Pathology Flashcards
Functions of the skin
Strong barrier to antigens and organisms Thermoregulation Fluid and electrolyte balance Endocrine function Protection from UV rays Immune function Sensory function
Ground substances in the dermis
Hyaluronic acid and chondroitin sulphate
Which type of the dermis contains appendage structures?
Reticular dermis
Acanthosis
Increase in thickness in epithelium. Hyperplasia
Hyperkeratosis
Increased thickness in the keratin layer
Parakeratosis
Persistence of nuclei in the keratin layer
Papillomatosis
Irregular epithelial thickening
Spongiosis
Oedema fluid between squames appears to increase the prominence of intercellular prickles.
4 main reaction patterns in skin
Spongiotic-intraepidermal oedema
Psoriasiform
Lichenoid
Vesiculobullous
Psoriasiform
Elongation of the rete ridges
Which condition is spongiotic-intraepidermal oedema seen in?
Eczema
Which condition is psoriasiform seen in?
Psoriasis
Which condition is lichenoid seen in?
Lichen planus and lupus
Which conditions is vesiculobullous seen in?
Pemphigoid, pemphigus and dermatitis herpetiformis
What are lichenoid disorders?
Damage to basal epidermis
Histology in lichenoid disorders
Irregular saw tooth acanthosis
Hypergranulosis and orthohyperkeratosis
Band-like upper dermal infiltrate of lymphocytes
Basal damage with formation of cytoid bodies
Prototypic condition in lichenoid disorders
Lichen planus
Disorders falling under the heading lichenoid disorders
Lichen planus (main) Discoid lupus Some drug rashes Erythema multiforme Toxic epidermal necrolysis
Main primary feature of immunobullous disorders
Blisters
True or false: pemphigus is a common autoimmune bullous disease
False - it is a rare autoimmune bullous disease
What happens to the epidermis in pemphigus?
There is loss of integrity of epidermal cell adhesion
Which type of drugs does pemphigus respond to?
Steroids
Most common subtype of pemphigus
Pemphigus vulgaris
In pemphigus vulgaris, __ antibodies are made against __ _
IgG antibodies are made against desmoglein 3
What does desmoglein 3 maintain?
Desmosomal attachments
Steps in pemphigus vulgaris that leads to acantholysis
IgG antibodies against desmoglein 3 Immune complexes form on cell surface Complement activation and protease release Disruption at desmosomes End result is acantholysis
Which parts of the body are most commonly affected by pemphigus vulgaris?
Skin - face, scalp, axillae, groin, trunk
Which parts of the body may be affected by pemphigus vulgaris, but are not as common as skin?
Mucosa. Extensive mucosal involvement may be fatal
Investigations for pemphigus vulgaris
Microscopy or fluorescence imaging
What is bullous pemphigoid?
A condition where there is development of a subepidermal blister
True or false: there is acantholysis in bullous pemphigoid
False - there is no evidence of acantholysis
Pathophysiology of bullous pemphigoid
Circulating IgG antibodies react with antigen of the hemidesmosomes anchoring basal cells to basement membrane, resulting in local complement activation and tissue damage
What does immunofluorescence show in bullous pemphigoid?
Linear IgG plus complement deposited around the basement membrane
What do older lesions of pemphigoid show?
Re-epithelialisation of their floor, mimicking pemphigus vulgaris
What does immunofluorescence in pemphigus vulgaris show?
Intraepidermal IgG
What is dermatitis hepatoformis?
An autoimmune bullous disease
Which condition does dermatitis hepatoformis have a strong association with?
Coeliac disease
Clinical presentation of dermatitis hepatoformis
Intensely itchy lesions which are usually symmetrical, commonly found on the elbows, knees and buttocks
Hallmark of dermatitis hepatoformis
Papillary dermal microabscesses
Histology in dermatitis hepatoformis
Papillary dermal micro abscesses and deposits of IgA found in dermal papillae
Pathogenesis of dermatitis hepatoformis
IgA antibodies target gliadin component of gluten but cross react with connective tissue matrix proteins
Immune complexes form in dermal papillae and activate complement and generate neutrophil chemotaxis
What does distribution of acne vulgaris reflect?
Sebaceous gland sites - face, upper neck, anterior chest
Aetiology of acne vulgaris
Increased androgens at puberty
Perhaps increased androgen sensitivity of sebaceous glands
Keratin plugging of pilosebaceous units
Infection with bacterium Corynebacterium acnes
Bacteria that causes acne
Corynebacterium acnes
Which gender is rosacea most common in?
Females
Clinical presentation of rosacea
Recurrent facial flushing, visible blood vessels, pustules, thickening of the skin - rhinopehyma
Triggers of rosacea
Sunlight, alcohol, spicy foods, stress
Pathology in rosacea
Vascular ectasia Patchy inflammation Look for plasma cells and pustule formation Perifollicular granulomas Follicular demodex mites often noted Perhaps allergic reaction to mites
