Revision Checklist Topics Flashcards
Psoriasis - what is it and who gets it?
Long-lasting autoimmune disease characterised by epidermal hyperplasia and increased epidermal turnover, resulting in red, itchy and scaly patches of skin. Cause is known but largely thought to be genetic and triggered by environmental factors
Areas of the body most commonly affected: extensor surfaces (back of forearms, shins, navel area and scalp
Men and women are equally affected and the condition can arise at any age, but most commonly starts in adulthood.
Psoriasis - what are the different forms of this condition and how do they present?
Plaque (psoriasis vulgaris) - approx 90% of cases, presents with red patches and white scales on top
Guttate - drop-shaped lesions
Inverse - red patches form in skin folds
Pustular - small, non-infectious pus-filled blisters
Erythrodermic - widespread rash, can develop from any of the other types
Psoriasis - what changes might be seen in the body, other than the skin?
Nail changes - pitting, changes in colour, subungual hyperkeratosis, onycholysis
In some cases, psoriatic arthritis may also develop
Psoriasis - management
No cure, but various treatments can be employed to help control the symptoms
Steroid creams/Oral steroids
Vitamin D3 creams
UVA light treatment
Immunosuppressives e.g. methotrexate
Worsened by some medications e.g. beta-blockers, NSAIDs
Clinical examination of a rash - what are the three categories than need to be assessed?
Distribution and Configuration
- Widespread or localised?
- Unilateral? Bilateral? Symmetrical?
- Which areas are affected?
- Noticeable pattern in how the lesions are arranged?
Morphology
- Colour
- Size
- Raised or flat?
- Borders
- Surface features e.g. scale, crust
Blanching and Non-blanching rashes - what is the term given to a non-blanching rash? Why does it not blanch? Name one very important condition that presents with a non-blanching rash
Purpura - a purpuric rash is one that does not blanch due to extravasation of blood
Meningitis presents with a non-blancing rash
What terms are used to describe flat lesions?
What term is given to a rash that is completely flat?
Macule if <1cm
Patch if >1cm
A macular rash
What terms are used to describe raised lesions?
What term is used to describe a rash that is elevated?
How about if a rash has areas that are both flat and elevated?
Papule if the elevated area is <0.5cm
Nodule if the elevated area is >0.5cm
A papular rash is one that is raised
If a rash has both flat and elevated areas, it is termed maculopapular
Give some of the different types of nodule that may occur in a raised rash
Plaque - raised edge and flatter surface
Wheal - compressible dermal swelling
Vesicles and Bullae - fluid-filled
Cyst - nodule containing semi-solid material
Pustule - contains pus
Define the following terms…
- Hyperkeratosis
- Parakeratosis
- Acanthosis
Hyperkeratosis - increased thickness of the keratin layer
Parakeratosis - persistence of nuclei in the keratin layer
Acanthosis - thickening of the whole epidermis
From superficial to deep, what are the four layers of the epidermis?
Keratin layer
Granular Layer
Prickle Cell Layer
Basal cell layer
Eczema (aka dermatitis) - what is the common feature of all eczema cases?
What are the two phases of eczema? List some features of each stage
Itch! Common feature of all eczemas
Acute phase - papulovesicular, red (erythematous) lesions, oedema (spongiosis) and ooze or scaling and crusting
Chronic phase - thickening (lichenification), elevated plaques, increased scaling
Name some forms of dermatitis (7)
Contact allergic - delayed (Type IV) hypersensitivity
Contact irritant - trauma e.g. soap, water etc.
Atopic - genetic and environmental factors
Drug-related - Type I or Type IV hypersensitivity
Photo-induced/photo-sensitive - reaction to UV light
Lichen simplex - caused by physical trauma to skin e.g. scratching
Stasis - caused by physical trauma to skin e.g. hydrostatic pressure due to stasis of blood
Contact dermatitis - very briefly describe the pathophysiology of this condition
Upon antigen challenge, specifically sensitised T cells proliferate and migrate to the skin, resulting in inflammation = dermatitis
Contact dermatitis - how is this condition tested for?
