Pathology of Rashes 1

Question 1

Functions of skin?

Answer 1

• Strong barrier to antigens and organisms
• Thermoregulation
• Fluid and electrolyte balance sweat glands
• Fluid and electrolyte balance sweat glands
• Endocrine function - UV stimulation of Vit D
• Protection of UV rays
• Immune function - Langerhans
• Sensory function touch, temp, pressure

Question 2

What type of cell is mainly the epidermis?

Answer 2

Stratified keratinising squamous epithelium

Question 3

Where are melanocytes found?

Answer 3

Dermo-epidermal junction

Basal layer

Question 4

Where are langerhan cells?

Answer 4

Located in upper and mid-epidermis

Question 5

What do langerhan cells act as?

Answer 5

Sentinels monitoring environment for antigens

Important in initaiting inflammation

Question 6

What is the dermis?

Answer 6

Matrix of type 1,2 & 3 collagen
Elastic fibres
Ground substances

Question 7

Where does papillary dermis lie?

Answer 7

Just under epidermis, it is thin

Question 8

What does reticular dermis contain?

Answer 8

Sweat glands

Pilosebaceous units

Question 9

Epidermal Basal membrane made of?

Answer 9

Laminin and collagen IV

Question 10

What is hyperkeratosis?

Answer 10

Increased thickness of keratin layer

Question 11

What is parakeratosis?

Answer 11

Persistence of nuclei in the keratin layer

Question 12

What is acanthosis?

Answer 12

Increased thickness of epithelium

Question 13

Why is there no nuclei in keratin layer usually?

Answer 13

Because the cells are dead and ready to fall off

Question 14

What is papillomatosis?

Answer 14

Irregular epithelial thickening

Question 15

What is spongiosis?

Answer 15

Oedema fluid between squames appears to increase prominence of intercellular prickles
If severe vesicles filled by oedema fluid develop

Question 16

How many main reaction patterns of inflammatory skin disease?

Answer 16

4

Question 17

4 main inflammatory skin disease reaction patterns?

Answer 17

• Spongiotic-intraepidermal oedema e.g. eczema
• Psoriasiform-elongation of the rete ridges e.g. psoriasis
• Lichenoid-basal layer damage e.g. lichen planus and lupus
• Vesiculobullous-blistering e.g. pemphigoid, pemphigus and dermatitis herpetiformis

Question 18

Where psoriasis can develop?

Answer 18

-Epidermal hyperplasia
: increased epidermal turnover
Hereditary factors
New lesions can arise at sites of trauma

Question 19

What is psoraisis?

Answer 19

Complement mediated attack on keratin layer, complement attracts neutrophils to keratin layer

Question 20

Histology of psoraisis?

Answer 20

Elongation of rete ridges

Epidermis is elongated and plumped and fuses with neighboring ridges

Question 21

Psoriasis is not hereditary. True or False?

Answer 21

FALSE

Can be partly hereditary

Question 22

What are lichenoid disorders?

Answer 22

Conditions characterized by damage to basal epidermis

Question 23

What is a common lichenoid disorder?

Answer 23

Prototypic condition is lichen planus

Question 24

Symptoms of lichenoid disorder?

Answer 24

Itchy flat topped Violaceous papules

Question 25

Histology of lichen planus?

Answer 25

- Irregular sawtooth acanthosis - Hypergranulosis and orthohyperkeratosis - Band like upper dermal infiltrate of lymphocytes - Basal damage with formation of cytoid bodies

Question 26

Other lichenoid disorders?

Answer 26

Discoid lupus Drug rashes Toxic epidermal necrolysis

Question 27

What occurs as a secondary phenomenon in many skin diseases? eg eczema, HPV, burns

Answer 27

Vesicles and bullae (blisters)

Question 28

Primary feature of immunobullous diseases?

Answer 28

Blisters

Question 29

Important examples of immunobullous disorders?

Answer 29

Pemphigus Bullous pemphigoid Dermatitis herpetiformis

Question 30

Pemphigus is rare. True or false?

Answer 30

True | Rare autoimmune disease, usually middle age

Question 31

What histologically is pemphigus?

Answer 31

Loss of integrity of epidermal cell adhesion

Question 32

What does pemphigus respond to?

Answer 32

Steroids

Question 33

How many distinct sub types of pemphigus?

Answer 33

4

Question 34

80% of cases of pemphigus are sub type?

Answer 34

Pemphigus vulgaris

Question 35

What immune response happens in pemphigus vulgaris?

Answer 35

IgG auto-antibodies made against desmoglein 3

Question 36

What is the role of desmoglein 3?

Answer 36

Maintains desmosomal attachments

Question 37

Process pf auto-antibodies against desmoglein 3?

Answer 37

Immune complexes dorm on cell surface Complement activation and protease release Disruption of desmosomes END RESULT= Acantholysis

Question 38

What parts of body does pemphigus vulgaris involve?

Answer 38

Skin esp scapl, face, axillae, groin, trunk | May affect mucosa of resp tract, mouth

Question 39

What does pemphigus produce?

Answer 39

Fluid filled blisters which rupture to form shallow erosions

Question 40

What is acantholysis?

Answer 40

Lysis of intercellular adhesion sites

Question 41

What is bullous pemphigoid?

Answer 41

Subepidermal blister | -No evidence of acantholysis

Question 42

What do antibodies do in bullous pemphigoid?

Answer 42

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

Question 43

What do antibodies attack in bullous pemphigoid?

Answer 43

Hemidesmosomes | Basal membrane

Question 44

What can older lesions of bullous pemphigoid mimick?

Answer 44

Show re-epithelialization of their floor mimicking pemphigus vulgaris

Question 45

What generally is dermatitis herpetiformis?

Answer 45

Relatively rare condition Autoimmune bullous disease | -associated with celiac disease

Question 46

Haplotype of coeliacs?

Answer 46

HLA-DQ2

Question 47

Symptoms of dermatitis herpetiforms?

Answer 47

Intensely itchy lesions, symmetrical | -knees, elbows, buttocks

Question 48

Hallmark of dermatitis herpetiformis?

Answer 48

Papillary dermal microabscesses

Question 49

90% of patients with dermatitis herpetiformis have?

Answer 49

Gluten sensitive enteropathy

Question 50

What does distribution of acne vulgaris reflect?

Answer 50

Sebaceous gland sites

Question 51

Aetiology of acne?

Answer 51

Increased androgens at puberty Increased androgen sensitivity of sebaceous glands Keratin plugging of pilosebaceous units Infection with anaerobic bacterium- corynebacterium acnes

Question 52

Process of acne?

Answer 52

- Sebum produced by sebaceous gland plugs pilo-sebaceuos unit - Keratin and sebum build up to produce comedones (blackheads / whiteheads) - Rupture causes acute inflammation + foreign body granulomas

Question 53

What is rosacea?

Answer 53

Recurrent facial flushing Visible blod vessels Pustules Thickening of skin (rhinophyma)

Question 54

Triggers of rosacea?

Answer 54

Sunlight Alcohol Spicy foods Stress

Question 55

Pathology of rosacea?

Answer 55

- Patchy inflammation with plasma cells - Pustules - Perifollicular granulomas - Follicular demodex mites often noted - Allergic reaction to mites?

Question 56

Antibody reaction in dermatitis herpetiformis?

Answer 56

- Shows deposits of IgA in dermal papillae - IgA ABs 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 chemotaxins