Introduction to dermatology Flashcards
What is the largest organ in the body?
skin
List some accessory structures of the skin
hair, nails, sensory structures
Name the 2 layers of the skin
epidermis and dermis
3 cell types found in the epidermis
keratinocytes (most)
Langerhans
melanocytes
What composes the dermis?
collagen and elastin matrix with mucopolysaccharide gel
fibroblasts, sebaceous and sweat glands, hair follicles, macrophages, dermal dendritic cells
What is the sub cutis? function?
fat energy store
insulation and anchor skin to fascia
Function of melanocytes
make melanosomes (melanin) which is excreted and phagocytosed into keratinocytes to protect from UV exposure
Role of Langerhans cells
Process antigens and migrate to LN to induce an immune response
Name the 5 layers of the epidermis
stratum corneum stratum lucidium stratum granulosum stratum spinosum stratum basale
What layer of epidermis has stem cells and the effect of this?
stratum basale
regenerative properties of the skin
What layer of epidermis do cells become dead?
granulosum
Functions of nail
protection
fine sensory and motor tasks
Nail matrix
tissue the nail protects
What part of the nail prevents the matric from becoming infected?
cuticle
3 phases of hair cycles
anagen
catagen
telogen
What hair phase is active?
anagen
What hair phase is the resting phase?
telogen
6 functions of the skin
thermoregulation barrier interpersonal communication skin immune system vitamin D synthesis sensation
5 D’s of why skin disease is important
disfigurement discomfort disability depression death
External causes of skin disease
temperature chemical infection trauma UV
Internal causes of skin disease
drugs
genetics
infection
systemic disease
What is the main cause of photosensitivity?
medication
reactive to UVA/B and visible light
exposed sites affected
Main clue with photosensitivity
areas under chin and behind ear unaffected
Cold urticaria
skin reaction to cold due to mast cell degranulation
dermatitis artefacta
burn, aerosol can, suction blister
self inflicted
bullous pemphigoid
blisters at dermal-epidermal junction due to anti hemidesmosome antibodies
Morphology
appearance of skin lesions
What size does small mean?
less than 5mm
macule
small circumscribed area
patch
large circumscribed area
papule
small raised area
Plaque
large raised area
vesicle
small fluid filled
bulla
large fluid filled
pustule
small pus filled
abscess
large pus filled
erosion
affecting epidermis - loss
ulcer
loss of epidermis and dermis
What is the difference between a macule/patch and normal skin?
colour ONLY
What is a small and large intradermal haemorrhage called?
petechiae
purpura
What can distribution of skin lesions tell us?
help with diagnosis eg solitary, symmetrical, multiple, general
What is eruptive xanthoma indicative of?
hyperlipidaemia
What is acanthosis nigracans linked to?
type 2 DM, obesity, malignancy
How are cutaneous signs helpful in diagnosing?
can tell us about systemic illnesses and many other conditions eg malignancy, auto-immune, sarcoidosis
How do we investigate bacterial dermatology?
charcoal swab
swab exudate, ulcers etc (do blood test if none)
microscopy, culture and sensitivity
Viral investigations in dermatology
viral swab for PCR
swab vesicle/bulla if vesicular eruption
If a viral infection is systemic how do we investigate in dermatology?
throat swab
Fungal investigations
nail clippings
hair sample
skin clipping
Skin biopsy uses
punch biopsy - 5mm radius
eczema, psoriasis, malignancy etc
