1 - Epidermis and Derm Terms Flashcards
Describe the Epidermis? What is its function?
Derived from ectoderm, outermost layer of the skin, barrier function.
What are the layers of the epidermis from superficial to deep?
- Stratum corneum
- Stratum granulosum (granular layer)
- Stratum spinosum
- Stratum Basale
Describe the basay layer (stratum basale) of the epidermis?
Deepest layer, attached to the basement membrane, contains keratinocyte stem cells.
Also contains transient amplifying cells (TA) which are kind of like stem cells but divide a bunch and then become spinous cells.
Describe the stratum spinosum (spinous layer) of the epidermis?
Second deepest layer, composed of differentiating keratinocytes.
In most parts of the body it makes up most of the epidermis.
Synthesizes keratin.
*Spiney looking because of desmosome junctions*
What are the five types of junctions of the epidermis?
- Tight junctions: connection with actin
- Adherens junctions
- Desmosomes: contain keratins
- Focal adhesions
- Hemodesmosomes: one part of the desmosome
Describe the structure of keratin intermediate filaments?
They help connect cells
Describe the assembly of intermediate filaments?
Two rod domans of keratin form a heterodimer.
Two heterodimers form a tetramere.
Tetrameres lines up to form a protofilament, and several protofilaments becasue the intermediate filament.
What are the two types of granules in the stratum granulosum (granular layer)?
Keratohyalin granules and Lamellar granules (Odland bodies)
What are the keratohyalin granules in the stratum granulosum (granular layer)?
Filaggrin, involucrin, loricrin
What are the lamellar granules (odland bodies) in the stratum granulosum (granular layer)?
Tend to be made of fat.
Ceramides, cholesterol, fatty acids, hydrolytic enzymes
What are the characteristics of the stratum cornuem (cornified layer)? Where is it the thickest and thinnest?
Composed of corneocytes: lack nucleus and organelles (dead), held together by corneodesmosomes.
Primary barrier of the epidermis with variable thickness:
- No corneum in the ora, genital, and ocular mucosa
- Thinnest on the face and genetals
- Thickest on the palms and soles
What is keratinization?
The process of keratinocyte migration and maturation.
Average time is 28 days:
- stratum basale to stratum corneum > 14 days
- stratum corneum to shedding > 14 days
Describe the “bricks and mortar” concept of how keratinocytes turn into corneocytes?
The keratohyalin granules will form the cornified envelope (“bricks”) of the corneocyte for strength and shape.
The lamellar granules serve as the lipid envelope (mortar) around the corneocytes.
What is pemphigus vulgaris?
Acquired disease of the epidermis.
Autoimmune bullous disease involved auto-antibodies to desmosomal proteins (desmoglein 1 and 3). (desmosomes connect keratinocytes).
Results in intraepidermal blistering; just within the epidermis.
What are clinical features of pemphigus vulgaris?
- Flaccid, easily ruptured bullae
- Oral and mucosal lesions
- Nikolsky’s sign positive: rubbing on the skin by the blister causing it to shear off (pictured) due to loss of tight desmosomes holding it togehter
What is the treament for pemphigus vulgaris?
- Prednisone
- Azathioprine
- Mycophenolate mofetil
- Rituximab
What is Ichthyosis vulgaris? How common is it?
Autosomal dominant genetic condition
Mutations in profilaggrin gene that result in in a defective fillaggrin protein (this is what normally helps form the cornified later)
Affects 1 in 250
What are clinical features of ichthyosis vulgaris? What are some associations?
- “Fish scales” especially on the shins
- Dry skin
- Hyperlinear palms
Associations: atopic dermatitis, allergic rhinitis, food allergies, asthma.
Describe UV radiation? What are the different types?
UV radiation can be UVC, UVB, and UVA
UVC is filtered by the Ozone
UVA and UVB can penetrate our skin. UVB only goes to epidermis, UVA goes deeper into the dermis.
What is the main source of UV? What are characteristics of UV light?
The sun; the highest levels are from 10am to 4pm and at high altitudes.
UV light is not visible, and can penetrate clouds, water, and glas.s
What is the difference between physical sunscreen ingredients and chemical sunscreen ingredients?
Physical sunscreen ingredients: reflect and scatter UV light. Exp: titanium dioxide, zinc oxide.
Chemical sunscreen ingredients: absorb UV light. Exp. PABA, oxybenzone, avobenzone.
