Skin Cancer Flashcards
What two distinct pathways converge to cause skin cancer?
Direct action of UV on target cells (kertatinocytes) for neoplastic transformation via DNA damage (e.g. p53 mutation)
Effects of UV on the host’s immune system
What are the three main skin cancer types?
Basal cell carcinoma
Squamous cell carcinoma
Malignant melanoma
From most superficial to the most deep, list the three skin cancer types.
Squamous cell carcinoma
Basal cell carcinoma
Malignant melanoma
What is the most common type of skin cancer?
Basal cell carcinoma
Describe the pathophysiology of basal-cell carcinoma.
Basal cells control the process of creating new skin cells
A mutation in the DNA of basal cells causes a basal cell to mutliply and grow rapidly when it would normally die.
Eventually the accumulating abnormal cells may form a tumour.
Is there a genetic risk for basal cells carcinoma?
PTCH gene mutation may predispose a person to this
Were are basal cell carcinomas most commonly found?
80% are found on the head and neck
- UV exposed sites
How common is basal cell carcinoma?
30% of Caucasians will develop a basal cell carcinoma
List the basal cell carcinoma subtypes.
Nodular - most common
Superficial
Pigmented
Morphoeic/sclerotic
Describe the appearance of a nodular basal cell carcinoma.
Nodule (greater tha 0.5cm raised lesion)
Shiny - reflects light
Telangectasia - fine, broken blood vessels
Often central ulceration - the top layer of the dermis has come away
- more likely to bleed
Smooth edges
Describe the appearance of a superficial basal cell carcinoma.
Doesn't have a nodular texture - smoother Telangectasia on microscopy Shiny Small amount of ulceration Quite dry
Describe the appearance of a pigmented basal cell carcinoma.
Ulceration Telangectasia On a sun exposed site Well demarcated, lumpy egde Shiny
What is the differential diagnosis of a pigmented basal cell carcinoma?
Pigmented lesion
Mole
Melanoma
- need to check with a biopsy
Describe the appearance of a morphoeic/sclerotic basal cell carcinoma.
Very similar to normal skin Shiny on flash Well demarcated Telangectasia Central area of depression Slightly raised edge
List the available treatments for basal cell carcinomas.
Surgical excision - gold standard - 3-4mm margin to account for infiltration Curettage and cautery Cryotherapy Photodynamic therapy Topical imiquimod/5-fluorouracil cream Mohs micrographic surgery
Describe curettage and cautery in skin cancer treatment.
Circular scalp instrument is used to scoop away the malignant skin. Cautery is used to burn away any remaining malignant cells
- less accurate as you have to guess the penetration of the cancer
- used in more elderly patients
What is cryotherapy in skin cancer treatment?
Lquid nitrogen is sprayed onto the affected area, and the cancer is frozen off
- no margin control
- sore and causes blistering
Describe topical imiquimod or 5-fluorouracil cream in skin cancer treatment?
These stimulate the immune reaction in tumour cells, which attracts the attention of the immune system
- works best in superficial BCC
Describe Mohs micrographic surgery in skin cancer treatment.
Frozen section technique
- can tell you immediatly whether you have excised all the malignant cells
When does squamous cell carcinoma occur?
Normal skin
Injured skin - burns
- most SCC occur on skin regularly exposed to UV radiation
Chronically inflamed
Which cells mutate to cause squamous cell carcinoma?
Keratinocytes
What is the second most common skin cancer?
Squamous cell carcinoma
What are the pre-malignant variants to squamous cell carcinoma?
Actinic keratoses
Bowens disease
What is the risk of metastasis of SCC?
From a high risk SCC (on ears, lips)
- 10-30%
Describe the appearance of a squamous cell carcinoma tumour.
Less shiny More ragged edges Hyperkeratinosis Crusty No/little ulceration
List the treatments for squamous cell carcinomas.
Surgical excision (larger margin than for BCC - 4mm) Curettage and cautery Topical imiquimod/5-fluorouracil cream Cryotherapy Photodynamic therapy Sun protection
Describe malignant melanoma.
Malignant tumour of melanocytes
- most common in the skin, but can be found in the bowel and eye
DNA damage caused by UV light (genetic mutations are rare)
Radial growth phase followed by vertical growth phase
How is the prognosis of melanoma determined?
Depth of presentation and metastasis
What is the name of the pre-malignant form of melanoma?
Melanoma in situ
Where does melanoma commonly metastasise to?
To the local draining lymph nodes
- melanoma is spread via the lymphatics
List some of the risk factors for the development of melanoma.
Genetic markers (CDKN2A mutations) UV irradiation Sunburns during childhood Intermittent burning exposure in unacclimatised fair skin Number and size of melanocytic nevi Number of atypical nevi High socioeconomic status Skin types I or II DNA repair defects Immunosupression - no immune system to protect against cancer
What is the Clark’s level?
Tells you what depth of the skin the melanoma has reached
What depths of the skin will the melanoma have reached in Clark’s level 1-5?
1 - epidermis 2 - superficial half of the papillary dermis 3 - deep half of the papillary dermis 4 - Reticular dermis 5 - Subcutaneous tissue
What is the 10 year survival for melanoma at all of the Clark’s levels?
1 - normal 2 - 93% 3 - 71% 4 - 59% 5 - 36%
List the melanoma subtypes.
Superficial spreading malignant melanoma - most common Nodular melanoma Acral melanoma (hands, feet and nails) Subungal melanoma (underneath nails) Amelanotic melanoma - looks like a BCC Lentigo maligna Lentigo maligna melanoma (invasive version) Melanoma-in-situ
Describe the appearance of an acral melanoma.
Late presenting - people don’t look at their feet
Irregular shape
Irregular colour
Callus formation
Satellite tumours away from the original tumour
What feature of subungal melanoma indicates a high severity?
Hutichisons signs
- pigment from the nail is spilling onto the skin
- be aware of pseudo-hutichisons sign (reflection of pigment from the nail onto the skin)
How can you tell the difference between an amelanotic melanoma and granuloma tissue?
Amelanotic melanoma has a more chronic history
- has been kicking around for a long time
What is the treatment for melanoma?
Surgical excision - 1/2cm margin
Chemotherapy (if metastatic) - isolated limb perfusion to prevent systemic effects of chemo
Vaccine therapy
Biologic antibodies to vascular growth factors (bevacizumab) or BRAF genetic defects (vemurafenib)
Assessment for lymph node/organ spread
List the cutaneous tumour syndromes.
Gorlin’s syndrome
- multiple BCCs, jaw cysts and increased risk of breast cancer
Brook Spiegler syndrome
- multiple BCCs, trichoepitheliomas
Gardner’s syndrome
- soft tissue tumours, polyps, bowel cancer
Cowden’s syndrome
- multiple hamartomas, thyroid and breast cancer
Describe the appearance of superficial spreading melanoma.
Flat/smooth Dark brown patch of skin Superficial Irregular edge Often a precursor to malignancy
Describe the appearance and presentation of nodular melanoma.
Presents as a rapidly enlarging lump (weeks -> months) Larger size than moles (6mm - 10mm) Dome-shaped Symmetrical Firm Pigmented - red, black, brown Smooth, rough, crusted or warty surface Itchy
Describe the appearance of lentigo maligna and lentigo maligna melanoma.
Presents as a slowly growing or changing patch of discoloured skin - can grow to several cm in size over a few years Irregular shape Variable pigmentation Smooth surface Melanoma - thickening - increasing number of colours - ulceration - itching
