Epidermis, dermis, subQ, and basement membrane zone (BMZ) Flashcards
Name the 4 layers of the epidermis from outermost to innermost
- Stratum corneum (cornified layer)
- Stratum lucidum (translucent layer) - **palms and soles only
- Stratum granulosum (granular layer)
- Stratum spinosum (spinous layer)
- Stratum basale (basal layer)
Name the contents of keratohyalin granules
- Filaggrin
- Involucrin
- Loricrin
Name the contents of lamellar granules
a.k.a. Odland bodies
- Ceramides
- Cholesterol
- Fatty acids
- Hydrolytic enzymes - responsible for sloughing of the corneal layer
Anuclear cells found in the uppermost layer of the epidermis are called what?
corneocytes
held together by corneodesmosomes
Where is the cornified layer thickest? Thinnest? What about mucosa?
- Palms, soles
- face, genitalia
- No cornified layer in oral, genital, and ocular mucosa
The process of keratinization takes on average how long?
28 days
Stratum basale to stratum corneum: 14 days
Stratum corneum to shedding: 14 days
The keratinocyte lipid envolope is derived from the contents of what? What about the cornified envelope?
- Lipid envelope: Lamellar granule (Odland body) -> outermost layer
- Cornified envelope: keratohyalin granule
Pemphigus vulgaris: describe
- mechanism
- presentation
- prognosis
- treatment
- Acquired autoimmune disease against Desmoglein 1 and 3 in the epidermis
- Fragile, flaccid, easily ruptured bullae (intraepidermal, Nikolsky’s sign positive), oral and mucosal lesions
- Poor. Often fatal if untreated
- Rx: prednisone, azathioprine, mycophenolate mofetil, rituximab
What is Nikolsky’s sign?
rubbing or applying pressure to a bulla increases its size
Seen in pemphigus vulgaris
Ichthyosis vulgaris: describe
- mechanism
- presentation
- Autosomal dominant genetic condition featuring defective filaggrin, leading to defective keratohyalin granules and improper formation of the corneal layer of the epidermis
- Extremely dry, fish-scale skin (ichtyotic, especially on shins), hyperlinear palms (more creases than usual). Associated with atopic dermatitis (eczema), allergic rhinitis, food allergies, and asthma
What is a physical sunscreen? Give a couple examples.
Physical sunscreen reflects or scatters UV light
titanium dioxide, zinc oxide
What is a chemical sunscreen? Give a couple examples.
Chemical sunscreen absorbs UV light.
PABA, oxybenzone, avobenzone
What is MED?
Minimal erythema dose: minimum amount of UVB that causes skin redness at 24 hours.
Define: SPF
Sun protection factor (SPF)
SPF = MEDprotected/MEDunprotected
Does SPF60 provide 2x the protection of SPF30?
No, despite what the formula would otherwise imply.
Describe:
- UVA
- UVB
- UVC
- 320-400nm - mostly responsible for tanning and photoaging
- 280-320nm - mostly responsible for ertythema and sunburn
- 200-280nm - most is absorbed by the atmosphere
The dermis is embryologically derived from what?
mesoderm
Describe in terms of cellularity and collagen content:
- Papillary dermis
- Reticular dermis
- higher cellularity, loose collagen
- lower cellularity, denser collagen
What is the most abundant collagen type in the dermis?
Collagen type I
What is the second most abundant type of collagen, involved in wound healing and embyrogenesis?
Collagen type III
Give location and function:
- Meissner’s corpuscles
- Pacinian corpuscles
- superficial dermis (papillary), responsible for light touch
- deep dermis, found in greater density on weight-bearing surfaces, lips, nipples, penis, clitoris. Responsible for deep pressure sensation.