What is SPF?
Sun protective factor (SPF) = MED protected / MED unprotected.
MED = Minimal erythema dose = minimum amount of UVB that causes skin redness at 24 hours.
*SPF only measures UVB protection!
Is SPF 60 twice as effective as SPF 30? Describe the ideal sunscreen?
No, because the graph is exponential.
Ideal sunscreen: broad spectrum (UVA and UVB), water-resistant, SPF 30 or greater.
What are some sunscreen application tips?
Apply 15 minutes before sun exposure
Apply generously: 1 oz (shot glass) for adult; most people apply 25-50% of recommended dose)
Reapply every 2 hours, or every 40-80 is swimming/sweating.
Reaply after towel drying.
Describe a photoprotective regimen?
Sunscreens are only part of the regiment, avoid midday sun (10am-4pm)
Seek shade
Wear sun-protective hats/clothing.
What is the definition of SPF?
SPF = MED protected / MED unprotected
How would you describe a flat, nonpalpable primary lesion if it’s less than 1 cm? What if it’s >1 cm?
< 1 cm = macule
> 1 cm = patch
How would you describe a elevated or depressed, palpable primary lesion if it’s less than 1 cm? What if it’s >1 cm?
< 1 cm = papule
> 1 cm = plaque (differs from nodule because of broad and flat surface).
A nodule is palpable, > 1 cm, but differs from plaques in that it has a rounded surface
How would you describe a fluid-filled blister primary lesion if it’s less than 1 cm? What if it’s >1 cm? What about a pus-filled blister?
< 1 cm = vesicle
> 1 cm = bulla
Pus-filled = pustule
What is a wheal? What is it characteristic of?
Edematous papules and plaques that are characteristic of hives.
Describe telangiectasia, purpura, and petechia. How do they differ?
Telangiectasia: dilated blood vessels (go away if you press on them)
Purpura: area of hemorrhage; can be flat or elevated. Cannot make them go away with pressure.
Petechia: pinpoint purpura; can’t make go away with pressure.
What two questions does the primary lesion answer?
Can I feel this?
Is it more or less than a centimeter in size?
Describe these secondary changes/lesions: scale, crust, lichenification.
Scale: accumulation of stratum corneum
Crust: dried serum, pus, or blood
Lichenification: epidermal thickening with accentuation of skin markings (exp. chronic eczema)
Describe these secondary changes/lesions: excoriation, erosion, ulcer, fissure.
Excoriation: linear erosion caused by scratching
Erosion: open area with partial or full loss of epidermic
Ulcer: open area with loss of part of dermis
Fissure: linear ulcer
What shouldn’t be done when describing the color of a skin defect?
Do not use the word “erythematous” as it is not specific enough.
Use words like: link pink, brick red, hyperpigmented, hypopigmented, brown, tan, skin colored, violaceous, yellow-orange.
If you’re describing the configuration of a lesion, what does that mean?
The shape of an individual lesions or arrangement of multiple lesions.
Define the following configuration descriptors for skin lesions: nummular, geographic, and polycyclic.
Nummular: coin-shaped (more oval than round)
Geographic: Irregularly-bordered like a continent
Polycyclic: multiple round lesions coalesced together
Define the following configuration descriptors for skin lesions: serpiginous, annular, arcuate, and linear.
Serpiginous: wavy lines, worm-like
Annular: ring-like with central clearing
Arcuate: curved
Linear: straight line
Define the following configuration descriptors for skin lesions: targetoid, polygonal, reticulate or retiform, and stellate.
Targetoid: like a bulls-eye with at least 3 zones of color (annular only has 2)
Polygonal: resembling a polygon
Reticulate or retiform: net-like
Stellate: star-shaped
Define the following distribution descriptors for skin lesions: generalized, sun-exposed or photo-distributed, and acral.
Generalized: involving the entire body
Sun-exposed or photo-distributed: on places that are typically exposed to the sun
Acral: affecting distal limbs
Define the following distribution descriptors for skin lesions: blaschkoid, dermatomal, and symmatrical?
Blaschkoid: following Blaschko’s lines (exctodermal development lines)
Dermatomal: following skin areas supplied by a single spinal nerve
Symmetrical: equally affecting both sides of the body
Define the following distribution descriptors for skin lesions: unilateral and intertriginous?
Unilateral: affecting only one side of the body
Intertriginous: within body folds
What word means “warty”?
Verrucous.
