Intro to general dermatology

Question 1

• Describe the structure and functions of normal skin
• Describe the principles of wound healing
• Relate knowledge of normal skin structure and function to alterations that occur in the context of skin disease
• Apply knowledge of pathophysiology when discussing the processes of diagnosis, investigation and treatment of skin disease

Answer 1

.

Question 2

Skin contains what adnexal structures

Answer 2

Hair
Nails
Glands
Sensory structures

Question 3

3 basic layers of skin (superficial to deep)

Answer 3

Epidermis
Dermis
Hypodermis (subcutaenous tissue)

Question 4

Function of subcutaneous tissue layer of skin

Answer 4

Fat energy store
Insulation
Contains fibrous bands that anchor dermis to muscle and bone

Question 5

Dermis consists of

Answer 5

collagen and elastin matrix
fibroblasts (synthesise the extracellular matrix and collagen)
dermal dendritic cells/macrophages

Question 6

Epidermis consists of what 3 cell types

+ which is most abundant

Answer 6

Keratinocytes (skin cells) - majority
Melanocytes (produce skin pigment)
Langerhans cells (immune cells)

Question 7

Function of langerhans cells in the epidermis

Answer 7

process antigens and migrate to lymph nodes to induce an immune response

Question 8

Which layer of skin is avascular

Answer 8

epidermis

Question 9

How are new skin cells formed and shed

Answer 9

Formed in the lower layers of the epidermis

• travel upwards and when they enter the stratum corneum (most superficial layer of epidermis), are shed off
• occurs in around a month

Question 10

What anchors the epidermis to the dermis

Answer 10

Basement membrane and hemidesmosomes

Question 11

Epidermis is subdivided in what 5 layers

Answer 11

Stratum corneum
Stratum lucidum
Stratum granulosum
Straum spinosum
Stratum basale

Question 12

What is the stratum corneum

Answer 12

Most superficial layer of the epidermis (i.e. most superficial layer of skin) contains dead keratinocyte (skin cells) that are continuously shed

Question 13

Epidermis regenerates every month but this happens quicker in what skin diseases

Answer 13

psoriasis

Question 14

Name the white part of the nail at the bottom

Answer 14

lunula

Question 15

Name the 3 stages of the hair cycle + describe them

Answer 15

Anagen - active growing phase
Catagen - few weeks where growth stops/follicles shrink
Telogen - resting phase for few months

Question 16

Functions of skin (6)

Answer 16

Thermoregulation
Physical barrier
Immune role - innate + adaptive
Sensation - temp, touch, pain, pressure
Vitamin D synthesis
Sociosexual communication - physical appearance, self identity

Question 17

Skin is a physical barrier against (4)

Answer 17

Trauma
Chemicals
Microbes - infection
UV light/radiation

Question 18

How does skin synthesise vitamin D

Answer 18

UV light converts 7-dehydrocholesterol to cholecalciferol

Question 19

External causes of skin disease (5)

Answer 19

Temp - ++ hot or cold
UV radiation (photosensitivity)
Chemical (allergen or irritant)
Infection
Trauma

Question 20

Internal causes of skin disease (4)

Answer 20

Systemic diease, e.g. autoimmune
Genetics
Drug induced
Infection

Question 21

Drugs that induce photosensitivity of skin (5)

Answer 21

Antibiotics, e.g. tetracycline, ciprofloxacin
NSAIDs, e.g. ibruprofen
Diuretics, e.g. furosemide
Retinoids
Antifungals

Question 22

What skin conditions can the cold cause

Answer 22

Frostbite
Skin necrosis
Cold urticaria

Question 23

What is urticaria

Answer 23

aka hives - swollen, pale red plaques (i.e. big raised papule)

Question 24

What is bullous pemphigoid caused by

Answer 24

Autoimmune reaction against skin leading to bullae (large serous fluid filled lesion) and plaques (raised red areas)

Question 25

Define macule v patch

Answer 25

Macule - small inpalpable (i.e. FLAT) circumscribed area of altered colour but normal texture, e.g. freckle Patch - large version of macule

Question 26

Define papule v plaque

Answer 26

Papule - small raised palpable alteration, e.g. wart, insect bite Plaque - large version of papule; often due to inidividual papule coalescing, e.g. psoriasis

Question 27

Define vesicle v bulla

Answer 27

Vesicle - small serous filled lesion Bulla - large serous fluid filled lesion

Question 28

Define pustule v abscess

Answer 28

Pustule - small pus filled lesion Abscess - large pus filled lesion

Question 29

Define erosion v ulcer

Answer 29

Erosion - loss of epidermis | Ulcer - loss epidermis and dermis

Question 30

Define scaling of the skin

Answer 30

altered epidermis and the scale may remain adherent or desquamate (peel off in the form of scales)

Question 31

Define exfoliation of the skin

Answer 31

total or continuous shedding of the superficial epidermis

Question 32

Epidermal damage usually heals without .., but any deeper excoriation or ulceration may heal with ...

Answer 32

scarring

Question 33

Erythema (redness of skin) is due to

Answer 33

inflammatory vascular dilation (increased blood flow in superficial capillaries)

Question 34

Telangiectasia describes...

Answer 34

permanently dilated blood vessels that fade with pressure.

Question 35

How is a freckle formed

Answer 35

No increase in the number of melanocytes but the melanosomes (collections of melanin) they produce are long and rod-shaped, like those found generally in the dark skinned

Question 36

How may distribution of a skin disease help diagnosis

Answer 36

sometimes the localisation of multiple lesions in certain regions helps diagnosis, as skin diseases tend to have characteristic distributions

Question 37

What the distribution of a skin disease refer to

Answer 37

how the skin lesions are scattered/spread out

Question 38

Cutaneous signs are seen in what diseases

Answer 38

``` Erythema Nodosum Sarcoidosis Vasculitis Malignancy Auto-immune conditions ```

Question 39

Investigations of a suspected bacterial skin infection (2)

Answer 39

Charcoal swab + MC+S (microscopy, culture + sensitivities) of the swab

Question 40

Investigations of a suspected viral skin infection (2)

Answer 40

Viral swab for PCR | If systemic illness --> throat swab

Question 41

Investigations of a suspected fungal skin infection (3)

Answer 41

Fungal cultures of - Skin scraping - Nail clipping - Hair sample

Question 42

Melanocytes produce what

Answer 42

melanosomes (collections of melanin)

Question 43

What is a lentigo + process behind this

Answer 43

small brown macule increased number of melanocytes at the dermo- epidermal junction