Dermatology - Common Skin Disorders & Skin Infections

Question 1

What is the structure of the skin?

Answer 1

Epidermis

Dermis : contains blood vessels, veins, loose connective tissues, nerves

subcutaneous layer

look at slide 4

Question 2

What is the histology of human skin?

Answer 2

1. Stratum corneum
2. Stratum Granulosum
3. Basal layer
   4.Dermal papilla
   5.Dermis
   look at slide 5

Question 3

What is the skin adnexa?

Answer 3

Skin appendages:

anatomical skin-associated structures that serve a particular function including sensation, contractility, lubrication & heat loss in animals e.g. hair, sebaceous/sweat glands

Question 4

What else does the skin have apart from the adnexa?

Answer 4

Complex vascular network which allows the skin to shunt blood to the surface to dissipate heat or retain blood flow deeper in the dermis

Question 5

What are the functions of the skin?

Answer 5

Protection from the environment (chemical, thermal, physical, UV injury)

Thermoregulation

Neuroreceptor (external stimuli)

Antigen processing (Langerhans cells)

Synthesis of vitamin D

Cosmetic

Question 6

History taking in a patient with a skin disorder:

Answer 6

Age, sex occupation
History of presenting complaint
- symptoms/ initial site/ subsequent involvement
Relevant systems review
Current/past treatment
Past medical history
Family history
Drug history
Allergies

Question 7

What parts do you have to remember to examine when doing a skin inspection?

Answer 7

‘Hidden sites’ e.g. scalp, nails, umbilicus, natal cleft

Mucous membranes: oral mucosa, eyes, nasopharynx and sometimes genitalia

Question 8

What do you note down when examining a rash of some sort?

Answer 8

Site: localised, generalised, distribution, skin/mucous membranes

Morphology: mono (all the same) /polymorphic (different e.g some might have a blister/erosion, scarring)

Background skin: normal/erythema

Question 9

What is a macule/patch?

Answer 9

Flat lesions on skin which are visible as circumscribed areas but are not palpable (able to be touched or felt)

Macule<1cm
Patch>1cm

look at slide 11

Question 10

What is a plaque?

Answer 10

A slightly raised flat topped lesion >1cm diameter

look at slide 12

Question 11

What is a papule?

Answer 11

A circumscribed palpable elevation <1cm

These can be itchy & may be associated with lacy white lines or ulcers orally.

look at slide 13

Question 12

What might itchy flat-topped papules be?

Answer 12

Lichen planus

Question 13

What is a nodule?

Answer 13

A palpable elevation >1cm

It’s black/brown

look at slide 14

Question 14

What is scaling?

Answer 14

Peeling of the stratum corneum/superficial epidermis

Due to dryness of the skin, itchy and dehydrated.

slide 15

Question 15

What is a vesicle?

Answer 15

A blister <0.5cm diameter

Itchy
slide 16

Question 16

What is lichenification & excoriation?

Answer 16

Lichenification: thickening from scratching is visible here in the popliteal fossa

Excoriation: a shallow breach in the surface from scratching often with a haemorrhagic crust

slide 17

Question 17

What is a bulla?

Answer 17

A blister >0.5cm in diameter (intra-orally)

slide 18

Question 18

What is an ulcer?

Answer 18

Full thickness loss of epidermis

look at slide 19

Question 19

what is a scar?

Answer 19

Permanent change in skin surface/texture

slide 20

Question 20

What tests may you need to carry out in order to clarify or confirm a skin diagnosis?

Answer 20

Skin swabs/scraping: bacteriology, virology, mycology

Skin biopsy: histology, culture, immunofluorescence

Patch tests: undertaken if contact allergy is suspected

Photo-tests: to investigate a possible sensitivity to UV

Question 21

If a patient is unwell & either infected or in need of systemic therapy, what blood investigations may be required?

Answer 21

Haematology: FBC, ESR

Biochemistry: U+E, LFT, glucose, CRP

Immunology: ANA, DNA, organ specific antibodies

Virology: herpes simplex serology

Question 22

What are the management options for skin conditions?

