care
- advice on tx with topical anti-fungal cream
- prescribing short-term corticosteroid e.g. hydrocortisone
- consider oral anti-fungal e.g. terabinafine first line depending on fungal microscopy
- managing concomitant fungal infection elsewhere to reduce risk of reinfection
What is the treatment for persistant signs of infection in cutaneous fungal infections?
- manage non-adherance
- skin sampling for fungal microscopy and culture
- oral anti-fungal treatment based on microscopy
Define cutaneous warts
small, rough growths that are caused by infection of kertainocytes with HPV.
Common in infants and very young children
How are cutaneous warts transmitted?
Skin-to-skin contact or indirectly via contact with contaminated floors or surfaces
Describe the presentation of cutaneous warts
- common warts are firm and raised with a rough surface
- periungal warts are common around the nails and can be painful
- plane warts usually round, flat-topped and skin coloured
- Palmer and plantar warts grow on palms and the soles of the feet (verrucae).
How are cutaneous warts diagnosed?
Based on clinical appearance
What is the management of cutaneous warts?
Usually resolve without treatment.
- advice on reducing risk of transmission
- tx options for non-facial warts in adults: salicylic acid, cryotherapy
Define dermatitis herpatiformis
A rare but persistent immunibullous disease that has been linked to coeliac disease
What is the genetic link with dermatitis herpetiformis?
genetic predisposition with an association with (HLA) DQ2 and DQ8
What are the causes of dermatitis herpetiformis?
- DH and coeliac disease are due to intolerance to the gliadin fraction of gluten
- Gluten triggers production of IgA antibodies and an autoimmune process that targets the skin and gut
- The majority of patients with dermatitis herpetiformis also have fluten-sensitive enteropathy
What are the clinical features of dermatitis herpetiformis?
- symmetrical distribution
- most commonly on scalp, shoulders, buttocks, elbows and kness
- characterised by prurigo and vesicles
- appear in groups or serpigious clusters
- lesions resolve to leave postinflammatory hypo- and hyper-pigmentation
How is dermatitis herpetiformis diagnosed?
Skin biopsy:
- necessary to confirm DH
Screen for nutritional deficiencies
- commonly offered same blood tests used for CD
Diagnostic blood tests:
- IgA anti-endomysial antibodies
- IgA tissue transglutaminase, tTG
- IgA and IgG deamidated gliadin peptide, dGP
- IgA and IgG gliadin assay
- total IgA level
Small intestinal biopsy
What is the management of dermatitis herpetiformis?
Gluten free diet
Medication:
- Dapsone
- reduces itch within 3 days
Define folliculitis
An infection that originates within a single hair follicle, usually caused by staph aureus
Describe the clinical features of folliculitis
- Characterised by burning and itching
- pain on manipulation of the hair
- pustules in the hair follicles
What is the management of folliculitis
GENERAL MEASURES:
- systemic abs: fluclox
- topical 2% mupirocin
Hot-tub folliculitis:
- ciprofloxacin
Gram-negative folliculitis:
- high dose trimethoprim
Define head lice
They are the Pediculus humanus capiatis parasite which causes infestations of the scalp.
They are spread by close contact with soemone that has head lice.
Describe the presentation of head lice
Infestation causes an itchy scalp. Often the nits (eggs) and even lice themselves are visible when examining the scalp
What is the management of head lice?
Dimeticone 4% lotion can be applied to hair and left for 8 hours then washed off.
Process repeated 7 days later to kill any head lice that have hatched since treatment
Special fine combs can be used to systematically comb the nits and lice out.
Define impetigo
a superficial bacterial skin infection usually caused by the staph aureus bacteria.
Less commonly caused by the strep puyogenes bacteria.
Impetigo is contagious
What causes impetigo?
Impetigo occurs when bacteria enter via a break in the skin.
What is non-bullous impetigo?
Typically occurs around the nose or mouth.
often unsightly but do not cause systemic symptoms
What is the treatment for non-bullous impetigo?
