Skin Flashcards
What is the layers of the skin (biggest organ of the body)
Epidermis
Dermis
Hypodermis = subcutaneous tissue which anchos skin to fascia (useful in insulation)
Skin appendages = derived from skin cells
- Hair
- Nails
- Sebaceous glands
- Sweat glands
What is the epidermis made up of and what pathology can affect
Striatum cornea (thick top layer made up of keratin)
- Thickest in palms and soles
- Thin at eyelids
Keratonocytes - produce keratin
Melanocytes - produce melanin
Lagerhan’s - immune (process antigen and migrate to LN)
Average turnover = 30 days
Pathology
- Change in turnover e.g. psoriasis
- Change in surface or loss of epidermis e.g. scales / ulcer
- Change in pigmentation
What is the dermis made up of
Collagen = mainly Fibroblasts synthesis elastin Dendiritc cells for immune Nerves + blood vessels Adrenal structures - hair / glands / sensory
Pathology
- Change in contour / loss of dermis
- Disorder of skin appendages - hair / acne (Sebaceous gland)
- Change lymphatics / blood vessel - erythema, urticaria, purpura
What are nails made up of
Nail plate (hard keratin) which arises from nail matrix at posterior nail fold and rests on nail bed Nail bed contains capillaries which give colour
What is the stages of the hair cycle and types of hair
Lanugo - fine long hair in fetus
Vellus - fine short hair on all areas
Terminal - coarse long hair on scalp, eyebrows, eyelash and pubic
Hair shaft - keratinised tube
Hair bulb - actively dividing cells and melanocyte which gives pigment
Anagen = active growing Catagen = growth stops + follicle shrinks Telogen = resting phase
What are the functions of the skin
Thermoregulation - insulation / sweat / blood flow Immune system - innate and adaptive Barrier Sensation Synthesis of Vitamin D Personal communication
What causes skin disease
Photosensitivity - often medication
Temperature - frost bite / necrosis / cold urticaria
Trauma - dermatitis artefacts
Genetics - eczema / psoriasis / acne / neurofibroma
Autoimmune - bullous pemphigoid
Infection
Systemic
What is a macule
Small flat circumscribed area <5mm of altered colour
What is a patch
Larger flat area of altered colour >5mm
What is a papule
Small raised area <0.5cm
What is a plaque
Large raised area >0.5cm
What is a vesicle
Small fluid filled lesion <0.5cm
What is a bullae
Large fluid filled
What is a pustule
Small pus
What is an abscess
Large pus in dermis or subcutaneous tissue
What is wheal
Transient raised lesion due to localised oedema
What is an erosion
Superficial loss of epidermis
Heals without scarring
What is an ulcer
Loss of epidermis and denims
Heals with scarring
Why can skin regenerate
Has stem cells
What causes purpura in children
Thrombocyotpenia Meningococcal septicaemia - non-palpable ALL Congenital bleeding disorder ITP HSP - tend to be palpable NAI
What should you do to all children with new onset purpuric rash
Always admit to exclude life threatening
Ax prior to transfer to hospital as may be due to menigococcal septicaemia
Clotting screen and platelet to exclude coagulation disorder
What causes purpura in adults
Vasculitis Bone marrow failure ITP Drugs Nutrition
What can distribution of skin disease be
Localised
Generalised
Symmetrical
How can you investigate skin disease
Charcoal swab - bacterial and fungal Viral swab - vesicular eruption Skin scraping Nail scraping Dermoscopy
What do you send swab for
MC+S if charcoal
PCR if viral
Biopsy
Do you swab in cellulitis
No as will have pyrexia so need blood culture
What do you do if fungal suspect
Skin scraping
Nail clipping
Hair sample
Fungal culture
What is important in HPC of skin problem
Duration Initial appearance and evolution Symptoms - itch / pain Aggravating and relieving factors Previous and current Rx Recent contact / stress / travel Hx sunburn or sunbeds Skin type
What else is important
PMH - atopy / skin cancer FH - skin disease SH - occupation / do skin lesions improve DH QOL
How do you examine skin lesion
Inspect
Describe
Palpate
Systematic check
What do you look for on inspetion
Site and number of lesions
Pattern of distribution
How do you describe each individual lesion
SCAM Site Shape Colour Associated secondary change Morphlogy / Margin
What are you feeling for on palpation
Surface Consistency Mobility Tenderness Temperature
What systemic check do you do
Examine nail, scalp, hair and mucous membrane
General terms and meaning
Pruritus = itch Lesion = area altered skin Rash = eruption Naevus = localised malformation Comedone = plug in sebaceous follicle containing sebum and bacteria - If open = black head - If closed = white head
How do you describe distribution
Generalised = all over body
Extensive = widespread
Localised = one area of skin
Flexural = body folds
Extensor
Pressure area - sacrum / buttock / ankle / heel
Dermatome - supplied by single spinal nerve
Photosensitive - affects sun exposed area
Koebner - linear eruption arising at site of trauma
What can colour of lesions be
Erythema - redness due to inflammation which blanches
Purpura - red or purple due to bleeding which doesn’t blanch
- Petechiae = small pinpoint macules
- Ecchymoses = large bruising patches
Hypo-pigmentation
DE-pigmentation due to lack of melanin
Hyperpigmentation
How do you describe morphology/ structure of lesion
See above
How do you describe secondary morphology that arises from primary
See below
Excoriation
Loss of epidermis following trauma
Lichenification
Well-defined roughening of skin
Scaling
Flakes of stratum corneum
Crusting
Rough surface consisting of dried serum, blood, bacteria that has exude through eroded epidermis
Scar
New fibrous tissue post wound healing
- Atrophic = thinning
- Hypertrophic = within boundary
- Keloid - beyond boundary
Fissure
Epidermal linear split
Striae
Linear areas from purple-pink-white
Associated execessive steroid / growth / pregnancy
Hair terms
Alopecia = loss of hair Hirsutism = androgen dependent hair growth in female Hypertrichosis = non-adorgen dependent hair growth
Nail terms
Clubbing = Loss of angle between posterior nail fold and plate Koilonychia = spoon shaped depresion Onycholysis = separation of distal nail plate from nail bed Pitting = punctate depression
What is onycholysis associated with
Trauma
Psoriasis
Fungal
Hyperthyroid
What is pitting associated with
Psoriasis
Eczema
ALopeia acreana
What do sebaceous glands do
Produce sebum via hair follicles (pilosebaceous unit)
Lubricates and waterproofs skin
Become active at puberty
What do sweat glands do
Regulate body temperature
Innervated by sympathetic nervous
What is a cyst
Fluctuant swelling containing fluid or keratin
What is a comedone
Plugged sebaceous follicle
What bloods can be done in dermatology
Autoimmune screen Coag screen Monitoring systemic Rx Vit D ASOT Pruritus / alopecia screen
What is patch testing for
Exposure allergy
What is prick testing for
Systemic allergy