Answer 22

General measures:
assess need for admission
e.g. fluid balance, thermoregulation nutrition, infection control

Topical:
infection - antibacterial agents, candida corticosteroids creams, mouthwash

Systemic:
prednisolone +/- steroid sparing agents antibiotics

Referral:
Ophthalmology, Dermatology, ENT

Question 23

What is eczema?

Answer 23

A pruritic inflammatory condition associated with dryness & erythema of skin

Scratching results in excoriation & lichenificatio

Question 24

What are some sub-types of eczema?

Answer 24

Atopic/flexural
Discoid
Varicose - poor circulation
Seborrhoeic
Lichen simplex

look at slide 25

Question 25

What can eczema be secondarily infected with?

Answer 25

1. Staphylococcus aureus (impetiginised eczema)- there’s yellow crust & weeping
2. Herpes simplex (eczema herpeticum)- monomorphic lesions

slide 26

Question 26

What 2 situations might dermatitis/eczema be secondary to?

Answer 26

Irritant contact
Allergic contact dermatitis

slide 27

Question 27

How do you manage patients with eczema?

Answer 27

Avoid soap, shower gel & contact with irritants such as domestic cleaning agents

Advise use of: emollients, topical steroids, oral antibiotics, antihistamines, wet wraps, acyclovir if suspect herpes simplex

Question 28

What are the types of psoriasis?

Answer 28

Psoriasis vulgaris (chronic plaque psoriasis)
Guttate
Erythrodermic
Pustular

slide 29

Question 29

how is psoriasis characterised?

Answer 29

Psoriasis vulgaris = chronic plaque psoriasis Well-defined salmon pink plaques with silvery scale

Question 30

What parts of the body are commonly affected in psoriasis?

Answer 30

The scalp & hairline are frequently affected
Nail pitting & subungual hyperkeratosis is sometimes present

slide 30

Question 31

What are the clinical features of psoriasis?

Answer 31

2% prevalence. Strong family history

Symmetrical well-defined red plaques with thick silvery scale

Elbows & knees common sites

Lasts for many years

Question 32

What does guttate psoriasis look like?

Answer 32

Raindrop size lesions often follows a streptococcal throat infection.

slide 32

Question 33

What are the treatments for psoriasis?

Answer 33

Emollients/bath oils
Vitamin D analogues e.g. calcipotriol
Tar preparations
Topical steroids
Dithranol
UVB, PUVA
Systemic- acitretin, methotrexate, cyclosporin, biologics

Question 34

What are the clinical features & variants of lichen planus?

Answer 34

-Unknown aetiology 1-2% population
-Onset 30-60yrs
-Flat-topped violaceous papules on skin
-Predilection for flexor surfaces and lower back

Clinical variants:
Hypertrophic annular plantar
Oral – several sub-types Lip
genital
scalp – lichen planopilaris

Question 35

Show some examples of what the different variants of lichen planus look like.

Answer 35

Results in scarring in some sites

look at slide 36

Question 36

How does oral lichen planus manifest?

Answer 36

Reticular lichen planus

Desquamative gingivitis - bright red, swollen, painful gums

look at slide 38

Question 37

How do you treat lichen planus?

Answer 37

Topical: emollients, topical steroids (check candida count orally)

Systemic: prednisolone, azathioprine/mycophenolate, methotrexate

Question 38

What can pruritus be associated with?

Answer 38

Xerosis - dry skin
Dietary - iron deficiency anaemia
Endocrine - thyroid disorders, diabetes mellitus
Inflammatory - eczema, urticaria
Autoimmune - lichen planus, dermatitis herpetiformis
Infective - chicken pox
Infestation - scabies
Parasitic - cutaneous larva migrans
Neoplastic - cutaneous T cell lymphoma, myeloproliferative, lymphoma

Question 39

what is pruritus

Answer 39

itching

Question 40

what can Bacterial infections Staphylococcus aureus/ streptococcal infections cause

Answer 40

Impetigo
cellulitis
paronychia

look at slide 44