DERM Flashcards
what type of epithelium is the epidermis made of
stratified cellular (squamous)
what is the dermis made up of
connective tissue
from which germ layer does the epidermis arise from
the ectoderm
from which germ layer does the dermis arise from
the mesoderm
where do melanocytes arise from
neural crest
what are the five layers of the skin
keratin layer granular layer prickle cell layer basal layer dermis
what structures can be found in the dermis
sebaceous glands
arector pilli muscles
hair follicles
where are melanocytes located
mainly in the basal layer of the epidermis
what are Blaschko’s lines
developmental growth pattern of the skin
which cell is most predominant in the epidermis
keratinocytes
other than keratinocytes, which cell types are present in the epidermis
melanocytes
langerhans cells
Merkel cells
what mechanism are in control of epidermal turnover
growth factors
cell death
hormones
what shape of cells are in the basal layer
small cuboidal cells
basal cells are highly metabolically active
true/false
true
what shape are cells in the prickle cell layer
larger, polyhedral cells
what sort of connections are present in the prickle cell layer
desmosomes
how many layers of cells make up the granular layer
2-3 layers
where are keratohyalin granules found and what do they contain
in the granular layer of the dermis
structural filaggrin and involucrin proteins
are there nuclei present in the granular layer
no
what sort of cells are found in the keratin later
corneocytes (overlapping non-nucleated cell remnants)
what is the function of the keratin layer?
tight waterproof barrier
where are mucosal membranes found
eyes, mouth, nose, GU and GI tracts
where are langerhans cells found
suprabasally
where are Merkel cells found
basal layer
what are melanocytes
pigment producing dendritic cells
what organelles are specific to melanocytes
melanosomes
what do melanocytes convert to create melanin
tyrosine
what are the two different types of melanin
eumelanin (brown or black)
phaeomelainin (red/yellow)
how are melanosomes transferred to adjacent keratinocytes
dendrites
what is vitiligo
an autoimmune disease resulting in loss of melanocytes
what is the function of langerhans cells
antigen presenting cells
‘racket organelle’ is associated with which cell type
langerhans cell
what is the function of Merkel cells
mechanoreceptors
what are the three phases of hair growth
anagen - growing
catagen - involuting
telogen - resting/shedding
which hormone influence hair growth
thyroxine
androgens
how long does the anagen phase last
3-7 years
how long does the catagen phase last
3-4 weeks
what is telogen effluvium
hair follicles synchronise their telogen phase around 3 months after a stress on the body (infection, childbirth)
what is hirsutism
male pattern hair growth in a female
what causes virilisation
excess androgen
what is the dermo-epidermal junction
the interface between the epidermis and dermis
what are the functions of the derma-epidermal junction
support, anchorage, adhesion, growth and differentiation of basal cells
semi-permeable membrane acting as a barrier and filter
what are the three layers of the dermo-epidermal junction
lamina lucida
lamina densa
sub lamina dense zone
what types of cells are found in the dermis
mainly fibroblasts
macrophages, mast cells, lymphocytes, langerhans cells
what are the special sensory receptors present in the skin and their function
pacinian corpuscles (pressure) meissners corpuscles (vibration)
how do pacinian corpuscles appear on microscopy
lil onions
what causes hair pigmentation
melanocytes above the dermal papilla
what types of glands are present in the skin
sebaceous
apocrine
eccrine
where are the largest sebaceous glands located?