Topical fusidic acid can be used for localised.
NICE guidelines: first line used antiseeptic cream (hydrogen peroxide 1% cream)
Oral fluclox to treat more widespread or severe.
need to be off school until all lesions have healed or they have been treated with antibiotic for at least 48 hours
What is the cause of bullous impetigo?
Always caused by staph aureus bacteria. These bacteria can produce epidermolytic toxins that break down proteins that hold skin cells together. This causes fluid filled vesicles to form on skin and burst creating a “golden crust”
Whom does bullous impetigo usually affect?
- More common in neonates and children under 2 years
- more common for patients to have systemic symptoms
- in severe infections where the lesions are widespread, it is called staphylococcus scalded skin syndrome
How is bullous impetigo diagnosed?
Swabs of the vesicles can confirm the diagnosis, bacteria and antibiotic sensitivities
What is the treatment of bullous impetigo?
Fluclox
Give the aetiology of malignant melanomas
- far less common than other skin cancers
- may arise in a pre-existing naevus
- common in people with non-pigmented skin who have been exposed to excessive sunlight
How does malignant melanoma spread?
Via superficial lymphatics to give satelite lesions, to regional lymph nodes via deep lymphatics and via haeatogenous spread to the lung, liver and brain.
What are the risk factors for malignant melanoma?
- intense and intermittent sunlight and UV radiation exposure
- high numbers of benign naevi and dysplastic naevi
- FHx
- Previous hx of 3 or more severe sun burns
- blue or green eye colour
- immunosuppression
- sun sensitivity/unable to tan
What are the clinical features of a malignant melanoma?
Can occur anywhere in the body but most common:
- face and neck
- Lower extremities
- on the trunk
- change in size
- change in colour
- change in outline
- itching
- may bleed or ulcerate
- signs and symptoms of mets
What are the investigations for malignant melanoma?
Key investigation is excision biopsy
- 2mm margin
Further investigations: - FBC Urine melanogens - CXR - LFTs - CT - Sentinel node biopsy
What is the cause of pressure ulcers?
caused when an area of skin and the tissues below are damaged as a result of being placed under pressure sufficient to impair its blood supply.
What is the management of pressure sores?
- documentation of site, size and number
- pressure relief is vital
- instigate preventative measures for other sites
- investigate for other pressure sore risk factors and treat
- avoid maceration of skin by swear, urine or pus
- ensure patient has adequate nutrition
- surgical measures
What are the risk factors for pressure sores?
- immobility
- incontinence
- other moisture at site
- reduced sensation
- hypotension
- oedema
- dehydration
- septicaemia
- malnutrition
Define psoriasis
A chronic autoimmune condition that causes recurrent symptoms of psoriatic skin lesions.
Describe the presentation of psoriasis
Patches which are dry, flaky, scaly, faintly erythematous that appear raised.
Commonly over the extensor surfaces of the elbows and knees and on the scalp.
Give the different types of psoriasis
Plaque psoriasis
Guttate psoriasis
Pustular psoriasis
Erythrodermic psoriasis
Give the features of plaque psoriasis
- thickened erythematous plaques with silvery scales
- commonly on extensor surfaces and scalp
- most common form of psoriasis in adults
Give the features of guttate psoriasis
- second most common form of psoriasis and commonly occurs in children
- presents with many small raised papules across the trunk and limbs
- papules are mildly erythematous and can be slightly scaly
- over time papules turn into plaques
- often triggered by streptococcal throat infection, stress or medication
- often resolves spontaneously within 3-4 months
Give the features of pustular psoriasis
- rare severe form of psoriasis
- pustules form under areas of erythematous skin
- pus is not infectious
- patients can be systemically unwell
- treated as a medical emergency
Give the features of erythrodermic psoriasis
- rare severe form
- extensive erythematous inflamed areas covering most of the surface area of the skin
- skin comes away in large patches resulting in raw exposed areas
- treated as a medical emergency
What are the specific signs suggestive of psoriasis?
