Moles, papules and tumours Flashcards
What are the functions of skin?
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)
What are the layers of the skin from superficial to deep?
Epidermis
Dermis - papillary region
Dermis - reticular region
Hypodermis (subcutis)
What cell type makes up the epidermis?
Keratinised stratified squamous epithelium
What are skin appendages?
Hair follicles, nails, sweat glands
Derived in epidermis and descend to the dermis during development
What are the features of the dermis?
Bundles of collagen and elastin that give tone and texture to the skin (but degenerate with age)
What are rete (interpapillary) pegs?
Projections of epithelial cells from the dermis into connective tissue
What is the microscopic structure of the epidermis (from deep to superficial)?
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)
How long does it typically take for maturation of a keratinocyte?
45-60 days
How does keratinocyte maturation differ in psoriasis?
Drastically increased mitosis of keratinocytes causing thickened stratum spinosum giving characteristic ‘scaly’ skin
What are the main types of skin cancer?
Basal cell carcinoma (most common)
Squamous cell carcinoma
Malignant melanoma (least common)
How is prognosis for skin cancers (esp. melanoma) determined?
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)
What are the risk factors for developing a basal cell carcinoma?
UV radiation exposure
Immunosuppression
Inherited conditions (e.g. Xeroderma Pigmentosum, Gorlin’s Syndrome)
What are the features of a basal cell carcinoma?
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
What are the risk factors for developing a squamous cell carcinoma?
UV radiation exposure Male sex Fair skin Occupational exposure (e.g. tars, oils, ionising radiation) Immunosuppression
What cellular and nuclear changes can indicate malignancy in cancers?
Hyperchromatism
Pleomorphism (altered shape of cells and nuclei)
High nuclear: cytoplasmic ratio
Loss of normal tissue architecture
What are the types of flat skin lesions?
Macule (small lesion approx. <5mm)
Patch (larger lesion)
What are the types of raised, solid skin lesions?
Papule (<5mm)
Nodule (>5mm)
Plaque (area greater than height)
What are the types of raised, fluid filled lesions?
Vesicles (<5mm, clear serous fluid)
Bullae (>5mm, clear serous fluid)
Pustules (pus filled)
What is a neoplasm?
Lesion (tumour) arising from the autonomous abnormal growth of cells that persist in the absence of an initiating stimulus. Can be benign or malignant.
What features differentiate a malignant tumour from a benign tumour?
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
What are the possible types of melanocytic lesions?
Benign (e.g. moles/ naevi)
Borderline (dysplastic/ atypical)
Malignant (melanoma - in situ/ invasive)
What macroscopic assessment can be done for melanocytic lesions?
ABCDE: Asymmetry Borders (irregular) Colour (uneven distribution/ more than one colour) Diameter (>6mm) Evolution (?normal for your skin)
What are the risk factors for development of a malignant melanoma?
UV radiation exposure
Personal/ family history of melanoma
Presence of dyplastic or abundant naevi
What is the difference between an ‘in situ’ and an ‘invasive’ melanoma?
In situ = nests of abnormal melanocytes within the EPIDERMIS
Invasive = nests of abnormal melanocytes within the EPIDERMIS AND DERMIS
How are the stages of cancer defined?
Stage refers to the size of a tumour and how far it has spread from where it originated
How is the grade of a cancer defined?
Describes the appearance of cancerous cells
What is TNM staging?
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)
What is an excision biopsy?
Ellipse shaped region around suspected cancer is removed from skin
