Dermatology

Question 1

What rash is associated with coeliac disease

Answer 1

dermatitis herpeticum

Question 2

Describe dermatitis herpeticum rash

Answer 2

Pruritic papulovesicular rash affecting both elbows and back

Question 3

Underlying mechanism of keloid scars

Answer 3

Excess collagen production (fibroblast)

Question 4

What is a keloid scar

Answer 4

Raised thickened area at site of previous skin injury

Question 5

Histology of alopecia

Answer 5

T cells within peribulbar infiltration that release cytokines and chemokines -> reject hair -> hair loss

Question 6

Aeitology of tuberous sclerosis

Answer 6

mutations of TSC1 gene on chromosome 9 or TSC2 gene on chromosome 16 (most common)

50% autosomal dominant
50% sporadic

Question 7

What does TSC1 gene code for?

Answer 7

hamartin

Question 8

What does TSC2 gene code for

Answer 8

tuberin

Question 9

Pathophysiology of tuberous sclerosis

Answer 9

Hamartin and tuberin form a regulatory complex that acts to limit the activity of rapamycin complex 1

Mutations here lead to poorly controlled cell growth

Question 10

Clinical presentation of tuberous sclerosis

Answer 10

Epilepsy
Learning disability
Hypomelanotic macules, ash-leaf macules, shagreen patches, adenoma seabeecum
Eyes -retinal hamartomas
Cardiac rhabomyomas

Question 11

Investigations

Answer 11

Wood light

Question 12

Risk factors for psoarsis

Answer 12

Positive family history
Genetics - guttate psoarsis ass. with HLA-BW17, HLA-BLA13, HLA-C6
Infection
Sunlight

Question 13

What is Koebnar phenomen

Answer 13

psoarsis occurring on pervious areas of trauma

Question 14

Pathophysiology of psoarasis

Answer 14

T cell immune-mediated autoimmune disorder
T helper cells produce inflammatory cytokines - inc. interlukin-IL 17 AND IL 22 and tumour necrosis factor

These stimulate proliferation of. keratinocytes and production of dermal antigen adhesion molecule in local blood vessels -> stimulates cytokine release

Increases skin cell turnover - immature skin cells migrate to surface with dead skin cells remaining ->. plaque lesions

Question 15

Typical tinea corporis lesions

Answer 15

annular, erythamatous, scaly pruritic border with clear centre

Question 16

How does Cypoterone acetate work?

Answer 16

Inhibits 17-alpha - hydroxylase

Question 17

How is erythema multiform characterised?

Answer 17

target lesion

Question 18

What is. erythema multiform pmost commonly precipitated from?

Answer 18

Herpes simplex virus
Mycoplasma pneumonia

Question 19

Describe target lesions

Answer 19

concentric rings, colour variation, symmetrical

Question 20

Name the two layers of the skin

Answer 20

Epidermis
Dermis

Question 21

Epidermal development

Answer 21

Surface ectoderm covers the developing embryo (single-layered epithelium)

Proliferated to surface epithelium, periderm

Question 22

When does keratinisation occur?

Answer 22

19 weeks - skin becomes impermeable

Question 23

Where are melanocytes derived from

Answer 23

ectoderm

they migrate from neural tube to epidermis
Non-functioning until 2nd trimester

Question 24

Pathophysiology of congenital dermal melanocytosis

Answer 24

Melanocytes fail to reach their proper location in epidermis and entrapped in dermis at time of birth

Birthmark slowly resolves with time

Question 25

Dermal development

Answer 25

Face and anterior scalp are dried from neural crest ectoderm Extremities and trunk from mesoderm

Question 26

When are dermal. fibroblasts developed by?

Answer 26

6- 8 weeks

Question 27

When do the fibroblast synthesise collagens and micro fibrillar components

Answer 27

12- 15 weeks

Question 28

What are the layers of the epidermis

Answer 28

stratum corner - outer layer of dead cells and keratin stratum lucid (only on palm and soles) Stratum granulosum Stratum spinosum Stratum basale

Question 29

What type of cells is epidermis

Answer 29

stratified squamous epithelium

Question 30

Name the cell types of epidermis

Answer 30

Kertainocytes Melanocytes Merkel cells Langerhans cells