Skin

Question 1

Layers of the epidermis

Answer 1

'Come Let's Get Some Beers'
Stratum corneum
Stratum lucidum 
Stratum granulosum
Stratum spinosum
Stratum basale

Question 2

In which layer of the epidermis are melanocytes found?

Answer 2

Stratum basale

Question 3

Name the 4 inflammatory reaction patterns in the epidermis

Answer 3

Vesiculobullous, spongiotic, lichenoid, psoriasiform,

Question 4

Name the 2 inflammatory reaction patterns in the dermis

Answer 4

Vasculitic, granulomatous

Question 5

Name 3 conditions with a vesiculobullous reaction pattern

Answer 5

Bullous pemphigoid, pemphigus vulgaris, pemphigus foliaceus

Question 6

Presentation of bullous pemphigoid

Answer 6

Elderly, autoimmune, high mortality rate (10-20%)
Sub-epidermal blisters as epidermis lifts off dermis
Flexor surfaces, tense bullae

Question 7

Pathophysiology of bullous pemphigoid

Answer 7

IgG and C3 attack the basement membrane
• Detected by immunofluorescence
• IgG anti-hemidesmosome
Eosinophils recruited to release elastase
Elastase damages the anchoring proteins
Fluid fills up gap between BM and epithelium

Question 8

Presentation of pemphigus vulgaris

Answer 8

Deep

Flaccid blisters, rupture easily

Question 9

Where is affected in bullous pemphigoid?

Answer 9

Dermo-epidermal junction affected

Question 10

Where is affected in pemphigus vulgaris?

Answer 10

Epiderma-epidermal junction affected (inter-epidermal)

Question 11

Pathophysiology of pemphigus vulgaris

Answer 11

IgG attacks between the keratin layers (acantholysis) i.e. loss of intracellular connections
Common for many conditions; need immunofluorescence to confirm

Question 12

Presentation of pemphigus foliaceus

Answer 12

Fairly superficial

Top layer is very thin so never blisters

Question 13

Pathophysiology of pemphigus foliaceus

Answer 13

IgG-mediated – outer layer of stratum corneum shears off

Diagnose with immunofluorescence

Question 14

Name 2 conditions with a spongiotic reaction pattern

Answer 14

Discoid eczema, contact dermatitis

Question 15

Presentation of discoid eczema

Answer 15

Flexor surfaces

Very itchy; plaques form

Question 16

Presentation of contact dermatitis

Answer 16

Red, sore, itchy
Itchy; latex and nickel
Itchy –> hyperparakeratosis (thickening)
Epidermis gets thicker –> lichenification

Question 17

Pathophysiology of eczema

Answer 17

Epidermis gets thicker
Eczema is spongiotic because there is oedema in between the keratinocytes (intercellular oedema)
T cell mediated and eosinophils are recruited
A differential for an eczematous reaction pattern is a drug reaction

Question 18

Name a condition with a psoriasiform reaction pattern

Answer 18

Plaque psoriasis

Question 19

Presentation of plaque psoriasis

Answer 19

Silver plaques on extensor surfaces

Question 20

Pathophysiology of psoriasis

Answer 20

Normal keratinocyte turnover time = 56 days
Psoriasis keratinocyte turnover time = 7 days
Rapid turnover –> epidermis thicker
A layer of parakeratosis forms at the top
Stratum granulosum disappears as not enough time to form it; and dilated vessels form
Munro’s microabscesses form, made up from recruitment of neutrophils

Question 21

Name 2 conditions with a lichenoid reaction pattern

Answer 21

Lichen planus, erythema multiforme

Question 22

Presentation of lichen planus

Answer 22

Itchy
Papules and plaques of purplish-red colour on the wrists and arms
In mouth it presents as white lines (Wickham striae)

Question 23

Pathophysiology of lichen planus

Answer 23

T cell-mediated

T-lymphocytes have destroyed bottom keratinocytes
Creates band-like inflammation
Cannot see where dermis finished, and epidermis starts

Question 24

Name a condition with a vasculitic reaction pattern

Answer 24

Pyoderma gangrenosum

Question 25

Presentation of pyoderma gangrenosum

Answer 25

Non-healing ulcer Not actually gangrenous! Often first presentation of a systemic disease e.g. colitis, hepatitis, leukaemia

Question 26

Presentation of seborrhoeic keratosis

Answer 26

"Cauliflower”, pigmented, gets caught on clothing (and taken off) Stuck-on appearance, harmless and benign

Question 27

Pathophysiology of seborrhoeic keratosis

Answer 27

Lots of growth and ordered proliferation Ordered and benign growth “Horn cysts” – epidermis entrapping keratin

Question 28

Describe a sebaceous cyst

Answer 28

Transluminates, central punctum, circumscribed, hot | Squamous cell lining surrounding the cyst

Question 29

Presentation of a basal cell carcinoma

Answer 29

Rolled, pearly-edge, central ulcer, telangiectasia | “Rodent ulcer” as it burrows away

Question 30

Characteristics of BCC

Answer 30

Benign but can disfigure Locally aggressive Hardly ever metastasises Occurs in sun-exposed areas

Question 31

Common mutation in BCC

Answer 31

PTCH mutation is a somatic mutation commonly seen in BCC (usually due to UV exposure but can be inherited)

Question 32

Histopathology of BCC

Answer 32

Dysplastic change Cancer from keratinocytes at bottom of epidermis Cannot break through the BM --> cannot metastasise

Question 33

What is Bowen's disease?

Answer 33

Squamous cell carcinoma in situ [i.e. pre-cancerous] Dysplasia Keratinocytes become more pleiomorphic and larger with mitotic figures Bowen’s disease name changes depending on location (i.e. anal vs. cervix)

Question 34

What is actinic keratosis aka solar keratosis?

Answer 34

Pre-malignant disease (dysplasia) Sun damage Thickening of epidermis as proliferating more than usual Rough and scaly appearance

Question 35

Name 4 benign melanocytic conditions

Answer 35

(1) Café-au-lait spots = a form of melanocytic naevus (2) Junctional nevus = melanocytes nest in the epidermis [pictured] o Flat and coloured o Normally, melanocytes sit in the basal layer of the epidermis o Melanocytes can, however, physiologically exist in the dermis o As you age, melanocytes usually drop into the dermis (3) Compound nevus = nests in epidermis and dermis o Raised area o Surround by flat pigmented area (4) Intradermal naevus = nests in the dermis o Raised area o Skin-coloured or pigmented

Question 36

Criteria for assessing melanoma

Answer 36

``` ABCDE Asymmetry Border (irregular) Colour Diameter Evolution ```

Question 37

Describe pagetoid spread of melanoma

Answer 37

The junctional melanocytes are not normally maturing and dropping out of the dermis – they are moving up through the dermis instead = “Pagetoid spread” this is NOT normal

Question 38

Name and describe the staging system for melanoma

Answer 38

Staged by “Breslow Thickness” measured from granular layer to bottom of bottommost normal melanocyte >4mm = BAD

Question 39

Name a common mutation in melanoma

Answer 39

BRAF v600e