Pathology of Rashes Flashcards
What are the prominent cells in the prickle cell layer?
Desmosomes
What cells make up the epidermis?
Stratified keratiising squamous epithelium
What makes up the dermis?
Matrix of type 1 and type 111 collagen, elastic fibres and ground substance (hyaluronic acid and chondroitin sulphate)
Where does the papillary dermis lie?
Thin layer that lies just beneath the epidermis
Where does the reticular dermis lie?
In thicker bundles, type 1 collagen
What does the reticular dermis contain?
Sweat glands, pilosebacous units
What is hyperkeratosis?
Increased thickness of keratin layer
What is parakeratosis?
Persistence of nuclei in the keratin layer due to the epidermis turning over too quickly
What is acanthosis?
Increased thickenss of epitheium
What is the papillomatosis?
Irregular epithelial thickening
What is spongiosis?
Oedema fluid between squames appears to increase in prominence of intercellular prickles
If severe the vesicles filled by odemea fluid develop
What is an example of papilllomatosis?
Acanthosis nigricans in diabetes which is where there is thick velvety folds in the axillae
What is an example of a spongiotic-intraepidermal oedematous disease?
Eczema
What is an example of a psoriasiform-elongartion of the rete ridges?
Psoriasis
What is an example of lichenoid-basal layer damage?
Lichen planus and lupus
What is an example of vesiculobullous-blistering?
Pemphigoid, pemphigus and dermatitis herpetiformis
What is the pathogenesis of psoriaisis?
Epidermal hyperplasia
Heriditary factors
Associated specific HLA types
Complement mediated attack on keratin layer (complement attracts neutrophils to keratin layer creating munro micro abscesses)
What is the koebner phenomenon?
New lesions can arise at site of trauma
How would you describe a psoriasis rash?
Well defined, erythematous plaque with scales on the surface
On extensor surfaces and often symmetrical
What effect can psoriasis have on the nails?
Fungal infection Onchylosis Nail dystrophy Nail pitting Subungal hyperkeratosis
What does psoriasis look like histologically?
Elongated rete ridges
Aggregates of neutrophils at the upper end of the dermis
Parakeratosis
Auspitz sign
What is auspitz sign?
Appearance of small bleeing points after successive layers of scale have been removed from the surface of psoriatic papules or plaques
What are lichenoid disorders?
Conditions characterised by damage to the basal epidermis
Itchy flat topped violaceous papules
What does lichen planus look like histologically?
Irregular sawtooth acanthosis (diffuse epidermal hyperplasia)
Hypergranulosis and orthohyperkeratosis (hyperkeratosis without parakeratosis)
Band-like upper dermal infiltrate of lymphocytes
Basal damage with formation of cytoid bodies
Where can lichen plaus affect?
Skin, mucous membranes, genetalia, scalp
What are the different types of immunobullous disorders?
Pemphigus
Bullous pemphigoid
Dermatitis herpetiformis
What is pemphigus?
An autoimmune bullous disease that causes bullae dut to a loss of integrity of epidermal cell adhesion
Why is there a loss of integrity in the epidermal cell adhesion?
IgG autoantibody is produced that attackes desmoglein 3 in prickle cell layer
What is the pathogenesis of pemphigus vulgaris?
Desmoglein 3 attacked by IgG autoantibodies
Immune compexes form on cell surface
Complement activation and protease release
Disruption of desmosomes
End result in acantholysis (lysis of epithelial cell attachments)
What areas of the skin can be affected by pemphigus vulgaris?
Skin esp. scalp, face, axillae, groin and trunk
Can affect mucosa e.g. mouth, resp. tract
Where does bullous pemphigoid attack?
Subepidermal blister with no evidence of acantholysis
Ciculating IgG antibodies attack hemidesmosomes which anchor basal cell to the basement membrane causing local complement activation and tissue damage
What does immunoflourescence show for bullous pemphiogoid?