face and chest
what do sebaceous glands produce
sebum
what are the functions of sebaceous glands
control moisture loss
protection from fungal infection
where are apocrine swear glands found
axillae and perineum
what do apocrine glands produce
oily fluid
what skin structure are apocrine glands associated with
pilosebaceous unit
where are eccrine sweat glands found
the whole skin surface
especially the palms, soles and axillae
what is the nerve supply of the eccrine glands
sympathetic cholinergic nerve supply
which stimuli stimulate the eccrine glands
mental
thermal
gustatory
what are the functions of the eccrine glands
cooling by evaporation
moisten palms/soles to aid grip
what are the main functions of skin
barrier protection metabolism and detoxification thermoregulation immune defence communication sensory functions
how does melanin protect the DNA in the cells’ nucleus
it absorbs UV rays
what are some metabolic processes that occur in the skin
vitamin D metabolism
thyroid hormone metabolism
what is vitamin D3 metabolised from
cholecalciferol (7-dehydrocholesterol)
where is vitamin D3 stored
in the liver
in the presence of 290-320 UV light cholecalciferol is metabolised to
hydroxycholecalciferol (vitamin D3)
vitamin D3 is converted to what in the kidney
1, 25-dihydroxycholecalciferol
thyroxine is converted to which substance in the skin
tri-iodothyronine (T3)
how does the skin thermoregulate
controls sweating, shivering, blood supply
what sensory functions odes the skin have
touch, pressure, vibration
pain and itch
heat and cold
what factors contribute to the skin as an immunological system include
structure (keratin layer, stratification)
cell types (immune system cells and keratinocytes)
cytokines, chemokines, eicosanoids, antimoicrobial peptides
genetics
what is the keratin layer also known as
the stratum corneum
keratinocytes can be activated by ______ and _______ to cause an immune response
UV and sensitisers
what role do keratinocytes play in immunological processes in the epidermis
- sense pathogens via cell surface receptors and help mediate immune response
- produce antimicrobial peptides that can directly kill pathogens
- produce cytokines and chemokines
what is the main resident immune cell in the epidermis
langerhans cells
which type of cell is characterised by the Birbeck granule
langerhans cells
which type of T cell are found in the epidermis
CD8+ (cytotoxic)
which T cells are found in the dermis
CD4+ and CD8+
plasmacytoid DC are found in healthy skin
true/false
false
they are found in diseased skin
what are the main routes of drugs administration involving the skin
topical
transdermal
subcutaneous
what is the biggest barrier to drug penetration in the skin
the stratum corneum (keratin layer)
what are some examples of skin commensal bacteria
staph epidermidis
corynebacterium sp. (diphtheroids)
propionibacterium sp.
staph aureus is coagulase….
postive
what effect does coagulase have
clots plasma
what antibiotic is used to treat staph aureus infection
fluclox fluclox fluclox
some strains of staph aureus produce toxins such as…
enterotoxin (food poisoning)
SSSST staphylococcal scalded skin syndrome toxin
PVL Panton Valentine Leucocidin
what antibiotics can be used to treat MRSA
doxycycline
co-trimoxazole
clindamycin
vancomycin
coagulase negative staphs may cause infection in associated with…
prosthetic material (joints, heart valves, catheters)
beta haemolysis
yellow, complete
alpha haemolysis
green, partial
gamma haemolysis
none
alpha haem. strep includes
strep pneumoniae
strep viridans
non-haem strep are found where
commensal of the bowel
which antibiotic is used to treat group A strep
penicillin
treatment for necrotising fasciitis
urgent surgical debridement
what is tinea pedis
athletes foot
what virus causes chickenpox and shingles
varicella zoster virus
chicken pox is caused by which aspect of VZV
varicella
shingles is caused by which aspect of VZV
zoster
symptoms of chickenpox
generalised rash and fever
distribution of shingles
dermatomal
complications of chickenpox
bacterial infection pneumonitis haemorrhagic rash scarring encephalitis
what causes neonatal chickenpox
