Dermatology - Common Skin Disorders & Skin Infections Flashcards
What is the structure of the skin?
Epidermis
Dermis : contains blood vessels, veins, loose connective tissues, nerves
subcutaneous layer
look at slide 4
What is the histology of human skin?
- Stratum corneum
- Stratum Granulosum
- Basal layer
4.Dermal papilla
5.Dermis
look at slide 5
What is the skin adnexa?
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
What else does the skin have apart from the adnexa?
Complex vascular network which allows the skin to shunt blood to the surface to dissipate heat or retain blood flow deeper in the dermis
What are the functions of the skin?
Protection from the environment (chemical, thermal, physical, UV injury)
Thermoregulation
Neuroreceptor (external stimuli)
Antigen processing (Langerhans cells)
Synthesis of vitamin D
Cosmetic
History taking in a patient with a skin disorder:
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
What parts do you have to remember to examine when doing a skin inspection?
‘Hidden sites’ e.g. scalp, nails, umbilicus, natal cleft
Mucous membranes: oral mucosa, eyes, nasopharynx and sometimes genitalia
What do you note down when examining a rash of some sort?
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
What is a macule/patch?
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
What is a plaque?
A slightly raised flat topped lesion >1cm diameter
look at slide 12
What is a papule?
A circumscribed palpable elevation <1cm
These can be itchy & may be associated with lacy white lines or ulcers orally.
look at slide 13
What might itchy flat-topped papules be?
Lichen planus
What is a nodule?
A palpable elevation >1cm
It’s black/brown
look at slide 14
What is scaling?
Peeling of the stratum corneum/superficial epidermis
Due to dryness of the skin, itchy and dehydrated.
slide 15
What is a vesicle?
A blister <0.5cm diameter
Itchy
slide 16
What is lichenification & excoriation?
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
What is a bulla?
A blister >0.5cm in diameter (intra-orally)
slide 18
What is an ulcer?
Full thickness loss of epidermis
look at slide 19
what is a scar?
Permanent change in skin surface/texture
slide 20
What tests may you need to carry out in order to clarify or confirm a skin diagnosis?
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
If a patient is unwell & either infected or in need of systemic therapy, what blood investigations may be required?
Haematology: FBC, ESR
Biochemistry: U+E, LFT, glucose, CRP
Immunology: ANA, DNA, organ specific antibodies
Virology: herpes simplex serology
What are the management options for skin conditions?
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
What is eczema?
A pruritic inflammatory condition associated with dryness & erythema of skin
Scratching results in excoriation & lichenificatio
What are some sub-types of eczema?
Atopic/flexural
Discoid
Varicose - poor circulation
Seborrhoeic
Lichen simplex
look at slide 25
What can eczema be secondarily infected with?
- Staphylococcus aureus (impetiginised eczema)- there’s yellow crust & weeping
- Herpes simplex (eczema herpeticum)- monomorphic lesions
slide 26
What 2 situations might dermatitis/eczema be secondary to?
Irritant contact
Allergic contact dermatitis
slide 27
How do you manage patients with eczema?
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
What are the types of psoriasis?
Psoriasis vulgaris (chronic plaque psoriasis)
Guttate
Erythrodermic
Pustular
slide 29
how is psoriasis characterised?
Psoriasis vulgaris = chronic plaque psoriasis Well-defined salmon pink plaques with silvery scale
What parts of the body are commonly affected in psoriasis?
The scalp & hairline are frequently affected
Nail pitting & subungual hyperkeratosis is sometimes present
slide 30
What are the clinical features of psoriasis?
2% prevalence. Strong family history
Symmetrical well-defined red plaques with thick silvery scale
Elbows & knees common sites
Lasts for many years
What does guttate psoriasis look like?
Raindrop size lesions often follows a streptococcal throat infection.
slide 32
What are the treatments for psoriasis?
Emollients/bath oils
Vitamin D analogues e.g. calcipotriol
Tar preparations
Topical steroids
Dithranol
UVB, PUVA
Systemic- acitretin, methotrexate, cyclosporin, biologics
What are the clinical features & variants of lichen planus?
-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
Show some examples of what the different variants of lichen planus look like.
Results in scarring in some sites
look at slide 36
How does oral lichen planus manifest?
Reticular lichen planus
Desquamative gingivitis - bright red, swollen, painful gums
look at slide 38
How do you treat lichen planus?
Topical: emollients, topical steroids (check candida count orally)
Systemic: prednisolone, azathioprine/mycophenolate, methotrexate
What can pruritus be associated with?
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
what is pruritus
itching
what can Bacterial infections Staphylococcus aureus/ streptococcal infections cause
Impetigo
cellulitis
paronychia
look at slide 44
