Skin Flashcards
Identify the occluded structures
what structure pointed to
Meissner’s Corpuscle
what structure in the skin is this
Pacinian corpuscle
Dermatophytes are a fungi that need what structural epidermal protein for growth
karatin
In which layer does 7-dehydrocholesterol conversion to Vit D3 occur?
stratum spinale
mn: S for Spinale and Synthesis
In which layer are melanocytes found
stratum basale
what are the numbered regions of the epidermis
1: stratum basale
2. stratum spinale
3. stratum granulosum
4. stratum lucidum
5. stratum corneum
identify sebacious gland versus sweat gland
3 = sweat gland (exits to the external environment)
4 = sebaceous gland (responsible for greasy hair and shiny baldness)
Characterize Pemphigus Vulgaris
Etiology: rare autoimmune disorder
Macroscopic: blisters that easily pop
Microscopic: see photo: separation between stratum corneum and stratum basale (ie suprabasal). Tombstone row
Pathology: IgG attacks desmoglein 1 and 3
what are acantholytic cells?
rounded-up separated keratinocytes within the blisters in the upper layers of the epidermis.
Characterize Pemphigus foliaceus
Etiology: rare autoimmune disorder (more common than pemphigus vulgaris)
Macroscopic: blisters that easily pop
Microscopic: see photo: separation between stratum corneum and the lower layers of the skin (ie subcorneal)
Pathology: IgG attacks desmoglein 1
what are the 4 cell types in the epidermis
Keratinocytes
Melanocytes
Langerhans (dendritic) cells
Merkel cells (receptors)
what are the infections that can typically lead to classic “bulls eye” appearance
B. burgdorferi, Rickettsia rickettsii, and Ehrlichia chaffeensis
what are the different types of immune cells in the epidermis versus the dermis?
Epidermis: keratinocytes, Langerhans cells, intraepithelial lymphocytes (IELs) provide first line of defense in the outer epidermal layer
Dermis: T cells, dendritic cells, macrophages, and mast cells
True or false?
T cells can make it into the epidermis to assist with immunity
True
What are the treatments of choice for minor versus more serious dermatophyte infections?
minor - depends on subtype so that it can be more targeted
major: Griseofulvin (has GI side effects)
Malessezia furfur causes what skin condition
other facts:
- it does well in hot humid environments.
- it produces melanocyte damaging acids via lipid degradation (because they are lipophilic), however it is classified as superficial
- sits on surface of skin and stays relegated to the stratum corneum
- treatment: “Selsun blue (selenium sulfide)
what fungal infection can cause this presentation of the skin
malessezia furfur (ie tinea versicolor)
True or false: tinea unguium is the same thing as onychomycosis
TRUE -they both refer to tinea /dermatophyte infection in the nails.
What causes vitiligo
autoimmune destruction of melanocytes (so there’s a decrease)
mn: the V in Vitiligo is pointing down to show the decrease in melanin)
loss of which epithelial junction type is associated with tumor metastasis?
the tight junctions –> E-Cadherin
Most cancers originate from epithelial tissue and E-cadherin is critically important in organizing the epithelium. The function of E-cadherin is altered in most epithelial tumors
What characterizes the pemphigus family of disorders
failed cell-to-cell adhesion.
Pemphigus is an autoimmune condition characterized by the disruption of cadherin-mediated cell adhesions. All forms are caused by autoantibodies that bind to the proteins in a subfamily of the cadherins, known as the desmogleins. Antibody binding to desmogleins prevents their function in cell adhesion. Therefore, adjacent epidermal cells are unable to adhere to each other and blisters develop.
What is the most abundant intercellular junction type in epithelial cells
desmosomes
The Malpighian layer consists of the stratum _______ and stratum ________.
The Malpighian layer consists of the two deeper layers, the stratum basale and stratum spinosum.
Where are the apocrine glands found (4)
Apocrine sweat glands are found in or around the:
Axillae
Areola
Perianal region
External genitalia
Mn: Apes are stinky and so are the places where apocrine glands are found
what are gap junction scomposed of
1 gap junction is composed of 2 connexons (or hemichannels) which connect across the intercellular space. Each connexon is composed of 6 connexins.
what features contribute to the normal flora of the skin
- nature of secretions,
- normal clothing worn, and
- immediacy to mucus membranes.
pathology of albinism
Patients have normal melanocyte numbers with decreased melanin production due to decreased tyrosinase activity or defective tyrosinase transport.
