Skin cancers Flashcards
What are the layers of human skin?
Photo
What is the structure of the epidermis?
Made up of four cell types: keratinocytes, melanocytes, Merkel cells (or tactile cells) and dendritic cells. Keratinocytes proliferate in the stratum basale and migrate up and mature: they ascend through the stratum spinosum (spinous keratinocytes), granulosum (granular keratinocytes), lucidum and corneum where they flake. Keratinocytes are found closest to the skin surface, so are most susceptible to damage from UV radiation.
What is the relative contribution of each UV radiation type to skin cancer?
UVB is the most important wavelength in skin carcinogenesis; 100x more UVA reaches the Earth’s surface than UVB but is not the most important contributor to skin carcinogenesis.
What is basal cell carcinoma?
Malignant tumour arising from keratinocytes in the basal layer of epidermis. AKA rodent ulcer.
What is the aetiology of basal cell carcinoma?
Sun exposure and UV radiation leading to DNA damage
What are the risk factors of basal cell carcinoma? (x2)
- Associated with conditions relating to abnormalities in the patched/hedgehog intracellular signalling cascade (important in embryonic stem cell differentiation) such as Gorlin-Goltz syndrome
- Pitch (a resin), tar and arsenic exposure
What is the pathophysiology of basal cell carcinoma?
Neoplastic basal cells (originating from the basal layer of the EPIDERMIS) aggregate to form well-defined neoplastic ‘nests’. The outer cells arrange into palisades (on the edges of the neoplastic nests, nuclei of malignant cells are arranged in a manner similar to a fence), invade the dermis, and apoptotic bodies can be seen (vesicles of packaged apoptotic cell). It is slow-growing and invades tissue but rarely metastasises.
What is the epidemiology of basal cell carcinoma: Common? Ethnicity? Age?
The most common form of skin cancer. Most common in white ethnicities. Rare before age of 40.
What are the signs and symptoms of basal cell carcinoma? Where?
Common on the face. Pearly (glistens, pink-grey colour) with telangiectasia. Slow growing
What are the different types of BCC? (x4)
- NODULO-ULCERATIVE (most common): the classic ‘rodent ulcer’ which is characterised by a central ulcer and raised pearly edges OR it can present as small glistening translucent skin over a coloured papule which slowly enlarges. Telangiectatic vessels run over the tumour in both presentations
- MORPHOEIC: expanding, yellow/white waxy plaque with an ill-defined edge
- SUPERFICIAL: most often on trunk, multiple pink/brown scaly plaques with fine ‘whipcord’ edge expanding slowly
- PIGMENTED: specks of brown or black pigment – this may be the case in any type of BCC
What are the investigations for BCC? (x1 (x5))
Diagnosis mainly done on clinical suspicion. BIOPSY: punch biopsy, or shave biopsy in cosmetic areas and histopathology – aggregates of cells of varying shapes/sizes, composed of basophilic (meaning stained blue) hyperchromatic (darker nucleus) cells, high nuclear:cytoplasm ratio, palisading (on the edges of the neoplastic nests, nuclei of malignant cells are arranged in a manner similar to a fence), surrounding stroma is hypercellular and fibrous.
What is squamous cell carcinoma?
From the squamous keratinocytes of the epidermis.
What is the aetiology of SCC (squamous cell carcinoma)? (x8)
UV exposure, actinic keratoses (sun-induced precancerous lesion to SCC), ionising radiation, carcinogens (tar, cigarette smoke, soot, arsenic), chronic skin disease (lupus, leukoplakia), HPV, immunosuppression and DNA repair genetic defects (xeroderma pigmentosum).
What are the different types of SCC? (x4)
- Bowen’s Disease: squamous-cell carcinoma IN SITU of the skin – not invaded the basement membrane.
- Verrucous carcinoma: exophytic (solid), fungating (resembling fungus; ulcerations and necrosis), verrucous (thick, heavily keratinized), slow-growing and rarely metastasises
- Marjolin’s ulcer: SCC arising from an area of chronically inflamed/scarred skin.
- Keratoacanthoma: type of SCC which grows rapidly and ‘erupts’, then involutes and disappears.
What is the epidemiology of SCC: Gender? Ethnicity? Age?
More common in men. More common in white ethnicities. More common in over 40s.
What are the signs and symptoms of Bowen’s Disease?
Solitary or multiple red-brown scaly patches.
What are the signs and symptoms of verrucous carcinoma?
Exophytic (solid), fungating (resembling fungus; ulcerations and necrosis), verrucous (thick, heavily keratinized), slow growing
What are the signs and symptoms of keratoascanthoma?
Grows rapidly and ‘erupts’, then involutes and disappears.
What does a well-differentiated SCC look like?
A lump on the skin has a ‘horn’ of keratin growing out of the lump. This is because keratinocytes produce their own keratin. Poorly differentiated SCCs will not have an associated keratin ‘horn’.
What are the different histopathological types of malignant melanoma? (x6)
- SUPERFICIAL SPREADING MALIGNANT MELANOMA – lateral proliferation of malignant melanocytes followed by vertical growth phase and basement membrane invasion.
- NODULAR MALIGNANT MELANOMA – aggressive with no lateral growth phase; vertical proliferation of malignant melanocytes.
- LENTIGO MALIGNA – slow and non-aggressive proliferation of melanocytes within the epidermis and eventually invading local tissue
- ACRAL LENTIGINOUS MELANOMA – melanoma that appears on the palms of hands, feet or subungual (under toenail)
- NODULAR MELANOMA ARISING WITHIN A SUPERFICIAL SPREADING MELANOMA – downward proliferation of malignant melanocytes, following previous horizontal growth.
- AMELANOTIC MELANOMA – where melanoma is non-pigmented
What are the signs and symptoms of superficial spreading malignant melanoma? Where?
They look very dark, asymmetrical, have irregular borders and may change colour, typically arising from a pre-existing naevus. Found commonly on men’s torso and women’s legs.
What are the signs and symptoms of nodular malignant melanoma? Where?
They look very dark and characterised by a lump. Can be found anywhere.
What are the signs and symptoms of lentigo maligna melanoma? Where?
They are large flat, light and dark brown patches, with irregular edges. Usually on face and neck.
What are the signs and symptoms of acral lentiginous melanoma?
Irregular growth or patch on palms of hands or feet, or subungual (shown in photo; persistent melanonychia striata). In subungual, patient may also have Hutchinson’s sign which shows extension of pigment into the proximal or lateral nail fold.
How does Breslow’s thickness correspond to melanoma prognosis?
See photo.