VZV infection in mother in late stages of pregnancy
shingels is more common in which patient populations
elderly
immunocompromised
presentation of shingles
tingling/pain
erythema, vesicles and crusts
pain lasting longer than 4 weeks of shingles is called
post herpetic neuralgia
shingles is associated with what type of pain
neuralgic
why is ophthalmic shingles more severe than other forms
it can affect the eye via the nasociliary branch of CNV1
which dermatome does ophthalmic shingles affect
CNV1
how does ramsay-hunt syndrome present
shingles causing vesicles and pain in the auditory canal and throat
complications of Ramsay-hunt syndrome
facial nerve paralysis
irritation of CNVIII (deafness, tinnitus, vertigo)
recurrence of HSV presents as
a blistering rash on the vermillion border
type 1 HSV is the main cause of…
oral lesions
treatment for HSV/VZV
acyclovir
what is acyclovir
anti-viral
analogue of guanosine
how does acyclovir work
it is selectively incorporated into viral DNA inhibiting replication
how does erythema multiforme present
target lesions
which infections may trigger erythema multiforme
HSV
mycoplasma pneumoniae
describe the appearance of molluscum contagiosum
fleshy, firm, umbilicate, pearlescent nodules 1-2 mm in diameter
treatment of molluscum contagious
liquid nitrogen
which virus causes warts
HPV
which types of HPV cause warts
types 1-4
how can warts be treated
salicylic acid
how does herpangina present
blistering rash at the back of the mouth
what causes herpangina
enteroviruses (coxsackie/echovirus)
how is herpangina diagnosed
swab of lesion and stool sample for enterovirus PCR
what causes hand foot and mouth disease
enteroviruses, mainly coxsackie
what is a fatal complication of hand foot and mouth disease
pulmonary oedema
erythema infectiosum is also known as
slapped cheek disease
what casues slapped cheek disease
erythrovirus (parvovirus) B19
presentation of erythema infectiosum
rash on the cheeks, followed by lacy, macular appearance
erythema infectiosum in adults presents with
polyarthritis of small joints
complications of parvovirus B19 infection
spontaneous abortion
aplastic crises
chronic anaemia
diagnosis of erythema infectiosum
parovirus B19 IgM test
what is orf
a sheep virus that affects farmers
how does orf present
firm fleshy nodule on the hands of farmers
what is the presentation of primary infection of syphilis
chancre (painless ulcers at the site of infection)
presentation of the secondary phase of syphilis
red rash over the body, especially the palms and soles
snail track ulcers on mucous membranes
tertiary infection of syphilis
CNS, CV and gummatous manifestations
what bacterium causes syphilis
treponema pallidum
diagnosis of syphilis
blood test or swab of chancre for PCR
treatment of syphilis
penicillin infections
what causes Lyme disease
borrelia burgdorferi
how long does a tick need to be attached to cause Lyme disease
24 hours
early presentation of Lyme disease
erythema migrans
late presentation of Lyme disease
heart block
nerve palsies
arthritis
treatment of Lyme disease
amoxicillin or doxycycline
diagnosis of Lyme disease
presence of erythema migrans
borrelia burdorferi IgG test
Zika presentation
mild fever rash (maculopapular) headaches arthralgia myalgia non-purulent conjunctivas
complications of Zika
microcephaly
Guillain Barre syndrome
what is the ratio of melanocytes of basal cells
1:10
what types of collagen are present in the dermis
types I and III
where is the papillary dermis
just below the epidermis
what is found in the reticular dermis
appendage structures eg sweat glands, pilosebaceous units
what is the epidermal basement membrane made of
laminin and collagen IV
what is hyperkeratosis
increased thickness of keratin layer
what is parakeratosis
persistence of nuclei in the keratin layer
what is acanthosis
increased thickness of epithelium
what is papillomatosis
irregular epithelial thickening
what is spongiosis
oedema between shamus cells that appears to increase prominence of intercellular prickles
what are the 4 main inflammatory skin disease reaction patterns
spongiotic-intraepidermal oedema
psoriasiform
lichenoid-basal layer damage