On the ____________side of the plasma membrane, there are two dense structures called the outer dense plaque (ODP) and the inner dense plaque (IDP), spanned by the desmoplakin protein.
cytoplasmic side
what is the distinction between an apocrine gland and a sebacious gland
Tight junctions are made up of integral membrane proteins (3):
Occludins
Claudins
JAMs (junctional adhesion molecules)
What type of cell junction type do integrins participate in
Integrins maintain integrity of the basolateral domain by binding to laminin and collagen within the basement membrane. Integrins define cellular shape, mobility, and regulate the cell cycle.
what type of cell junction anchors the actin cytoskeleton through E-cadherins.
Zonula adherens
melanin production is triggered by what 4 factors
Sun exposure
MSH (Melanocyte Stimulating Hormone)
Estrogen
Progesterone
timeline of skin cell migration
about two weeks for a cell to migrate from the stratum basale to the stratum granulosum and another two weeksto cross the stratum corneum.
autoimmune disorders associated with Vitiligo (4)
- Type 1 diabetes
- Pernicious anemia
- Primary adrenal insufficiency (Addison disease)
- Alopecia areata
in addition to just waiting, you can treat malasma with what drug
hydroquinone
inhibits tyrosinase leading to decreased conversion of dopa to melanin.
hemidesmisome structure and proteins
Most common organisms found colonizing the skin are:
Staphylococcus epidermidis (up to 90% of skin flora)
Staphylococcus aureus (10-40%)
Micrococci luteus (20-80%)
Diphtheroids (bacteria belonging to the genus Corynebacterium)
what skin distributions are sebacceous glands found on
All skin areas except palms of hands and soles of feet
T/F:
The number of melanocytes is essentially the same between the sexes and different races.
True
what is actinic keratosis
a red scaly skin growth usually caused by sun exposure, which could become squamous cell carcinoma
The risk of actinic keratosis progression to squamous cell carcinoma is proportional to the degree of epithelial dysplasia
most common among older populations
a wheal is caused by epidermal or dermal swelling
dermal
top 3 causes of stevens-johnson syndrome
in order of commonness: medications, followed by infections and (rarely) cancers.
What is Nikolsky’s sign?
Slight mechanical pressure (by rubbing) is exerted on the skin → upper epidermal layer slips away from lower layer →separation of epidermis → blistering
Nikolsky’s sign is present in
- pemphigus vulgaris ,
- toxic epidermal necrolysis,
- staphylococcal scalded skin syndrome,
- scalding,
- bullous impetigo, and
- Stevens-Johnson syndrome
Not present in bullous pemphigoid
Acanthosis vs acantholysis
acanothosis = diffuse epidermal thickening (presents with hyperkeratosis)
acantholysis = loss of connections between keratinocytes
what is plaque psoriasis
a chronic inflammatory skin disorder characterized by well-demarcated pink plaques with a silver white scale (see picture). These plaques commonly affect the extensor surfaces of the knees and elbows
the TB test is an example of which type of hypersensitivity reaction?
IV
contact dermatitis is an example of which type of HSR?
Type IV
Type 1 HSR are characterized by ___ and ___
IgE
Mast cell degranulation
More than 95% of Staphylococcus aureus isolates are resistant to penicillin. Therefore, they must be treated with other beta-lactam antibiotics such as ______________ or ___________
cephalosporins or vancomycin.
collagen is produced by what cell type
fibroblasts
what collagen type is involved in formation of granulation tissue?
type III (poor tensile strength)
(which later gets replaced by type 1)
How might Ehlers Danlos syndrome affect wound healing?
impaired collagen production therefore impaired wound healing
What are the factors that would cause abnormal tissue repair
- Keloids (excessive collagen production) –> more common in african americans
- Diabetes Mellitus
- Persistent infection (usually due to MRSA in a hospital setting)
- Nutritional deficiencies:
- Protein deficiency
- Vitamin C deficiency
- Ehlers-Danlos Syndrome (defects in types I and III collagen synthesis)
cellulitis versus erisypelas
what is SSSS
Staphylococcal scalded skin syndrome
In infants under six years of age or adults with renal insufficiency, localised bullous impetigo due to specific staphylococcal serotypes can lead to a sick child with generalised staphylococcal scalded skin syndrome (SSSS). Superficial crusting then tender cutaneous denudation on the face, in flexures, and elsewhere is due to circulating exfoliatin/epidermolysin, rather than a direct skin infection. It does not scar.
what skin condition is pictured?
measles (viral infection by paramyxovirus)
key bacteria that can cause skin infections
Staphylococcus aureus (the other species are part of normal flora) and Streptococci spp.
Strep classifications* to know:
- Streptococcus pyogenes Lancefield group A,
- Streptococcus agalactiae Lancefield group B,
- Streptococcus pneumoniae
- Viridans group of streptococci.
*Lancefield classifications are based on cell wall carbohydrate composition
This condition ocurred a few weeks after strep. pygogenes infection. What is a reasonable dx?
