dermatology - high yield Flashcards
what is the water proof barrier of skin
keratin layer
what does the keratin layer contain
corneocytes
what does the granular layer consist of
large keratinocyte granules
what do the large keratinocyte granules conatain
fillagrin and involucrin
what does the prickle cell layer contain
desmosomes that anchor cells together
what is the epidermal layer closest to the dermis
basal
how thick is the basal layer
one cell thick
what is the metabolically active layer of the epidermis
the basal layer
what are the 4 epidermal cells
keratinocytes, langerhans cells, merkel cells and melanocytes
what makes up 95% of the cells in the epidermis
keratinocytes
where do keratinocytes originate
in the basal layer
where do keratinocytes end up
in the stratum coneum
what do keratinocytes do
produce cytokines and are involved in immune response
where are melanocytes found
in the basal layer
what do melanocytes do
produce melanin that forms a protective overcap over the nucleus of cells
what is eumelanin
brown/black
what is phaemelanin
red/yellow
where are langerhans cells found
in the prickle cell layer and dermis
where are langerhans cells formed
in bone marrow
what are langerhans cells
dendrictic cells involved in the immune system
how to langerhans cells work
attach to antigen and present it in the lymph nodes
where are merkel cells found
in the basal layer
what are merkel cells
mechanoceptors sensitive to light touch
anagen
growth phase
how long does anagen last
3-7 years
catagen
involuting stage
how long does catagen last
28 days
what is telogen
resting phase
when does telogen occur
everyday
3 layers of the dermis
lamina lucida, lamina densa, sub lamina densa zone
what does the dermis contain
fibroblasts, macrophages, langerhans cells, mast cells
what senses vibration
meissners corpuscles
what senses pressure
pacinian corpuscles
what senses painful stimuli
free nerve endings
where are aebaceous glands found
everywhere - especially face, chest and upper back
what gland is affected in acne
sebaceous gland
what are apocrine glands part of
pilo sebaceous unit
what do sabaceous glands release
oil
what do apocrine glands produce
oily fluid, odorous
why is the oily fluid smelly in apocrine glands
due to decompisition by bacteria
where are apocrine glands found
armpits, groin, eyelids, ears
what is the function of eccrine glands
cool down the body
where are eccrine glands found
everywhere especially hands, feet armpits and forehead
what is the role of keratinocytes
to release chemokine and cytokine and sense pathogens via surface receptors and produce anti microbial peptides that kill pathogens
what are the main antigen presenting cell in skin
langerhan cells
what do langerhan cells contain
birbeck granule
what to langerhans cells do
present pathogens to T cells
what T cells are found in the epidermis
CD4 and CD8
what T cells are found in the dermis
CD4 T cells
what T cells are involved in inflammation
CD4 and T helper cells
what T cell is psoriasis associated with but dermatitis isnt
TH1
what t cell is atopic dermatitis associated with but psoriasis isnt
TH2
what t cell is associated with both psoriasis and atopic dermatitis
TH17
examples of conditions with inappropriate inflammatory responses
psoriasis, urticaria, skin tumours, atopic dermatitis, bullous pemphigoid and SLE
what are prophyrias
manifestations in the skin due to accumulations of porphyrins
what does reduced activity of the enzymes that produce heam lead to
increase porphyrins
what is prophyria cutanea tarda due to
reduced activity of uroprophrinogen decarboxylase
symptoms of prophyria cutanea tarda
blisters, milia, hyperpigmentation, hypertrichosis, solar urticaria
how to diagnose prophyria cutanea tarda
plasma screen and urine test (woods lap)
what is erythropoietic protophyria caused by
reduced activity of ferrochelectase
signs of erythropoueric protophyria
burning senstation, no physical signs, pain in sunlight, swelling and itching
investigations of prophyrias
plasma screen, RBC porphyrins, transaminases
what causes acute intermittent porphyria
reduced activity of PBG deaminase
what is the lamina propia
a layer of loose connective tissue found in mucous membranes like the respiratory tract
what builds up in acute intermiitent porphyrias
porphobillogen
what builds up in erythropoietic protoporphyria
protoporphyrin
what type of hypersensitivity is bullous pemphigoid
type 2
what causes bullous pemphigoid
auto antibody deposition on the basement membrane
what are the auto antibodies in bullous pemphigoid developed against
hemi desmosomes
clinical features of bullous pemphigoid
deep tense blisters which are itchy and located around the flexures
is the nikolsky sign in bullous pemphigoid positive
no
who does bullous pemphigoid tend to affect
the elderly population
how to diagnose bullous pemphigoid
skin biopsy and immunofluorescence
what does immunoflourenscece in bullous pemphigoid show
deposition of IgG and C3 at the dermo epidermal junction
what is the management of bullous pemphigoud
potent topical corticosteroids or oral corticosteroids, immunosuppressants and antibiotics
what is pemphigus vulgaris
an autoimmune condition where there is deposition of IgG autoantibodies in the epidermis
clinical features of pemphigous vulgaris
flaccid, superficial blisters that are painful but nt itchy
is the nikolksy sign positive in pemphigus vulgaris
yes
what is the most common presenting symptom of pemphigous vulgaris