vesiculobullous-blistering
lichenoid disorders are characterised by damage to what skin structure
basal epidermis
how do lichenoid disorders present
itchy flat topped violaceous papules
how is lichen planus described histologically
irregular sawtooth acanthosis
hypergranulosis and ortohyperkeratosis
band-like upper dermal infiltrate of lymphocytes
basal damage with formation of cymoid bodies
what skin disorder has the following histological appearance;
irregular sawtooth acanthosis
hypergranulosis and ortohyperkeratosis
band-like upper dermal infiltrate of lymphocytes
basal damage with formation of cymoid bodies
lichen planus
examples of immunobullous diseases
pemphigus
bullous pemphigoid
dermatitis herpertiformis
what age group is most commonly affected by pemphigus
middle age
how is pemphigus treated
steroids
what is the most common type of pemphigus
pemphigus vulgaris
what type of antibodies are associated with pemphigus vulgaris
IgG auto-antibodies against desmoglein-3
what is the function of desmoglein-3
desmosomal attachment
what is the pathological process causing pemphigus vulgaris
IgG against desmoglein-3 immune complexes form on cell surfaces complement activation and protease release disruption of desmosomes acanothlysis
where does pemphigus vulgaris commonly present
scalp, face, axillae, groin and trunk
may affect mucosa
how does pemphigus vulgaris present
fluid filled blisters which rupture to form shallow erosions
what is the pathological process causing bullous pemphigoid
circulating antibodies (IgG) react with a major and/or minor antigen of the hemidesmosomes anchoring basal cells to basement membrane this result complement activation and tissue damage
how does bullous pemphigoid present
sub epidermal blisters
immunofluorescence appearance of bullous pemphigoid
linear IgG + complement deposited around BM
what autoimmune condition is dermatitis herpetiformis associated with
coeliac disease
presentation of dermatitis herpetiformis
symmetrical, intensely itchy lesions
elbows, knees and buttocks often affected
what is the hallmark of dermatitis herpetiformis
papillary dermal micro abscesses
pathogenesis of acne
sebum produced by sebaceous gland plugs pilosebaceous unit
keratin and sebum build up to produce comedones (blackheads/whiteheads)
rupture causes acute inflammation and foreign body granulomas
presentation of rosacea
recurrent facial flushing
visible blood vessels
pustules
thickening of skin (rhinophyma)
factors that aggravate rosacea
sunlight
alcohol
spicy foods
stress
chemical mediators of itch
histamine, PGE2, acetylcholine, serotonin, kvllikrein, interleukin 2
what are the 4 causes of itch
pruritoceptive
neuropathic
neurogenic
psychogenic
what causes pruritoceptive itch
something (usually associated with inflammation or dryness) in the skin causes itch
what causes neuropathic itch
damage of any sort to central or peripheral nerves
define neurogenic itch
no evident damage in CNS but itch is caused by something acting on CNS receptors (eg opiates)
what causes psychogenic itch
psychological causes with no CNS damage (eg itch with delusions of infestation)
what is dermographism
stroking the skin causes excessive mast cell degranulation and release of histamine and other within-skin mediators resulting in a raised white mark, with surrounding erythema
examples of pruritoceptive itch
lichen planus, eczema, insect bites, psoriasis,
what types of systemic diseases are associated with itch
haematological paraneoplastic liver and bile duct psychogenic kidney disease thyroid disease
what is the commonest form of psoriasis
chronic plaque psoriasis (psoriasis vulgaris)
what is Koebner phenomenon
psoriasis developing in an area of trauma
what is Auspitz sign and what is it is sign of
removal of scale surface reveals tiny bleeding point (dilated capillaries in elongated dermal papillae)
psoriasis
what are the 4 types of psoriasis
chronic plaque (psoriasis vulgaris)
guttate
palmoplantar pustular
erythrodermic/widespread pustular
nail signs of psoriasis
onycholysis (separation of nail from nail bed)
nail pitting
dystrophy
subungual hyperkeratosis
why do people with severe psoriasis have a life expectancy reduced by about 4 years