Rheumatic fever (progression from scarlet fever)
the bacteria involved is strep pyogenes.. what’s a reasonable dx?
scarlet fever
Rosacea and SLE have a similar clinical presentations visually, how do you differentiate between them
Rosacea and SLE have a similar clinical presentation in that they both have:
- erythemous patches around nasolabial region
- no comodones
- triggered by sun, alchol, and spicy food
What differentiates them:
- Rasacia is characterized by talengiectasia (tiny blood vessels) and is more butterfly in shape
- notice these differences in the photo attached
*also, atopic dermatitis is differentiated by being not in the nasolabial distributions, being scattered, and in addition, they more commonly present as vessicles
tx for rosacea?
- topical metronidazole
- oral tetracycline
- avoid sun, wear sunscreen
what is glabrous skin
skin that has no hair, found on palm of hand and sole of feet –> thick skin
what is desquamation
the shedding of skin cells (normal)
what is the first waterproof layer of the epidermis and why
stratum granulosum
These cells contain keratohyalin granules, which are filled with histidine- and cysteine-rich proteins that appear to bind the keratin filaments together. …
At the transition between this layer and the stratum corneum, cells secrete lamellar bodies (containing lipids and proteins) into the extracellular space –> lipid =waterproof
what enzyme is responsible for melanin production
tyrosinase in melanosomes
when the granules in malanosomes run out of tyrosinase activity, they are secreted by melanosomes into the skin and are now called “melanin” granules
vitiligo vs albinism?
vitiligo= loss of melanocytes (no melanocytes) in that particular area
albinism =problem with tyrosinase activity (usually a deficiency of the enzyme)
what is a pilosebaceous unit?
sabaceous gland + arrector pili smooth muscle
*arrector pili is sympathetic innervation –> contraction causes goose bumps
T/F: merkel cells have desmosomes
true.. they need to be anchored down
sabaceous gland versus apocrine gland
sabaceous gland exits via duct to a hair follicle –> secretes sebum. It is a simple branched acinar gland. NOT a sweat gland
epocrine = a sweat gland present in axilla and anorectal (thin hairy skin). it also exits via duct to hair follicle - secretes sweat. it is a simple coiled tubular gland
how does hair form
a hair follicle is an invagination of the epidermis into the dermis and hypodermis (see photo). the follicle produces fused keratinocytes
unlike pacinian corpuscles, meissner corpuscles are found in the _______layer of the dermis
papillary
pacinian are found in the reticular layer
pemphigus foliaceus –> which desmoglein is affected?
In pemphigus foliaceus, autoantibodies bind to a protein called desmoglein-1, which is found in desmosomes in the keratinocytes near the top of the epidermis. The result is the surface keratinocytes separate from each other, and are replaced by fluid: the blister. Because the blister is very close to the surface of the skin, the blisters rupture easily. In most cases, the autoantibodies are immunoglobulin type G (IgG) but in IgA pemphigus, the autoantibodies are type A (IgA).
skin begins to form after what major event(s) in embyronic development
after closure of the cranial and caudal neuropores, which occurs by day 25
the development continues from 2-5 months
what does the skin derive from
epidermis derives EXCLUSIVELY from ectoderm (including melanocytes, sensory receptor cells, and nerves which derive from neuroectoderm)
dermis derivation is site dependent:
- face and anterior forehead dermis comes from ectoderm
- dorsal body wall mesenchyme derives from somites
- limb and ventral body wall mesenchyme derives from lateral plate mesoderm
embryonic period is weeks
3-8
fetal period is weeks
9 weeks -birth
ectodermal subderivations
what is dermal mesenchyme
mesenchyme is undifferentiated stem tissue. dermal mesenchyme has a dermal progenitor
T/F: epidermis derives exclusively from ectoderm
TRUE
melanocytes derive from ________ and appear by day __
melanocytes derive from neuroectoderm and appear by day 50
epidermal appendage formation occurs at what stage of embryonic development
STAGE 2: Early Fetal Period, months 2-5
at what stage of embryonic development do granular and stratum corneal layers form?
