Epidermis

Question 1

Layers of the epidermis:

Answer 1

Stratum basale
Stratum spinosum
Stratum granulosum
Stratum corneum

Question 2

Stratum basale:

Answer 2

Actively dividing stem cells along the basement membrane.

Contains keratinocyte stem cells - mitoses should be limited to this area.

Question 3

Stratum spinosum:

Answer 3

Differentiating keratinocytes, synthesize keratin.

Contains prominent desmosome attachments, makes up most of the epidermis.

Question 4

Stratum granulosum:

Answer 4

Composed of keratohyalin granules.

Question 5

Stratum corneum:

Answer 5

Corneocytes: anucleate cells with keratin. Site for superficial dermatophyte infections.

Held together by corneodesmosomes.

Variable thickness;
Thinnest: face, genitalia.
Thickest: palms, soles.
None: oral, genital, ocular mucosa.

Question 6

Keratinization length of time:

Answer 6

Average 28 days.

Question 7

Pemphigus vulgaris:

Answer 7

IgG antibodies against desmosomes (desmoglein 1 and 3) between keratinocytes (Type II HSR).

Vesicles and bullae develop on the skin and oral mucosa.

Nikolsky positive (outer epidermis separates from the basal layer with minimal pressure).

Treat with corticosteroids and other immunosuppressive agents.

Question 8

Ichthyosis vulgaris:

Answer 8

Autosomal dominant (most inherited skin disorder).

Mutations in profilaggrin gene (defect in keratinization, causes increased thickness of the stratum corneum, and absent stratum granulosum).

Hyperkeratotic, dry skin. Involves palms, soles, and extensor areas. Most commonly associated with atopic dermatitis.

Question 9

Minimal erythema dose:

Answer 9

minimal amount of UVB that causes skin redness at 24 hrs.

Question 10

SPF equation:

Answer 10

SPF = MEDprotected/MEDunprotected

**Only measures UVB protection.