Histology

Question 1

Where is inflammatory infiltrate seen in acute dermatitis?

Answer 1

In the upper dermis

Question 2

Describe inflammatory infiltrate in acute dermatitis

Answer 2

Groups of purple cells which will be lymphocytes, seen in the upper dermis

Question 3

Where is the main abnormality in acute dermatitis and what is seen?

Answer 3

Main abnormality is in the epidermis where bubble-like structures will be seen. These represent fluid collections and would clinically be seen as tiny blisters

Question 4

Spongiosis

Answer 4

Fluid accumulation between the keratinocytes in the epidermis

Question 5

True or false: spongiosis is the typical histological pattern seen in acute dermatitis

Answer 5

True

Question 6

Epidermis in psoriasis

Answer 6

Thickened epidermis and lots of keratin in the keratin layer which is loosely packed, with the accumulation of inflammatory cells, particularly neutrophils

Question 7

Where are nuclei normally broken down?

Answer 7

Granular layer

Question 8

Parakeratosis

Answer 8

Retention of nuclei

Question 9

In which condition is parakeratosis present and why?

Answer 9

Psoriasis due to rapid and abnormal differentiation of keratinocytes

Question 10

Describe rete pegs in psoriasis

Answer 10

They are thicker and longer and often joined together

Question 11

Histology of bullous pemphigoid

Answer 11

Epidermis splits up off the dermis at the dermo-epithelial junction so the whole of the epidermis forms the roof of the blister. If split is higher up then the roof is thinner and blister bursts more easily
Inflammatory cells within the blister – mostly eosinophils

Question 12

Toxic dermal necrolysis is drug induced - true or false?

Answer 12

True

Question 13

What type of cell dies in toxic dermal necrolysis?

Answer 13

Keratinocyte

Question 14

Mortality rate with toxic dermal necrolysis?

Answer 14

25-40%

Question 15

What does toxic dermal necrolysis result in?

Answer 15

Epidermal detachment from dermo-epidermal junction

Question 16

What can skin failure lead to?

Answer 16

Loss of thermoregulation, increased risk of infection, failure of homeostatic function

Question 17

Things required for healthy skin

Answer 17

Intact physical barrier
Functioning immune system
Functional vasculature
Functioning venous return and lymphatic system
Means of temperature regulation
Normal sensory nerve function to warn us about injury
Adequate nutrition

Question 18

Means of temperature regulation in healthy skin

Answer 18

Capillary dilation/constriction, functioning sweat glands

Question 19

What is a wound?

Answer 19

Any break in the skin

Question 20

What does the method of wound healing depend on?

Answer 20

Size and type of wound

Question 21

How do most surgical wounds heal?

Answer 21

Primary intention

Question 22

Primary intention healing

Answer 22

Edges approximated by stitches leading to rapid healing

Question 23

How can primary intention healing be compromised?

Answer 23

Haematoma, infection, poor suture technique, dehiscence

Question 24

What type of wounds is secondary intention healing used for?

Answer 24

Larger wounds that are too tight to stitch or where direct closure would cause significant distortion of surrounding tissues

Question 25

3 stages of secondary intention healing

Answer 25

1 = inflammation
2 = proliferation
3 = tissue remodelling

Question 26

What happens in inflammation stage of secondary intention healing?

Answer 26

Platelets form an initial clot and release inflammatory mediators.
Leucocytes debride the wound bed by phagocytosing bacteria and scavenging cellular debris
Inflammation gradually decreases and keratinocyte proliferation and new tissue formation becomes predominant

Question 27

What happens in proliferation stage of secondary intention healing?

Answer 27

Cells proliferate to re-epithelialise the wound surface
Granulation tissue formation is stimulated
Fibroblasts lay down matrix and contract the wound (fibroplasia)
Endothelial cells develop new blood vessels (angiogenesis)

Question 28

What happens in tissue remodelling stage of secondary intention healing?

Answer 28

New tissue is converted into mature scar tissue over a period of months
Fibroblasts lay down collagen to improve the tensile strength of the scar and restore the dermal matrix

Question 29

Superficial burns are erythematous/non-erythermatous, wet/dry and non-painful/painful

Answer 29

Superficial burns are erythematous, wet and painful

Question 30

What colour are deep burns?

Answer 30

White or black and charred

Question 31

Are deep burns wet or dry?

Answer 31

Dry

Question 32

Are deep burns painful?

Answer 32

No, they are numb

Question 33

Where do the burns extend in:

• First degree?
• Second degree/partial thickness?
• Third degree/full thickness?

Answer 33

First degree = epidermis only
Second degree/partial thickness = epidermis and dermis
Third degree/full thickness = beyond dermis

Question 34

What are chronic wounds?

Answer 34

Wounds present >6 weeks

Question 35

What do chronic wounds often exhibit?

Answer 35

Surface slough

Question 36

What is surface slough?

Answer 36

A mixture of dead cells, polymorphs and bacteria. It is a yellow/green colour

Question 37

Effect of slough on healing of wounds

Answer 37

Inhibitory effect on healing ability of wound

Question 38

How can slough be removed?

Answer 38

Chemically, with physical debridement or larval therapy

Question 39

Where do chronic wounds tend to heal from?

Answer 39

The edges - increased risk of infection

Question 40

Factors that contribute to delayed healing of wounds

Answer 40

Infection
Poor arterial supply
Impaired venous return
Repeated trauma/friction
Poor nutritional state
Underlying systemic disease

Question 41

Factors leading to breakdown of skin: erosion and ulceration (relating to pressure sores)

Answer 41

Prolonged pressure over a bony area
Lack of blood flow
Friction from bedding/clothing
Irritation from sweat/blood/urine/faeces

Question 42

Stages of development of pressure sores

Answer 42

• Skin is unbroken but shows a pink or reddened area. May look like a mild sunburn. Skin may be tender, itchy or painful
• Skin is red, swollen and painful. Blisters (broken or intact) may be present. Upper layers of skin begin to die
• Sore has broken through the skin and wound extends down to deeper layers of the skin tissue. Crater-like ulcers are present. Wound is prone to infection
• Sore extends past the skin and into fat, muscle and bone tissue. Blackened, dead tissue called eschar may be seen in deep opened wounds