Pathology

Question 1

Name functions of the skin

Answer 1

• strong barriers to antigens and organisms
• thermoregulation BV and sweat glands
• endocrine function UV stimulation of vitamin D
• protection from UV rays melanin pigment
• immune function langerhans cells
• sensory function; touch, temperature and pressure

Question 2

Describe the normal epidermis

Answer 2

• stratified keratinising squamous epithelium
• prickle cells prominent desmosomes
• granular layer rich in keratohyalin granules
• corneal layer differentiated keratinised cells
• corneocytes, shed from surface house dust
• melanocytes found in basal layer
• langerhans cells

Question 3

Describe the dermis

Answer 3

• matrix of type 1 and type 111 collagen
• elastic fibres
• ground substance hyaluronic acid and chondroitin sulphate
• papillary dermis is thin and lies just beneath epidermis
• reticular dermis thicker bundles type 1 collagen
• reticular dermis contains appendage structures- sweat glands, pilosebaceous units
• epidermal BM made of laminin and collagen IV

Question 4

What is hyperkeratosis?

Answer 4

Increased thickness of keratin layer

Question 5

What is parakeratosis?

Answer 5

Persistence of nuclei in the keratin layer

Question 6

What is acanthosis?

Answer 6

Increased thickness of epithelium

Question 7

What is papillomatososi?

Answer 7

Irregular epithelial thickening

Question 8

What is spongiosis?

Answer 8

Oedema fluid between squames appears to increase prominence of intercellular prickles. if severe, vesicle filled by oedema fluid develop

Question 9

Name the four main reaction patterns of inflammatory skin diseases

Answer 9

• spongiotic-intraepidermal oedema eg eczema
• psoriasiform; elongation of the rete bridges eg psoriasis
• lichenoid basal layer damage; eg lichen planus and lupus
• vesiculobullous blistering eg pemphigoid, pemphigus and dermatitis herpetiformis

Question 10

Describe the pathogenesis of psoriasis

Answer 10

• remains elusive
• new lesions can arise at sites of trauma (koebner phenomenon)
• ?complement mediated attack on keratin layer; munro micro abscesses
• increased epidermal turnover, epidermal hyperplasia
• ?hereditary factors
• ? assoc specific HLA types

Question 11

What are munro micro abscesses?

Answer 11

Collection of neutrophils in the upper parts of the epidermis

Question 12

What are lichenoid disorders?

Answer 12

• conditions characterised by damage to basal epidermis
• prototypic condition is lichen planus; common
• itchy flat topped violaceous papules

Question 13

Describe the histology of lichen planus

Answer 13

• irregular sawtooth acanthosis
• hypergranulosis and orthohyperkeratosis
• band like upper dermal infiltrate of lymphocytes
• basal damage with formation of cytoid bodies

Question 14

Describe immunobullous disorders

Answer 14

• vesicle and bullae occur as a secondary phenomenon in many skin diseases eg. eczema, herpes virus infection, burns
• immunobullous diseases have blisters as the primary feature

Question 15

Name some important examples of immunobullous disease

Answer 15

• pemphigus
• bullous pemphigoid
• dermatitis herpetiformis

Question 16

Describe pemphigus

Answer 16

• rare autoimmune bullous disease
• sex incidence is equal, usually middle age
• loss of integrity of epidermal cell adhesion
• variable severity - occasionally fatal
• responds to steroids
• pemphigus has 4 distinct subtypes

Question 17

Describe pemphigus vulgaris

Answer 17

• autoimmune condition
• IgG auto-antibodies made against desmoglein 3
• demsogelin 3 maintains desmosomal attachments
• immune complexes form on cell surface
• complement activation and protease release
• disruption of desmosomes
• end results is acantholysis

Question 18

Describe the appearance of pemphigus vulgaris

Answer 18

• involves skin especially scalp, face, axillae, groin, trunk
• may affect mucosa eg mouth, resp tract. extensive mucosal involvement may be fatal
• produces fluid filled blisters which rupture to form shallow erosions

Question 19

Describe bullous pemphigoid

Answer 19

• subepidermal blister
• no evidence of acantholysis
• circulating antibodies (IgG) react with a major and or minor antigen of the hemidesmosomes anchoring basal cells to basement membrane
• the result is local complement activation and tissue damage
• dermal papillae project into bulla

Question 20

What does histology show for bullous pemphigoid?

Answer 20

• immunofluorescence shows linear IgG and complement deposited around the basement membrane
• always send early lesions for histology
• older lesions of pemphigoid show re-epithelialisation of their floor, mimicking pemphigus vulgaris

Question 21

Describe dermatitis herpetiformis

Answer 21

• relatively rare condition
• autoimmune bullous disease
• strong association with coeliac disease
• associated with HLA-DQ2 haplotype
• intensly itchy lesions symmetrical
• elbows, knees and buttocks often excoriated
• hallmark is papillary dermal microabscesses

Question 22

Describe the distribution of acne

Answer 22

• distribution reflects sebaceous gland sites

- face, upper back, anterior chest

Question 23

Describe the aetiology of acne

Answer 23

• increased androgens at puberty
• ?? increased androgen sensitivity of sebaceous glands
• keratin plugging of pilosebaceous units
• infection with anaerobic bacterium corynebacterium acnes

Question 24

Describe the pathophysiology of acne

Answer 24

• sebum produced by sebaceous gland plugs pilo-sebaceous unit
• keratin and sebum build up to produce comedones (blackheads / whiteheads)
• rupture causes acute inflammation and foreign body granulomas

Question 25

Describe rosacea

Answer 25

• common condition
• around 10% prevalence in caucasian adults
• commoner in females
• recurrent facial flushing
• visible blood vessels
• pustules
• thickening of skin; rhinophyma

Question 26

Describe the pathology of rosacea

Answer 26

• vascular ectasia
• patchy inflammation with plasma cells
• pustules
• perifollicular granulomas
• follicular demodex mites often noted
• allergic reaction to mites?