Marfan’s Sydrome:
- Etiology
- presentation
- autosomal dominant genetic defect in fibrillin, variable expression
- Stria, long limbs and fingers, hyperflexible joints, pectus excavatum, aortic anyeurism, mitral valve prolapse, dislocated lens (ectopia lentis), nearsightedness (myopia), scoliosis
Ehlers-Danlos Syndome:
- Etiology
- Presentation
- Group of inherited connective tissue disorders with abnormalities in collagen production, processing, or assembly. Variable inheritance and clinical features
- Fragile/elastic skin, hyperflexibility of joints, scoliosis, dislocations, arthritis
Morphea:
- Etiology
- Presentation
localized scleroderma
- Autoimmune disease causing sclerosis (thickening of collagen)
- F > M; violaceous plaques, progressing to sclerotic plauqes with scarring. Usually little systemic involvement. May also show limb contractures and atrophy, or neurologic disorders (due to contractures over the head).
Systemic sclerosis:
- Etiology
- Presentation
systemic scleroderma - very similar to Morphea, but not localized
- Autoimmune disease
- Primarily affects middle-aged women. Shows widespread sclerosis, leading to microstomia, sclerodactyly, Raynaud’s phenomenon, telangiectasia, and arthritis. May involve organs: pulmonary fibrosis, renal crisis, esophageal dysmotility.
subcutaneous fat is derived from what embryological layer?
mesoderm
What is panniculitis?
Inflammation of subcutaneous fat
Erythema nodosum:
- Etiology
- Presentation
Reactive panniculities
- panniculitis triggered by streptococcal pharyngitis, oral contraceptives, irritable bowel disease, and malignancy. Affects primarily young women.
- Tender red nodules on shins (hard lumps), with active inflammation of the subcutaneous fat (seen histologically)
Name the four layers of the BMZ
- hemidesmosome
- lamina lucida
- lamina densa
- sublamina densa
Describe BP230
a.k.a. bullous pemphigoid antigen 1 (BPA-1)
- cytoplasmic
- responsible for organization of the cytoskeletal structure
Describe BP180
a.k.a. bulloud pemphigoid antigen 2 (BPA-2) a.k.a. collagen XVII
- transmembrane protein connecting basal keratinocytes through BP230 (BPA-1) to the cytoskeleton
- Also connects to dermal collagen VII through laminin 332
Bullous pemphigoid:
- Etiology, epidemiology
- Presentation
- DIF
- IIF
- Prognosis
- Treatment
- Antibody against BPA-1 (BP230) and BPA-2 (BP180) resulting in subepidermal blisters. Affects primarily the elderly.
- Pruritis urticaria without blisters, progressing to tense, serous (hemorrhagic rare) blisters. Blisters are tense/strong because the blistering involves the entire epidermis (separate at dermis/epidermis interface i.e. at BMZ)
- DIF: linear IgG and C3 along BMZ
- IIF: epidermal-sided linear stain
- better than pemphigus vulgaris (flaccid blisters)
- high-potency steroids (caution with elderly patient population)
GABEB: Generalized Atrophic Benign Epidermolysis Bullosa
- Etiology
- Presentation
- Inherited mutation in BP180 (BPA-2)
- Generalized blistering, atrophic scarring, nail dystrophy. Presents at birth.
Mucous Membrane Pemphigoid:
- Epidemiology/etiology
- Presentation
- DIF
- IIF
5.
- Predominantly affects elderly. Antibodies against BP180. Some patients have antibodies targeting BP230, integrin beta-4, and laminin 332 (AECP, associated with malignancy).
- Recurrent blistering of the mucous membranes and skin. Develop scars, strictures, synechiae, blindness (20%).
- Linear IgG and C3 deposits along BMZ
- Linear staining epidermal or epidermal and dermal. Laminin 332 MMP (AECP - anti-epiligrin cicatrical pemphigoid) shows on dermal side only.
