Epidermis and Disorders of Keratinization

Question 1

What are the Lines of Blaschko?

Answer 1

during embyogenesis, karetinocytes migrate from the dorsal neural crest tower the anterior midline of the skin and distally to the extremities in a pattern distinct from dermatomes (dermatomes respect the midline)

Question 2

What are the four layers of the epidermis?

Answer 2

basal layer, spinous layer, granular layer and cornified layer

Question 3

Basal layer (stratum basale) is linked to the dermis via what?

Answer 3

hemidesmosomes

Question 4

In the spinous layer (stratum spinosum) adjacent karatinocytes connect via _____. What immune cells would you expect to see in this layer?

Answer 4

desmosomes, Langerhans cells

Question 5

_______ are a protein that link desmosomes inter cellularly. (type 1 has higher concentration in upper epidermis and type 3 is located in the basal layer)

Answer 5

Desmogleins (disfunction can lead to pemphigus vulgarism if in the basal layer)

Question 6

Granular layer (stratum granulosum) is characterized by granules that contain what?

Answer 6

karatohylaline granules (proflaggrin promotes aggregation and stabilization of intermediate filaments in the cornified layer) and lamellar granules (lipids and hydrolyses are released at the stratum corneum to create a hydrophobic barrier)

Question 7

The cornified layer (stratum corneum) releases ____ ____ ___ like free amino acids, lactic acid or urea that are hygroscopic (retain water)

Answer 7

natural moisturizing factors

Question 8

Diseases that affect karatinocytes can affect any of the 4 process included in keratinization, which includes: ?

Answer 8

apoptosis, degradation of cellular organelles, formation of lamellar granules and karatohyaline granules (flaggrin-induced keratin filament assembly and cross linking and release of lamellar granules) and enlargement and flattening of karatinocytes

Question 9

Descquamation occurs through _____ of intercellular bonds via action of hydroslases. Normally keratinocytes shed singly.

Answer 9

hydrolases

Question 10

What happens when the process of desquamation is altered?

Answer 10

xerosis (dry skin)

Question 11

How is xerosis characterized and what causes it?

Answer 11

characterized by fine, white scale, hyperkeratosis, sometimes itchy
causes are dehydration of keratinocytes (decrease in NMF or intercellular lipids) or failure to break the intercellular bonds in an organized fashion

Question 12

What are exogenous and endogenous things that contribute to xerosis?

Answer 12

exogenous: dry climate (forced air), excessive exposure to water (hand washing) and exposure to detergents
endogenous: atopy, ichthyosis vulgarism, renal insufficiency, lipid lowering medications, malnutrition

Question 13

Hyperplasia of the stratum spinosum is called _____, an increased rate of cell turnover and inflammation, and it can lead to the disease ______.

Answer 13

acanthosis leading to psoriasis

Question 14

A type of hyperplasia of the stratum corneum is termed ______, abnormal retention of karatinocytes, and it can lead to a disease called ______.

Answer 14

hyperkeratosis leading to keratosis pilaris (accumulation of keratinocytes around the hair follicles)

Question 15

Hyperplasia in the stratum spinososum and the stratum corneum can be caused by rubbing and scratching which can lead to a condition ____ _____ _____.

Answer 15

lichen simplex chronicus

Question 16

Describe the “bricks and motor” model of disorders of cornification.

Answer 16

disorders can arise due to karatinocytes cross-linking with intermediate filaments (bricks) or with issues with the intercellular lipids (mortar).

example: lamellar ichtheosis is due to defective keratinization while harlequin ichthyosis is due to a defective lipid barrier

Question 17

Describe the clinical presentation and associated findings of ichthyosis vulgaris.

Answer 17

ichtyosis vulgarism is the most common disorder of cornification, caused by an autosomal dominant trait with variable expression. clinical presentation is classic “fish scale” appearance. associated findings are asthma, eczema, allergic rhinitis, keratosis pilaris and hyper linear palms

Question 18

Describe the presentation of keratooderma and its 3 variations.

Answer 18

keratoderma is a family of dominantly inherited diseases characterized by hyperkeratosis, most commonly of he palms and soles (treatments with topical moisturizers and humectants)

subtypes:
diffuse: thick, yellow plaques on plasm/soles, associated with hyperhidrosis
focal: hyperkeratosis over pressure points
punctate: hyperkeratotic papules with a warty appearance

Question 19

List 3 diseases characterized by altered epidermis.

Answer 19

atopic dermatitis, psoriasis and staphylococcal scalded skin syndrome

Question 20

Describe the clinical presentation of atopic dermatitis

Answer 20

(aka ezema) an inflammatory disease that includes an aberrant TH2 response (barrier disruption due to a filaggrin defect can predispose patients). patient will complain of pruritic rash that favors flexural surfaces (may lead to secondary infection) and present with irregular erythmatous patches

Question 21

Describe the clinical presentation of psoriasis.

Answer 21

patient presents with red plaques, thick and adherent scale and nail changes particularly on extensor surfaces which may be itchy or be accompanied by arthralgias (joint pain), an inflammatory disease that is mediated by TH1 and TH17 response causing a faster cell turnover rate

Question 22

Describe the clinical presentation of staphylococcal scaled skin syndrome.

Answer 22

cutaneous erythema starts at head and generalizes, accompanied by flaccid bullae, desquamation over 3-5 days with extreme skin tenderness/pain and a prodrome of malaise, irritability and fever. caused by staph aureus exotoxin exfoliative toxin a and B that target desmoglein 1 and lead to loss of cell-cell adhesion

**because toxins are renal excreted patients that are younger than 6 yo and patients in renal failure and immunosuppresion have an increased risk for this disease

Question 23

Where would you culture to support a diagnosis of SSSS

Answer 23

culture of the nasopharynx or conjunctivae or purulent skin lesions, cultures from bullae are negative.

Question 24

Suggest 5 recommendations for caring for dry skin.

Answer 24

avoid hot showers and prolonged soaking
use mild soaps or soapless cleansers
avoid products with fragrances
pat dry with a towel and apply emollients after bathing
use humidifiers during winter months

Question 25

Contrast emollients and humectants.

Answer 25

emollients are moisturizes including lotions, creams and ointments which protect and moisture to the skin while humectants can pull water into cells using ammonium lactate or urea (best for severely dry skin)