Dermatology

Question 1

Describe the structure of the skin

Answer 1

Epidermis:
-outer layer of skin
-no blood supply
-stratum corneum, granulosum, spinosum, basale
Dermis:
-hicker inner portion w/loose CT
-superficial region: around the dermal papillae- capillaries, meissner’s corpuscles, free nerve endings, sebaceous glands, arrector pilli muscle
-deeper region: reticular dermis- layer of dense irregular CT- collagen and elastin
-fibroblasts, macrophages + fat cells
Hypodermis: merges w/dermis- mainly adipose tissue

Question 2

What is the dermal papillae

Answer 2

areas where the dermis extends into the epidermis- helps adhesion between the two layers
-on the palms and soles, these appear as papillary ridges

Question 3

Where is the epidermis thicker- relevance to pt treatment

Answer 3

• thicker on palms and soles compared to axillaie and flexual creases
• relevance to derm: for certain topical creams such as steroid creams used for eczema- strong steroids will be used in areas where skin is thicker

Question 4

How do keratinocytes migrate to the skin surface

Answer 4

-epidermal stem cells are in the basal layer and are attached to the basement membrane through hemidesmosomes
-Epidermal stem cells divide in a random manner yielding either more stem cells or transit amplifying cells.
- the transit amplifying cells continue to proliferate then commit to differentiate and migrate towards the surface of the epidermis.
-Those stem cells and their differentiated progeny are organized into columns named epidermal proliferation units.
-During this differentiation process, keratinocytes permanently withdraw from the cell cycle, initiate expression of epidermal differentiation markers, and move suprabasally as they become part of the stratum spinosum, stratum granulosum, and eventually corneocytes in the stratum corneum.
Corneocytes are keratinocytes that have completed their differentiation program and have lost their nucleus and cytoplasmic organelles. Corneocytes will eventually be shed off through desquamation as new ones come in.

Question 5

functions of the skin

Answer 5

• protection: chemical, thermal, physical, UV
• thermoregulation
• neuroreceptors- pick up on external stimuli- sensation- pain, touch, pressure, temperature
• synthesis of vitamin D and triglycerides
• antigen processing: langerhaan skills- fight off infection but may also be involved in development of contact allergies

Question 6

how does the skin regulate temperature

Answer 6

• has a complex vascular network that can shunt skin to or away from the surface to lose of conserve heat

Question 7

important factors to

consider in the history and examination of a patient

Answer 7

-age
-HPC
-current/ past treatments
-family history
-drug history
-allergies- ESP PENICILLIN
- examine skin properly- inc. hidden areas and mucous membranes
-look at the:
> site: localised/ generalised/ cutaneous/ mucocutaneous/ affecting only mm’s
> morphology- mono/ polymorphic, blister/ erosion/ scarring
> background skin: normal vs erythema

Question 8

list and desribe the primary lesions (clue: there are 9)

Answer 8

macule: a flat circumscribed lesion < 1cm dia.
patch: a flat circumscribed lesion > 1cm dia.
plaque: flat topped, raised lesion > 1cm dia.
papule: palpable, circumscribed elevation < 1cm dia.
nodule: palpable, circumscribed elevation > 1cm dia.
vesicle: blister containing fluid <0.5cm dia.
bulla: blister > 0.5cm dia.
wheal: transient red/pink swelling of the skin with central pallor
telangiectasia: dilation of capillaries

Question 9

list and describe the secondary lesions (clue: there are 7)

Answer 9

crust: dried exudate- serous, purulent, haemorrhagic
excoriation: shallow haemorrhagic excavation resulting from scratching- linear/ discrete
lichenification: