Moles, papules and tumours

Question 1

What are the functions of skin?

Answer 1

Sensation (touch, temperature, pain)
Thermoregulation
Metabolic function (synthesis of vitamin D)
Protection (against mechanical, chemical, osmotic and thermal stimuli; UV damage; microbial invasion)
Psychosocial (communication)

Question 2

What are the layers of the skin from superficial to deep?

Answer 2

Epidermis
Dermis - papillary region
Dermis - reticular region
Hypodermis (subcutis)

Question 3

What cell type makes up the epidermis?

Answer 3

Keratinised stratified squamous epithelium

Question 4

What are skin appendages?

Answer 4

Hair follicles, nails, sweat glands

Derived in epidermis and descend to the dermis during development

Question 5

What are the features of the dermis?

Answer 5

Bundles of collagen and elastin that give tone and texture to the skin (but degenerate with age)

Question 6

What are rete (interpapillary) pegs?

Answer 6

Projections of epithelial cells from the dermis into connective tissue

Question 7

What is the microscopic structure of the epidermis (from deep to superficial)?

Answer 7

Stratum basale (where mitosis of keratinocytes occurs) 
Stratum spinosum (keratinocytes joined by intracellular junctions called desmosomes) 
Stratum granulosum (lipids and waterproofing molecules secreted in this layer)
Stratum lucidum (cells lose nuclei and increase keratin production) 
Stratum corneum (cells lose nuclei and continue keratin production)

Question 8

How long does it typically take for maturation of a keratinocyte?

Answer 8

45-60 days

Question 9

How does keratinocyte maturation differ in psoriasis?

Answer 9

Drastically increased mitosis of keratinocytes causing thickened stratum spinosum giving characteristic ‘scaly’ skin

Question 10

What are the main types of skin cancer?

Answer 10

Basal cell carcinoma (most common)
Squamous cell carcinoma
Malignant melanoma (least common)

Question 11

How is prognosis for skin cancers (esp. melanoma) determined?

Answer 11

Depth of invasion through layers of skin (using Clark levels)
Can be level 1 (just affecting epidermis) through to level 5 (penetrating to subcutaneous tissue)

Question 12

What are the risk factors for developing a basal cell carcinoma?

Answer 12

UV radiation exposure
Immunosuppression
Inherited conditions (e.g. Xeroderma Pigmentosum, Gorlin’s Syndrome)

Question 13

What are the features of a basal cell carcinoma?

Answer 13

Slow-growing
Don’t generally metastasise
Locally destructive
Often located at sites with little surplus skin to repair the defect - can often require specialist surgery and extensive reconstruction

Question 14

What are the risk factors for developing a squamous cell carcinoma?

Answer 14

UV radiation exposure
Male sex
Fair skin
Occupational exposure (e.g. tars, oils, ionising radiation)
Immunosuppression

Question 15

What cellular and nuclear changes can indicate malignancy in cancers?

Answer 15

Hyperchromatism
Pleomorphism (altered shape of cells and nuclei)
High nuclear: cytoplasmic ratio
Loss of normal tissue architecture

Question 16

What are the types of flat skin lesions?

Answer 16

Macule (small lesion approx. <5mm)

Patch (larger lesion)

Question 17

What are the types of raised, solid skin lesions?

Answer 17

Papule (<5mm)
Nodule (>5mm)
Plaque (area greater than height)

Question 18

What are the types of raised, fluid filled lesions?

Answer 18

Vesicles (<5mm, clear serous fluid)
Bullae (>5mm, clear serous fluid)
Pustules (pus filled)

Question 19

What is a neoplasm?

Answer 19

Lesion (tumour) arising from the autonomous abnormal growth of cells that persist in the absence of an initiating stimulus. Can be benign or malignant.

Question 20

What features differentiate a malignant tumour from a benign tumour?

Answer 20

Malignant neoplasms have characteristics enabling them to invade surrounding tissue and spread to distant sites, such as:
Fast, invasive
Crab-like
No capsule
Tissue not resembling tissue of origin
Undifferentiated cells
Surface is irregular, may ulcerate and haemorrhage

Question 21

What are the possible types of melanocytic lesions?

Answer 21

Benign (e.g. moles/ naevi)
Borderline (dysplastic/ atypical)
Malignant (melanoma - in situ/ invasive)

Question 22

What macroscopic assessment can be done for melanocytic lesions?

Answer 22

ABCDE: 
Asymmetry 
Borders (irregular) 
Colour (uneven distribution/ more than one colour)
Diameter (>6mm) 
Evolution (?normal for your skin)

Question 23

What are the risk factors for development of a malignant melanoma?

Answer 23

UV radiation exposure
Personal/ family history of melanoma
Presence of dyplastic or abundant naevi

Question 24

What is the difference between an ‘in situ’ and an ‘invasive’ melanoma?

Answer 24

In situ = nests of abnormal melanocytes within the EPIDERMIS
Invasive = nests of abnormal melanocytes within the EPIDERMIS AND DERMIS

Question 25

How are the stages of cancer defined?

Answer 25

Stage refers to the size of a tumour and how far it has spread from where it originated

Question 26

How is the grade of a cancer defined?

Answer 26

Describes the appearance of cancerous cells

Question 27

What is TNM staging?

Answer 27

T = tumour (size, graded 1 to 4) 
N = nodes (extent of lymph node involvement, graded 0 to 2) 
M = metastases (distance to which tumour has metastasised, graded 0 to 2)

Question 28

What is an excision biopsy?

Answer 28

Ellipse shaped region around suspected cancer is removed from skin