Linear IgG and complement deposited around the basement membrane
What GI condition is dermatitis herpatiformis assocaited with?
Coeliac disease
Autoimmune bullous disease
Where is dermatitis herpetiformis most likely to present?
Elbows
Knees
Buttocks
What does dermatitis herpetiformis show histologically?
Papillary dermal microabscesses
Deposts of IgA in dermal papillae
Where is acne most common?
Face
Upper back
Anterior chest
What is the aetiology of acne?
Increased androgens at puberty which increases the activity of sebaceous glands
Pilosebacous units get plugged with keratin
Infection with anaerobic bacterum corynebacterium acnes
What are the hallmarkes of rosacea?
Recurrent facial flushing
Telangiectasia
Pustules
Thickening of skin around nose - phinophyma
What can trigger rosacea?
Sunlight
Alcohol
Spicy foods
Stress
What can be used to treat rosacea?
Tetracyclines
What is the pathology of rosacea?
Vascular ectasia Patchy inflammation with plasma cells Pustules Perifollicular granulomas Follicular demodex mites
What are the different types of psoriasis?
Psoriais vulgaris
Guttate psoriasisi
Palmoplantar pustular
Erythrodermic pustular
What systemic effects can psoriasis have?
Psoriatic arthritis Metabolic syndrome Crohn's disease Malignancies Depression Uveitis
What is the metabolic syndrome?
Obestiry
Hypertension
Diabetes
Lipid abnormalities
What therapies can be used for psoriasis?
Vitamin D analogues Coal tar Dithranol Steroid ointments Emollients UV phototherapy Immunosuppresion with methotrexate
Why is isotretinoin only able to be prescribed by secondary care?
Causes profound birth defects so patients need to be on birth control
Will initially cause a flare up of the acne before it calms down
What is the difference between a black and whitehead?
A blackhead it an open comedone
A whitehead is a closed comodone
What is the morphology of acne vulgaris?
Comedones
Pustules and papules
Cysts
Erythema
What is acne excoriee?
A type of pschogenic acne whereby patients pick at their acne causing erosions and scarring
What are the different types of topical treatment avaliable to treat acne?
Benzoly peroxide (keratolytic, antibacterial) Topical vitamin A (retinoid) - drying effect Topical antibiotics (antibacterial and anti-inflammatory)
What are the systemic treatment avaliable for acne?
Tetracycline antibiotics (antibacterial and anti-inflammatory) Isotretinoin (oral retinoid) - effect on sebacous gland activity
What is the morphology of acne rosacea?
Papules, pustules and erythema but no comedones
Prominent facial flushing exaerbated by a sudden change in temp, alcohol or spicy food
Rhinophyma
Conjunctivitis
How is rosacea managed?
Reduce aggravating factors (dietary triggers, sun exposure, avoid topical steroids)
What topical therapies are avaliable for roseacea?
Metrondiazole
Ivermectin (to reduce dermox mite)
What oral therapies are avaliable for rosacea?
Oral tetracycline
Istretinoin if severe
How can telangiectasia be managed?
Vascular laser
How can rhinophyma be managed?
Surgery/ laser shaving
What is wickham’s striae?
Fine lace-like pattern on surface of papules and buccal mucosa
How is lichen planus treated?
Topical or oral steroids
How can you remember the difference between bullous pemphigoid and pemphigus?
Bullous pemphigoiD - split is Deeper through the DEJ
PemphiguS - split is more Superficial, intra-eppidermal
What is nikolsky’s sign?
The top layers of the skin slip away from the lower layers when slightly rubbed
Indicated pemphigus
How are pemphigoid and pemphigus treated?
Systemic steroids
Other immunosuppresive agents
Pemphigoid = tetracytcline antibiotics
Topicals: emollients, topical steroids, topical sntiseptics
How is pemphigus and pemphigoid investigated?
Skin biopsy with direct immunofluorescence
Indirect immunofluroscence