STAGE 3: late fetal period (months 5-9)
scar tissue after 3 months is primarily composed of acellular connective tissue (Type I collagen)
accumulation of blood vessels and fibroblasts would indicate what stage of tissue repair by fibrosis
step 2: granulation tissue formation
what type of collagen is scar tissue
type I
how does vitamin C deficiency affect wound healing
vitamin C hydroxylates lysine and proline so that the collagen (all tyeps) can form. deficiency = less collagen
the first inflammatory cell to come in is the neutrophil
skin injury has to heal by scar formation when _______
it injures all the way to the non-labile cells (ie to the dermis)
otherwise it will heal by regeneration because epidermal cells are labile
what type of tissue (labile, stable, permanent) is liver
stable
Answer: type 1 collagen (described as “wall to wall blue” on histology)
by contrast, type 1 collagen is whispy blue
keloid scar tissue is made of _________ collagen
Type I –> in excess
T/F
tissues can attempt to form a scar around tumor invasion –> presents as fibrosis
TRUE
e.g. desmoplasia in pancreatic cancer
answer: secondary intention
*by contrast tertiary tissue is “a giant mess and usually infected”
FALSE –> it is a granuloma. notice the giant cells
Picture attached compares granuloma with granulation tissue
skin presentation with a sheel and flare is characteristic of what type of HSR
Type 1 –> what you see in a skin prick test at an allergist’s office
**TB test can look similar (swelling/flare), though smaller, but it is type IV
Early phase vs late phase components that facilitate Type I HSR
atopic dermatitis is most common in what age group
kids younger than 5
parakeratosis
junctional vs compound vs intradermal nevi
location of merkel cells
example of ezcema
Epidermal accumulation of edematous fluid in the intercellular spaces, referred to as spongiosis, is the characteristic histologic finding in what skin condition?
this histological characteristic is called spongiosis and is commonly seen in atopic dermatitis
characteristic pathology of pemphigous vulgaris
pemphigus foliacious versus pemphigus vulgaris
foliacious bilstering is more superficial –> subcorneal (Desmoglein 3)
vulgaris is more deep –> intraepithelial (aka suprabasal) (Desmoglein 1)
characteristic findings in bullous pemphigoid
which layer of skin is affected in dermatitis herpateformis
Dermal papillary collections of neutrophils (microabscesses)
Direct IF : granular IgA deposits in dermal papillae
which genetic mutation is implicated in patient with fam or personal hx of asthma and atopic dermatitis?
- Loss of function mutations in filaggrin = a strong risk factor for atopic dermatitis, asthma and food allergies (atopic triad)
- Filaggrin – a protein expressed by keratinocytes in the skin with multiple functions
- Helps maintain tight junctions in the epithelial barrier
- peptide breakdown products help moisturize skin
- keeps pH of skin low
- Filaggrin – a protein expressed by keratinocytes in the skin with multiple functions
what is the characteristic histopathological finding in contact dermatitis?
more so that infiltrate of inflammatory cells
***However, eczema also has vessicle formation in the epidermis
what is the hallmark histopathological sign in atopic dermatitis
(aka eczema)
epidermal spongiosis
hallmark histopathological sign in urticaria
dermal edema
what is the classic histopathological finding in psoriasis
epidermal neutrophils
Wikham Striae is characterstic of what skin disease
lichen planus
white, lacy, reticulated patches in oral mucosa = diagnostic of lichen planus
what are the characteristic histopathological findings in lichen planus
- citoid bodies,
- dermal epidermal lymphocytes (sawtooth infiltrate of lymphocytes at dermal-epidermal junction)
- hyperkeratosis
what is the auspitz sign and what disease is it characteristic of
Auspitz’s sign is the appearance of punctate bleeding spots when psoriasis scales are scraped off
what are the main cytokines involved in chronic inflammatory dermatoses
TNF
IL-2
IF-gamma
IL-17
answer: seborrheic dermatitis
seborrheic dermatitis often presents with ____ in addirtion to rash
dandruff
T/F: Erysipelas involves both dermis and superficial cutaneous lymphatics?
TRUE
Erysipelas p/w sharp demarcation –> probably because the infection spreads along cutaneous lymphatics
(to differentiate this with cellulitis –> note the clearly demarcated edges)
most common cause of impetigo is _____________
staph aureus (but second to that most likel is pyogenes)
cathelicidin-vasodilation occurs in what skin condition
rosacea
what is the most common skin infection
acne
Koilocytosis assoc with what type of warts
verruca vulgaris
answer:
molluscum contagiosum (Pox virus)
hypertrophic osteoarthropathy
Hypertrophic osteoarthropathy is a medical condition combining clubbing and periostitis of the small hand joints
pathogenesis of clubbed nails (hypertrophic osteoarthropathy)
autoimmune
what is this
Onychomycosis, also known as tinea unguium
basically a fungal infection of the nail
what is onychocryptosis?
ingrown nail
what is the etiology of this
psoriasis
alopeacea areata
what is paronychia
what is this and what is its etiology
Beau’s lines caused by
many different causes
nail anatomy. what’s the occluded area
lunula
clues: papules in a line and yeast in the histo = sporothrix shigellia infection causing sporotrichosis which is growing in a yeast form in tissue and in culture at 37° C (98.6° F) but as a filamentous fungus at 30° C (86° F). The mycelial form has fine, septate, branching hyphae that carry perpendicular ovoid roseate conidia.