Herlitz Juntional EB:
- Etiology
- Prognosis
- laminin 332 mutation
- very high mortality
Name the genetic (congenital) and autoimmune (acquired) bulloud disorders associated with each of the following:
- Desmoglein 1, 3
- Keratins 5, 14
- BP230
- alpha-6-beta-4 integrins
- BP180 (type XVII collagen)
- Laminin 332
- Type VII collagen
- striate palmoplanar keratoderma (congenital), pemphigus vulgaris (acquired)
- epidermolysis bullosa simplex (congenital)
- Bulloud pemphigoid (acquired)
- Epidermolysis bullosa with pyloric atresia (congenital), bulloud pemphigoid (acquired)
- Non-Herlitz epidermolysis bullosa (congenital), Bullous pemphigoid, mucous membrane pemphigoid, linear IgA disease (acquired)
- Herlitz epidermolysis bullosa (congenital), mucous membrane pemphigoid (acquired)
- Dominant/recessive dystrophic epidermolysis bullosa (congenital), epidermolysis bullosa acquisata (acquired)
Epidermolysis Bullosa Acquisata (EBA):
- Epidemiology
- Presentation
- DIF
- IIF
- Acquired autoimmune disease. Antibody against type VII collagen (in the sublamina densa)
- Slight trauma elicits blistering and erosions. Mechanically-stressed areas also show blistering and erosions (hands, feet, elbows, knees, oral mucosa, nails.
- Linear staining IgG and C3 in BMZ
- Dermal side
Epidermolysis Bullosa:
- Etiology
- Presentation
- Types and targets
- Skin fragility disorders resulting from inherited mutations in genes encoding BMZ proteins.
- Blisters and erosions from minimal mechanical trauma. Variable features depending on type
- Types:
- Epidermolysis bullosa simplex: autosomal dominant, targets keratins 5, 14 in basal keratinocytes
- Junctional EB - autosomal recessive, targeting laminin 332 and BP180
- Dystrophic EB - autosomal dominant or recessive, targeting type VII collagen
Stratum lucidum (of the epidermis) is only found where?
acral skin (palms and soles)
Where are melanocytes typicall found? How many of them are generally present?
Basal layer of epidermis
Typically 1:10 (melanocytes:keratinocytes)
What are Langherhans cells?
Dendritic APCs in the epidermis
The papillary and reticular layers of the dermis are delineated by what? Describe the collagen in each layer.
- Delineated by a vascular plexus
- Papillar: fine, vertical collagen
- Reticular: coarse, horizontal collaged
What touch sensor type is found in the deep dermis/subQ interface of the palms, soles, digits, genitalia, ligaments, and joints and senses deep pressure/vibration?
Pacinian corpuscles
Name the (3) parts of the hair follicle and what delineates them
- Infundibulum: follicular orifice to entrance of sebaceous duct
- Isthmus: sebaceous duct to insertion of arrector pili muscle
- Lower portion: below insertion of arrector pili muscle
Sebaceous glands use what type of secretion? Where can they be found?
Holocrine secretion
Eyelids, vermillion border of lips, penis, nipple
What type of sweat gland is usually activated at puberty? Describe them.
Apocrine glands
Typically opens into the hair follicle at the level of the sebaceous gland.
Found in axillae, anogenital area, external ear canal, eyelid, and areola
Decapitation secretion
What sweat gland type is found over virtually the entire body, but is especially concentrated in the plams, soles, axillae, and forehead? Where do they generally empty?
Eccrine
Empty directly to the skin surface
Describe the unique features of skin found in each of the following locations:
- scalp
- trunk
- eyelid
- nose
- ear
- acral
- mucosa
- scalp: many large terminal hairs, with hair bulbs extending into subQ fat
- trunk: very thick with broad parallel collagen fascicles in dermis
- eyelids: Very thin, skeletal muscle bundles, hair follicles
- nose: conspicuous sebaceous glands that often drain directly onto the skin surface
- ear: vellous hair follicles and prominent cartilage
- acral skin: thick, compact stratum corneum with prominent rete ridge pattern (fingerprints), stratum lucidum is present
- mucosa: No granular layer present. Pale keratinocytes due to glycogen content