Auspitz sign: refers to small points of bleeding when plaques are scraped off
Koebner phenomenon: refers to the development of psoriatic lesions to areas of skin affected by trauma
Residual pigmentation: of the skin after the lesions resolve
What is the management of psoriasis?
Depends on the severity of the condition. Treatment options include:
- Topical steroids
- Topical vitamin D analogues
- Topical dithranol
- Topical calcineurin inhibitors (tacrolimus)
- Phototherapy with narrow band UVB light (particularly useful in guttate psoriasis)
Dovobet and Enstilar are not licensed for use in children but contain both potent steroid and vitamin D analogue
Define rosacea
Is a chronic, inflammatory skin condition predominantly affecting the convexities of the centrofacial region
Describe the diagnosis of rosacea
If there is at least one diagnostic or two major clinical features present:
Diagnostic:
- phymatous changes
- persistant erythema
Major:
- flushing/transient erythema
- papules and pustules
- telangestacia
- eye symptoms
What is the cause of rosacea
Exact cause is unknown but likely to be multifactorial such as:
- increasing age
- photosensitive skin types
- UV radiation exposure
- smoking/alcohol
- spicy foods and hot drinks
- heat/cold
- emotional stress and exercise
- colonisation with demodex folliculorum mites
Describe the management of rosacea
- providing advice on sources of information and support
- providing advice of self management
- prescribing first line topical and/or oral drug treatments
- topical metronidazole for mild
- topical brimonidine for persistent erythema
- topical ivermectin for mild-to-moderate papules/pustules
- addition of oral doxycycline for moderate-to-severe papules/pustules
What are scabies?
Tiny mites called Sarcoptes scabiei that burrow under the skin causing infection and intense itching.
They lay eggs in the skin leading to further infection and symptoms.
It can take upto 8 weeks for any symptoms or rash to appear after the initial infestation
Describe the presentation of scabies
incredibly itchy small red spots, possibly with track marks where the mites have burrowed.
Classic location of the rash is between the finger webs, but it can spread to the whole body
What is the management of scabies?
Perimethrin cream:
- to the whole body and left for 8-12 hours and then washed off
- this needs to be repeated a week later to kill all the eggs that survived the first treatment and have now hatched.
Oral ivermectin:
- as a single dose that can be repeated a week later for difficult to treat or crusted scabies
Itching can continue for up to 4 weeks after successful treatment. Crotamiton cream and chlorophenamine at night can help with the itching
What is crusted scabies?
Also known as norwegian scabies.
serious infestation with scabies in patients that are immunocomprimised.
They have patches of red skin that turn into scaly plaques rather than individual spots and burrows. Can be misdiagnosed as psoriasis.
May need admission for treatment as an inpatient with oral ivermectin and isolation
What is squamous cell carcinoma?
Is a malignant tumour of the epidermis in which the cells if differentiated show keratin formation
What are the clinical features of squamous cell carcinoma?
- develop on sun-exposed skin
- characteristically a rapidly expanding painless ulcerated nodule rolled indurated margin
- lesion may have areas of bleeding, ulceration or serious exudation
- about 55% of lesions occur in the head and neck region
- 25% occur on the hands and arms
- metastatic spread may occur via local draining lymph nodes and beyond
What is the management of squamous cell carcinomas?
If tumour localised and well differentiated then excisional surgery or radiotherapy
Large, poorly differentiated lesions: surgical removal of the primary lesion or surgery combined with radiotherapy or just radiotherapy
Cytotoxic chemotherapy may be used for disseminated disease
Define urticaria
They are small ichy lumps that appear on the skin. They may be associated with a patchy erythematous rash. This can be localised to a specific area or widespread. They may be associated with angioedema and flushing of the skin.
What is the pathophysiology of urticaria?
Caused by the release of histamine and other pro-inflammatory chemicals by mast cells in the skin.