increased CV risk
topical therapies for psoriasis
vitamin D analogues (calcipotriol, calcitriol) coal tar dithranol steroid ointments emollients
specialist treatments for psoriasis
phototherapy (narrow band UVB and PUVA) systemic treatments (immunosuppression eg methotrexate, immune modulation eg biologic agents
initial management of acne
oral antibiotic (doxycycline) topical retinoid
second line acne management
oral isoretinoin (systemic retinoid)
side effects of isoretinoin
causes initial flare of acne for 2-3 weeks
congenital defects
what is acne vulgaris
chronic inflammatory disease of the pilosebasceous unit
what sites are most affected by acne vulgaris
face, upper back, anterior chest
morphological description of acne vulgaris may include
comedones (open = blackhead, closed = whitehead)
pustules and papules
cysts
erythema
how does rosacea differ from acne
no comedones as there is no involvement of the pilosebaceous unit
what is rhinophyma
enlarged/unshapely nose
associated with rosacea
topical therapy for rosacea
metronidazole
ivermectin (reduce demodex mite)
oral therapy for rosacea
tetracycline long term
isoretinoin low dose if severe
sites commonly affected by lichen planus
volar triste/forearms, shins and ankles
what is Wickham’s striae and what is it a sign of
fine lace-like pattern on the surface of papules and buccal mucosa
lichen planus
how long does lichen planus normally last
12-18 months
treatment of lichen planus
topical steroids (oral steroid is extensive)
how to differentiate between pemphigus vulgaris and bullous pemphigoid
bullous pemphigoiD - the split is Deeper, through the DEJ
pemphiguS - split is more Superficial, intra-epidermal
what is Nikolsky’s sign and what is it associated with
the top layers of the skin slip away from the lower layers with slightly rubbed
pemphigus
is bullous pemphigoid associated with blisters
yah, blisters burst to leave erosions
Nikolsky’s sign is positive in bullous pemphigoid
true/false
false - the split in BP is not intra-epithelial
bullous diseases may initially present with urticated itchy plaques
true/false
true
is mucosal involvement common in bullous pemphigoid, pemphigus vulgaris or both
pemphigus
tense bullae are associated with…
flaccid bullae are associated with…
tense = bullous pemphigoid flaccid = pemphigus
which bullous disorder has the worse prognosis
pemphigus
signs of acute phase eczema
papulovesicular rash
erythema
oedema (spongiosis)
ooze or scaling and crusting
signs of chronic phase eczema
thickening (lichenification)
elevated plaques
increased scaling
how is contact allergic dermatitis investigated
patch testing
what is the typical distribution of atopic eczema
flexural distribution
what causes eczema herpeticum
HSV
morphology of eczema herpeticum
monomorphic punched-out lesions
diagnostic criteria fro atopic eczema
itching + 3 or more of; visible flexural rash** history of flexural rash** history of atopy dry skin onset before 2 yo **cheeks and extensor surfaces in infants
which gene is most significant in the development of atopic eczema
filaggrin
stasis eczema is secondary to
hydrostatic pressure
oedema
red cell extravasation
what is ash-leaf macule a sign of
tuberous sclerosis
what tumours are associated with tuberous sclerosis
periungual fibromas (around nails)
facial angiofibromas
hamartomas (angiomyolipomas - heart, lung, kidneys)
bone cysts
why is tuberous sclerosis associated with seizures
cortical tubers and/or calcification of falx cerebri
presentation of epidermolysis bullosa
blistering at birth
type of epidermolysis bullosa
simplex
junctional
dystrophic
result of haploinsufficiency
only one copy of working - reduced protein production
result of dominant negative mutation
expression of abnormal protein interferes with normal protein
result of gain of function mutation
mutant protein gains new function, affecting cell processes
result of autosomal recessive mutations
2 faulty copies of gene produce no protein
cafe au lait macules
neurofibromatosis type 1
presentation of NF1
cafe au lait neurofibromas plexiform neuroma axillary or inguinal freckling optic glioma lisch nodules bony lesions
