10 Dermatology

Question 1

Skin cells responsible for protecting against UV damage (2)

Answer 1

Keratinocytes (contain DNA) and melanocytes (cap over the top to protect DNA)

Question 2

Chronic UV exposure effects skin

Answer 2

Wrinkles, premature ageing, loss of elasticity, fragility
Abnormal pigmentation
Haemorrhage of small blood vessels

Question 3

Vitamin D deficiency increased risk (4)

Answer 3

CVD
Cancers
Autoimmune - MS
Infectious disease

Question 4

How is vitamin D absorbed by skin?

Answer 4

UVB photos absorbed (by 7-dehydrocholesterol) by skin and converted or previtD3 -> converted to active vitD3 in plasma membrane

Question 5

Function and each cutaneous receptor:
Free nerve endings
Merckel's discs
Meissner's corpuscles
Ruffini corpuscles
Pacinian corpuscles

Answer 5

> Free nerve endings - pain and temperature
Merckel’s discs - light touch
Meissner’s corpuscles - gentle pressure (shape and size)
Ruffini corpuscles - deep pressure and stretch
Pacinian corpuscles - deep touch, deformation, joint position/proprioception

Question 6

Definition of:
Macule
Papule
Pustule
Plaque
Vesicle
Bulla
Erythema
Ulceration

Answer 6

Macule - flat change in colour
Papule - raised lump
Pustule - raised lump filled with pus
Plaque - rough and raised
Vesicle - small blister
Bulla - large blisters
Erythema - red rash
Ulceration - removal of epidermis

Question 7

Features required for a clinical diagnosis of acne (3)

Answer 7

Papules
Pustules
Comedones

Question 8

Acne grading system

Answer 8

Lee grading system 1-12

Question 9

Treatment for acne (5):

Answer 9

Unplugging: topical retinoids/ benzoyl peroxide

Reducing bacteria: topical Abs (erythromycin/ clarythromycin), oral Abs (erythromycin/tetracycline), often in combo with benzoyl peroxide (Abx resistance)

Reducing sebum production: anti-androgen hormone therapy = OCP/ Dianette

Dietary modification - limited evidence

Oral isotretinoin - oral retinoid (vic A) which reduces plugging, bacteria and sebum production

Question 10

Oral isotretanoin:
Dose
Side effects

Answer 10

Dose = 1mg/kg

Side effects: dry lips/ skin, nosebleeds, myalgia, liver problems, hyperlipidemia, mood disturbance, teratogenicity

Question 11

Side effects of acne medications - oral and topical

Answer 11

Oral: GI upset (tetracycline)
Topical: burning/bleaching/irritation/peeling (benzoyl peroxide)

Question 12

Genetic and immune components of atopic eczema

Answer 12

Genetic: inherited fillagrin gene defect (binds keratin in epidermis) causes defect of barrier - decreased antimicrobial & increased permeability

Immune: type 1 hypersensitivity - alongside asthma, hay fever, allergic rhinitis, conjuctivitis

Question 13

Complications of atopic eczema

Answer 13

> 2y infection - bacterial (staph A) viral (warts, molluscum, herpeticum)
growth reduction (lack of sleep)
psychological impact

Question 14

Diagnostic criteria and main treatment for atopic eczema

Answer 14

ITCHY inflammatory skin condition

Treatment:
>Emollient, topical steroids, antihistamines (itch), bandage (scratch)
>Education of patient/parent and avoidance of exacerbation

> antibiotics/antivirals (acyclovir) - 2y infection
systemic immunosuppressant drugs - cyclosporin/methotrexate/biologics (dupilumab)

Question 15

Describe 2 types of contact dermatitis

Answer 15

irritant - direct noxious effect on skin

allergic - type 4, body builds up hypersensitivity to substance > heightened 2nd response

Question 16

Describe suborrhoeic dermatitis and treatment
and
Varicose dermatitis and treatment

Answer 16

Suborrhoeic: Chronic scaly affecting face/ scalp/ brows/ upper chest - due to Pityrosporum Ovale yeast
Tx = anti-yeast shampoo,
antimicrobial/steroid face cream, moisturiser
systemic antifungal (rare), UV

Varicose: venous insufficiency in return > inc hydrostatic pressure > fluid leaks out into lower legs > skin stretched > inflammation and dermatitis, blood leaks out (brown haemosiderin staining), scratching causes ulceration
Tx = emollient, topical steroid, compression bandage/stocking, venous surgery

Question 17

Describe pathogenesis of psoriasis

Answer 17

Abnormal accumulation of T cells which:

1) release inflammatory cytokines (TNF/IL/IFN)
2) increase keratinocyte turnover (scales)

Question 18

Types of psoriasis (6)

Answer 18

1) plaque - extensor, symmetrical, salmon pink scaly plaque, nails affected
2) guttate - younger fit people, fast onset - strep A trigger
3) pustular - inflammatory with tiny pustules, may be 2y
4) erythrodermic - peeling of whole body
5) palmar/plantar pustulosis - smokers
6) Koebner phenomenon - scars and trauma sites

Question 19

Scoring systems for psoriasis (3)

Answer 19

DLQI - disease life quality index
PASI - psoriasis area severity index
PEST - rheumatology related

Question 20

Treatment for psoriasis

and 2 things that should NOT be given

Answer 20

1) Topical - moisturiser, steroids, decrease keratinocyte production (vitamin D analogue, coal tar, dithranol)
2) UV
3) Oral - immunosuppressants (methotrexate/ cyclosporin), biologics (inflixumab/adilumimab antiTNF), retinoids (acitretin)

Question 21

Treatment for bacterial infections releasing toxins

Answer 21

Clindamycin - attacks at level of protein synthesis

Question 22

Classification of cellulitis

Answer 22

Enron classification
1
a
b
2
3
4