Patch testing
How to contact allergic and contact irritant forms of dermatitis differ from one another?
Contact irritant is due to non-specific physical irritation rather than a specific allergic reaction
These two conditions may be difficult to distinguish from one another, and the two may co-exist
Atopic eczema - signs and symptoms
Pruritus (itch)
Ill-defined erythema and scaling
Generalised dry skin
Flexor surface distribution
Associated with other atopic diseases e.g. asthma, allergic rhinitis, food allergies etc.
Atopic eczema - what chronic changes may be seen in this condition?
What does crusting indicate?
Lichenification
Excoriation
Secondary infection. Crusting indicates Staph aureus infection
Atopic eczema - what infectious organism may cause secondary infection in someone with atopic eczema that results in “monomorphic punched-out lesions”?
Herpes simplex virus causing Eczema herpeticum
Atopic eczema - how is this condition diagnosed?
Itching plus 3 or more of the following…
- visible flexural rash
- history of flexural rash
- personal history of atopy
- generally dry skin
- onset before 2 years old
Atopic eczema - what gene appears to be especially important in the development of this condition?
FLG gene encoding for Filaggrin
Atopic eczema - management
Plenty of emollients
Avoid irritants
Topical steroids
Treat secondary infections
Phototherapy - mainly UVB
Systemic immunosuppressants if need be
(Biologic agents…)
Define ‘spongiosis’
Oedema in the keratin layer of the epidermis, between the keratinocytes
What are the 4 reaction patterns seen in inflammatory skin diseases?
Spongiotic-intraepidermal oedema
Psoriasiform - elongation of the rete ridges e.g. psoriasis
Lichenoid - basal layer damage e.g. lichen planus, SLE
Vesiculobullous - blistering e.g. pemphigus, pemphigoid
Pemphigus - what is it?
Rare autoimmune bullous disease
Loss of integrity of epidermal cell adhesion - fault is at DEJ
4 distinct subtypes, with 80% of cases being Pemphigus vulgaris
Pemphigus vulgaris - what type of immunoglobulin is involved, and what does it target?
What is the end result?
IgG
Made against Desmoglein-3 - maintains desmosomal attachments
End result is acantholysis
Pemphigus vulgaris - clinical presentation, and what the key difference is between it and bullous pemphigoid
Involves skin especially scalp, face, axillae, groin and trunk
May also affect the mucosa in the mouth and resp tract
Result is fluid-filled blisters which rupture to form shallow erosions
Crucially, bullous pemphigoid blisters are subepidermal and there is no evidence of acantholysis
Bullous pemphigus - what is the immunological target in this condition?
What needs to be kept in mind when sending lesions for histology?
IgG attacks hemidesmosomes anchoring basal cells to the basement membrane
Early lesions need to be sent for histoloy as later lesions show re-epithelialisation and hence mimick pemphigus vulgaris
Dermatitis herpetiformis - presentation
Autoimmune bullous disease - relatively rare
Intensely itchy summetrical lesions
Elbows, knees and buttocks affected, often lesions are excoriated
Hallmark is papillary dermal microabscesses
Dermatitis herpetiformis - what disease is this condition strongly associated with?
What HLA type is this disease strongly associated with?
Disease - Coeliac disease, 90% have gluten sensitive enteropathy
HLA type - HLA-DQ2
Acne vulgaris - common sites of presentation and aetiology (including bacterial species)
Sites of presentation
- face
- upper back
- anterior chest
- (distribution reflects sebaceous glands)
Aetiology
- Increased androgens at puberty
- Increased androgen sensitivity of sebaceous glands (maybe?)
- Keratin plugging of pilosebaceous units
- Infection with anaerobic bacterium - Corynebacterium acnes
Rosacea - presentation
Common condition, affecting approx. 10% of caucasian adults
More commonly seen in females
Recurrent facial flushing
Visible blood vessels
Pustules - NO comedones
Thickening of the skin - rhinophyma (large red bumpy nose)
Rosacea - triggers
Sunlight
Alcohol
Spicy foods
Stress
Allergic reaction to mites?
What are the 4 main groups of porphyrias?