oral mucosa being affected
what has a higher mortality pemphigus vulgaris or bullous pemphigoid
pemphigoid vulgaris
how to diagnose pemphigoid vulgaris
skin biopsy and immunofluorescence
what does immunofluorescnce of pemphigus vulgaris show
deposition of IgG auto antibodies in the epidermis causing a chicken wire appearance
what is the management of pemphigus vulgaris
oral corticosteroids
what is dermatitis herpetiformis
an autoimmune condition caused by deposition of IgA autoantibdies in the dermis
what is dermatitis herpetiformis strongly correlated with
coeliac disease
clinical features of dermatitis herpetiformis
itchy, vesicular lesion on the extensor surfaces
diagnosis of dermatitis herpetiformis
skin biopsy and immunofluorescence
what does immuno fluresnce in dermatitis herpetiformis look like
deposition of IgA in granular pattern in the upper dermis
what is the management dermatitis herpetiformis
gluten free diet - dapsone can help
what are the antibodies against in pemphigous vulagris
desmoglein
what is epidermolysis known as
butterfly skin
inheritance of epidermolysis
autosomal dominant usually
history of epidermolysis
young child with fragile skin blisters all over body rubbing skin causes painful tear
presentation of actinic keratosis
scaly rash over temples and nose which has lesions red and pink in colour
risk factors for actinic kertosis
outdoor occupation, pale skin, not applying suncream
presentation of psoriasis
symmetrical sharply demarcated scaley erythematous plaques involving extensor surfaces, scalp, sacrum, hands, feet trunk and nails
peak onset of psoriasis
15-25 or 50-60
cause of psoriasis
multifactorial
histology of psoriasis
epidermal acanthosis, parakeratosis, elongated rete ridges on histology
presentation of guttate psoriasis
acute and spotty
presentation of palmoplantar pustular
painful to walk on
what does psoriasis demonstrate
koebner phenomenon and auspitz sign
systemic disease associated wuth psoriasis
psoriasitic arthritis, metabolic syndrome, crohns, cancer, uveitis, depression, alcohol, smoking
managemnet of psoriasis
vit d analogue, coal tar, dithranol, steroids, keratinolytics, photo therapy, immunosuppression and immune modulation
examples of vit D analogues
calcitriol calcipotriol
pathophysiology of eczema/dermatitis
spongiosis and inflammatory cell infiltertrate
presentation of eczema/dermatitis
ill defined erythematois itchy rash
pathogenesis of contact allergic dermatitis
type 4
histology of contact allergic dermatitis
spongiotic dermatitis
pathogenesis of contact irritant dermatitis
trauma (soap, water)
histology of contact irritant dermatitis
spongiotic dermatitis
pathogenesis of atopic dermatitis
genetic and environmental factors resulting in inflammation
histology of atopic dermatitis
spongiotic
pathogenesis of drug related dermatitis
type 1 or 4
histology of drug related dermatitis
spongiotic and eosinophils
pathogenesis of photo inficed dermatitis
reaction to UV light
histology of photo induced dermatitis
spongiotic
pathogenesis of lichen simplex
physical trauma to skin - scratching
histology of lichen simplex
songiotic dermatitis and external trauma
pathogenesis of stasis dermatitis
physical trauma to skin - hydrostatic pressur e
histology of stasis dermatitis
spongiotic dermatitis and extravasation of RBCs
what is Th2, IL4, 5 and 6 and filaggrin gene mutation assocated with
atopic dermatitis
diagnosis of atopic dermatitis requires
itch plus 3 or more of the followng - visible flexural rash, history of delxural rash, history of atopy, generally dry skin, onset before the age of 2
management of atopic dermatitis
irritant avoidance, soap substitution, emollient, topical steroids, photo therapy, systemic immunosuppressants, biologics
what is acne vulgaris
inflammatory disease of pilosebaceous unit
process of acne development
increased production of sebum, poral occlusion, cutibacterium acne colonisation, dermal inflammation
features of acne
comedones, pustules, papules, cysts, nodules, erythema, sebborhoea
secondary features of acne
scarring - atrophic, icepick, hypertrophic/keloid, hyperpigmentation
what does acne mostly affect
face, upper back, anterior chest
management of acne
avoid oily substances, benzoyl peroxed, vit A derivative, antibiotics
systemic management of acne
antibiotic - tetracycline, isotretinoin
who does rosacea typically affect
women aged 30-60
features of rosacea
papules, pustuesm erythemia of nose chin, cheeks, forehead, facial flushing
what can rosacea cause
rhinophyma, telangiectasia, conjuctivitis
management of rosacea
avoidance of aggravating factors, topical antimicrobials, oral tetratcycline
example of topical antimicrobial
metronidazole, ivermectin
how can rhinophyma be treated
with isotrenoin, vascular laser and surgery
who does lichen planus affect
middle aged
pathophysiology of lichen planus
T cell mediated inflammation targeting unknown protein in skin and mucosal keratinocytes
lichen planus features
violaceous flat topped shiny papules affecting volar wrists, forearms, shins, ankles, wickhams striae
what is wickhams striase
longitudinal nail ridges, hyperpigmentation, hypertrophy
management of of lichen planus
emollients symptomatic topical oral steroids, photo therapy
how long does lichen planus last
12-18 months
first line management of psoriasis
emollient, potent corticosteorid, vit D analogue
histology of psoriasis vulgaris
acanthosis