This may be part of an allergic reaction in acute urticaria or an autoimmune reaction in chronic idiopathic urticaria
What are the causes of acute urticaria
Typically triggered by something that stimulates the mast cells to release histamine:
- allergies to food, medications or animals
- contact with chemicals, latex or stinging nettles
- medications
- viral infections
- insect bites
- dermatographism
What is chronic urticaria?
It is an autoimmune condition where autoantibodies target the mast cells and trigger them to release histamine and other chemicals. It can be sub-classified depending on the cause
What are the sub-classifications of chronic urticaria?
Chronic idiopathic urticaria: recurrent episodes of chronic urticaria without a clear underlying cause or trigger
Chronic inducible urticaria: episodes of chronic urticaria that can be induced by certain trigger
Autoimmune urticaria: chronic urticaria associated with an underlying autoimmune condition such as SLE
What is the management of urticaria?
Antihistamines are the main treatment.
- Fexofenadine for chronic urticaria
Oral steroids for a short course for severe flares
In very problematic cases referral to specialist for:
- anti-leukotrines
- omalizumab
- cyclosporin
Define viral exanthemas
An exanthem is an eruptive widespread rash. There are 6.
Define measles
Measles is caused by the measles virus. it is highly contagious via respiratory droplets.
What are the features of measles?
Symptoms start 10-12 days after exposure with fever, coryzal symptoms and conjunctivitis.
Koplik spots are greyish white spots on the buccal mucosa. These are diagnostic of measles.
The rash starts on the face, classically behind the ears, 3-5 days after the fever. it then spreads to the rest of the body. The rash is an erythematous, macular rash with flat lesions.
What is the management of measles?
It is self resolving after 7-10 days of symptoms.
Children should be self-isolated until 4 days after their symptoms resolve.
measles is a notifiable disease and all cases need to be reported to public health.
What are the complications of measles?
Pneumonia Diarrhoea Dehydration Encephalitis Meningitis Hearing loss Vision loss Death
Define scarlet fever
It is associated with group A strep infection, usually tonsilitis, It is not caused by a virus.
What is the cause of scarlet fever
Caused by an exotoxin produced by the strep pyogenes bacteria (group a strep).
What are the features of scarlet fever?
- red-pink, blotchy, macular rash
- rough “sandpaper” skin that starts on the trunk and spreads outwards
- patients can have red flushed cheeks
Other features:
- fever
- lethargy
- flushed face
- sore throat
- strawberry tongue
- cervical lymphadenopathy
What is the treatment for scarlet fever?
- phenoxymethylpenicillin (pencillin V) for 10 days.
- Notifiable disease
- Children kept off school until 24 hours after starting abs
What causes rubella?
Caused by the rubella virus. It is highly contagious and spread by respiratory droplets.
How does rubella present?
- milder erythematous macular rash (than measles)
- rash starts on face and then spreads to rest of the body
- mild fever, joint pain and a sore throat
- lymphadenopathy
What is the management of rubella?
Supportive and the condition is self-limiting.
Rubella is a notifiable disease and all cases should be reported to public health.
Avoid pregnant ladies cause can cause congenital rubella syndrome which is a triad of deafness, blindness and congenital heart disease
What is parvovirus B19?
Also known as slapped cheek syndrome and erythema infectiosum. It is caused by the parvovirus B19 virus.
How does parvovirus present?
- starts with mild fever, coryza and non-specific viral symptoms
- “slapped cheeks” rash
- few days later, a reticular mildly erythematous rash affecting the trunk and limbs
What is the management of parvovirus?
illness is self-limiting.
Patients that are risk of complications include immunocompromised and pregnant patients.
- these patients require serology testing to confirm diagnosis and checking of FBC and reticulocyte count for aplastic anaemia.
What is the cause of roseola infantum?
Caused by human herpesvirus 6 (HHV-6)
How does roseola infantum present?
- high fever
- non-itchy rash a few days later
What is the management of roseola infantum?
children usually recover within a week and does not need to be kept off school
Main complication is febrile seizures
What is the first line management of lichen planus?
potent topical steroids