Phototoxic skin porphyrias e.g. porphyria cutanea tarda (PCT), erythropoetic protoporphyria (EPP)
Blistering and fragile skin porphyrias
Acute attack porphyrias
Severe congenital porphyrias e.g. congenital erythropoetic porphyria
Porphyria Cutanea Tarda (PCT) Type I - what enzyme is defective? What does this result in a build up of?
Defective enzyme - Uroporphyrinogen decarboxylase
Build up of Uroporphyrinogen III
Porphyria Cutanea Tarda - typical presentation and diagnosis
Most common phototoxic skin porphyria
Blisters
Fragility
Others - hyperpigmentation, hypertrichosis (excessive hair growth), solar urticaria (hives), morphoea (painless discoloured patches)
Diagnosis - typically done using a Woods lamp test, and also spectrofluorometers
PCT - management
Having established PCT, now need to establish the underlying cause…
- alcohol
- viral hepatitis
- oestrogens
- haemochromatosis
Then treatment aims to relieve the skin disease and treat the underlying cause
Erythropoietic protoporphyria (EPP) - reduced activity in what enzyme brings about this condition, and what does this lead to a build up of?
Reduced activity - Ferrochelatase
Build up of Protoporphyrin IX
EPP - presentation
Usually presents in childhood with most common presentation being acute photosensitivity of skin
A few minutes of sun exposure can produce pruritius, erythema, swelling and pain
After chronic exposure patients may develop lichenification, hypo/hyperpigmentation and scarring
EPP - investigations
Porphyrin plasma scan is best
Can also look for fluorocytes, transaminases, Hb levels etc.
EPP - management
Explain the diagnosis to the patient and arrange for LFTs and RBC porphyrins to be screened every 6 months - this is because EPP can potentially result in Liver Failure
Visible light photoprotection measures should be taken e.g. behavioural, clothing, topical sunscreen etc.
Acute Intermittent Porphyria - what enzyme is reduced in activity and what does this lead to a build up of?
Reduced activity - PBG deaminase
Build up of Porphobilinogen (PBG)
Acute Intermittent Porphyria - signs and symptoms
Severe and poorly localised abdominal pain is very common
Urinary signs - painful urination, urinary retention or incontinence, darkened urine etc.
Other very general signs - anxiety, depression, nausea, vomiting, headache, tachycardia, hypertension etc.
What is the most common type of drug eruption? What other types are there?
Most common - exanthematous drug eruption (90%)
Urticarial (5-10%)
Papulosquamous/pustular/bullous
Also pigmentation, itch/pain, photosensitivity
What kind of hypersensitivity is an exanthematous drug eruption?
How does it present?
Type IV - delayed and T-cell mediated
Usually mild and self-limiting, symmetrical widespread rash
Itch and mild fever are common
Onset is 4-21 days after first taking the drug
What features might suggest that an exanthematous drug eruption is potentially severe?
- Involvement of the mucous membranes and the face
- Facial oedema and erythaema
- Fever
- Blisters, purpura and necrosis
- Lymphadenopathy, arthralgia
- SoB, wheezing
List some of the drugs associated with erythematous drug eruptions
Penicillins
Sulphonamide antibiotics
Erythromycin
Streptomycin
Allopurinol
NSAIDs
Phenytoin
Chloramphenicol
What kind of hypersensitivity reaction is an urticarial drug eruption?
Type I - IgE-mediated allergic reaction
List some types of pustular/bullous drug eruptions and what medications might cause them
Acne
- Glucocorticoids
- Androgens, lithium, isoniazid, phenytoin
Acute Generalised Exanthematous Pustulosis (AGEP) - rare
- Antibiotics
- CCBs
- Antimalarials
Drug-enduced Bullous Pemphigoid
- ACE inhibitors
- Penicillin
- Furosemide
Severe Cutaneous Adverse reactions can be life threatening! Name some of these conditions
Steven-Johnson Syndrome
Toxic Epidermal Necrolysis
Drug reaction with eosinophilia and systemic symptoms (DRESS)
Acute Generalised Exanthematous Pustulosis (AGEP)
