Rashes Flashcards
What is hyperkeratosis?
Increased thickness of keratin layer
What is parakeratosis
Persistence of nuclei in the keratin layer
What is acanthosis?
Increased thickness of epithelium
What is papillomatosis?
Irregular epithelial thickening
What is spongiosis?
Oedema fluid between squames appears to increase prominence of intercellular prickles
What are the four main reaction patterns and what is an example of each?
Spongiotic-intraepidermal oedema -Eczema Psoriadiform -Elongation of the rete ridges -Psoriases Lichenoid-basal layer damage -Lichen planus Vesicobullous blistering -Pemphigoid
What is psoriasis?
Common chronic inflammatory dermatosis
Increased epidermal hyperplasia
What is the koebner phenomenon and what exhibits it?
New lesions arising from sites of trauma
Psoriasis
What are lichenoid disorders?
Conditions characterised by damage to the basal epidermis
What does lichem planus look like?
Itchy flat-topped violaceous papules
What is the histology of lichen planus?
Irregular sawtooth acanthosis
Hypergranulosis and orthohyperkeratosis
Band-like upper dermal infiltrate of lymphocytes
Basal damage with formation of cytoid bodies
What is the primary feature of immunobullous disorders?
Blisters
What is pemphigus?
Rare autoimmune bullous disease with loss of epidermal cell adhesion integrity
Can pemphigus be fatal?
Yes
Does pemphigus respond to treatment?
Yes, Steroids
What is the most common subtype of Pemphigus?
Pemphigus vulgaris
Is Pemphigus vulgaris autoimmune?
Yes
What are the IgG auto-antibodies against in Pemphigus vulgaris?
Desmoglein 3 (maintains desmosomal attachments)
What is the pathogenesis of Pemphigus vulgaris?
Immune complexes form on cell surface
Complement activation and protease release
Disruption of desmosomes
End result is acantholysis
Produces fluid filled blisters which rupture to form shallow eroisions
What is acantholysis?
Lysis of intercellular adhesion sites
What is the characteristic of bullous pemphigoid?
Subepidermal blister
Is there acantholysis in bullous pemphigoid?
No
What is the pathogenesis of bullous pemphigoid?
Circulating antibodies IgG react with a major and/or minor antigen of the hemidesmosomes anchoring basal cells to the basement membrance
This results in local complement activation and tissue damage
What does immunoflouresence show in bullous pemphigoid?
Linear IgG and complement depositied around the BM
Older lesions show re-epithelialisation of their floor mimicking pemphigus vulgaris
What is dermatitis herpetiformis strongly associated with?
Coeliac disease
What haplotype is associated with dermatitis herpetiformis?
HLA-DQ2
What are the symptoms of dermatitis herpetiformis?
Intensely itchy symmetrical lesions affecting the elbows, knees and buttocks
What is the hallmark of dermatitis herpetiformis?
Papillary dermal microabscesses
What does immunoflourescence show in dermatitis herpetiformis?
IgA deposits in dermal papillae
What is the pathogenesis of dermatitis herpetiformis?
IgA antibodies target gliadin component of gluten but cross react with connective tissue matrix proteins
Immune complexes form in the dermal papillae and activate complement and generate neutrophil chemotaxins
Is Acne vulgaris common?
Very
Where does acne affect?
Sebaceous gland sites
Face
Upper back
Anterior chest
What is the pathogenesis of acne?
Increased androgens at puberty
Increased androgen sensitivity of sebaceous glands
keratin plugging of pilosebaceous units
Infection with anaerobic bacterium corynebacterium acnes
Which gender is more commonly affected with rosacea?
Females
What are the signs of rosacea ?
Pustules Recurrent facial flushing Visible blood vessels Vascular ectasia Thickening of skin - Rhinophyma patchy inflammation with plasma cells Perifollicular granulomas Follicular demodex mites
What can trigger rosacea?
sunlight
Alcohol
Spicy food
Stress
What drugs do some rosacea cases respond to?
Tetracyclines