ichthyosis vulgaris is caused by a mutation in which gene
filaggrin
ABCDE melanoma
asymmetry borders colour diameter evolution
what is the ugly duckling sign
a mole that looks different from all the others on a patients skin is more likely to be melanoma
describe appearance of BCC
pearly/translucent slow growing lump or non-healing ulcer visible blood vessels central ulceration scaly plaque
what is a morphoeic BCC
infiltrative
SCC presentation
hyperkeratotic (crusted lump or ulcer
fast growing
painful, bleeding
precursor lesions for SCC
actinic keratoses
Bowen’s disease (carcinoma-in-situ)
where does SCC tend to present
sun-damaged skin
what are actinic keratoses
precancerous skin lesions
risk factors for skin cancer
sun exposure genetic predisposition immunosuppression (HPV infection) environmental carcinogen
what is Gorlin’s syndrome
nevoid basal cell carcinoma syndrome
presents with early onset/multiple BCCs, palmar pits, jaw cysts and ectopic calcification falx
what are melanocyte precursor cells called
melanoblasts
when do melanblasts become melanocytes
when they settle in the skin
what sort of melanin causes red hair
phaeomelanin
which gene determines skin pigment and hair colour
melanocortin 1 receptor gene
what is the function of the MC1R gene
turns phaeomelanin into eumelanin
what is the science name for freckles
ephilides
what are actinic/solar lentigenes
liver/age spots
what causes actinic lentigenes
increased melanin and basal melanocytes
epidermis elongated rete ridges
what are the two types of dysplastic naevi
sporadic
familial
presentation of sporadic dysplastic naevi
one to several atypical naevi
presentation of familial dysplastic naevi
strong FH of melanoma
lots of atypical naevi
how does familial dysplastic naevi affect risk of MM
lifetime risk of melanoma up to 100%
what are halo naevi
naevi with a peripheral halo of depigmentation
what are blue naevi made up of
pigment rich dendritic spindle cells
where are blue naevi found
dermis
what colour are spitz naevi
pink
due to prominent vasculature
what are the four main types of malignant melanoma
superficial spreading
acral/mucosal lentiginous
lentigo maligna
nodular
melanomas in which growth phase can metastasise
vertical growth phase
how does the growth of nodular melanoma differ from the other types
there is no evidence of radial growth phase
how is melanoma prognosis measured
Breslow depth
melanoma poor prognostic factors
ulceration high mitotic rate lymphovascular invasion satellites sentinel lymph node involvement
treatment of melanoma
primary excision to give clear margins
treatment if melanoma with positive sentinel nodes
primary excision + regional lymphadenectomy
treatment of melanoma with mets
chemo, immunotherapy, genetic therapies
what is seborrhoeic keratosis
benign proliferation of epidermal keratinocytes
were are seborrhoeic keratoses most common
on the face and trunk
what is Leser-Trelat sign
eruptive appearance of many seborrhoeic keratoses that may indicate internal malignancy
presentation of Bowen’s disease
scaly patch/plaque
irregular border
no dermal invasion
atypical presentations of SCC
chronic leg ulcers (stasis ulcers)
sites of burns
chronic lupus vulgaris
specific sites of poor prognosis for SCC
scalp, ear, nose
definition of chronic leg ulcer
a open lesion between the knee and ankle joint that remains unheralded for at least 4 weeks
swab a leg ulcer?
only if there are signs of infection - increasing pain/exudate/smell/enlarging
treatment of venous ulcer
4 layer compression bandaging
leg elevation
indications for surgery: rash
assist in diagnosis
indications for surgery: tumours
assist in diagnosis
remove malignancy
remove unwanted skin growth (cosmesis)
types of skin disease caused by adverse reaction to amoxicillin
morbilliform (measles like) eruption urticaria angiodema fixed drug eruption generalised pustulosis
what is imiquimod cream used to treat?
actinic keratoses
superficial BCC
treatment of precancerous skin lesions
cryotherapy solaraze 5 FU PDT imiquimod resurfacing
what are the 5 layers of the scalp
skin connective tissue aponeurosis loose connective tissue periosteum
