Ch 23 - Skin tumors Flashcards
Seborrheic keratosis:
- common pigmented epidermal tumor
- middle-aged or older persons
Where are the seborrheic keratosis located?
- trunk (most numerous)
- extremeties
- head
- neck
Seborrheic keratosis appearance:
- round, exophytic, coin-like plaques
- have a “stuck-on” appearance
- monotonous sheets of small cells that resemble the basal cells of the normal epidermis
What occurs on the surface of seborrheic keratosis? aka their characteristic features.
- hyperkeratosis
- presence of small keratin-filled cysts (horn cysts) and downgrowth of keratin into the main tumor mass (pseudo-horn cysts)
What is the color of seborrheic keratosis?
- tan to dark brown
- have velvety- to granular appearing surface
- the dark color suggests melanoma, leading to surgical removal
Actinic keratosis:
- overt malignancy of the epidermis (squamous cell carcinoma in situ)
- dysplastic changes
What is results into actinic keratosis?
- chronic exposure to sunlight
- associated with hyperkeratosis
- TP53 mutations caused by UV light-induced DNA damage
What is the size of actinic keratosis?
less than 1cm in diameter
What is he color of actinic keratosis?
- brown or red in color
Actinic keratosis appearance:
- rough (sand-paper like) to the touch
- infrequently progress to carcinoma in situ
What does the dermis contain in actinic keratosis?
- thickened blue-gray elastic fibers (solar elastosis), the result of chronic sun damage
How is the stratum corneum in actinic keratosis?
thickened with retained nuclei (parakeratosis)
How are the lower portions of epidermis in actinic keratosis?
lower portions of epidermis show CYTOLOGIC ATYPIA (caused by sun exposure), often associated with hyperplasia of basal cells or with atrophy and diffuse thinning of the epidermal surface
In who are actinic keratosis most common?
- fair-skinned people
- increase incidence with age and sun exposure
Actinic keratosis treatment:
- local crytherapy (superficial freezing)
- topical agents
Give examples of benign and premalignant epithelial lesions:
- seborrheic keratosis
- actinic keratosis
Give examples of malignant epithelial tumors:
- squamous cell carcinoma
- basal cell carcinoma
What is a common tumor arising on sun exposed sites in older people?
squamous cell carcinoma
Squamous cell carcinoma frequency:
- more men than women
Squamous cell carcinoma predisposing factors:
- sunlight
- chronic ulcers
- old burn scars
- ingestion of aresenicals
What is the most common exogenous cause of squamous cell carcinoma?
UV light exposure
Other causes, than UV light-induced exposure, that are reasons of squamous cell carcinoma:
- TP53 mutations caused by UV light-induced DNA damage
- activating mutations in HRAS and loss-of-function in Notch receptors, which transmit signals that regulate the orderly differentiation of normal squamous epithelia
How does the UV light (UVB in particular) have transient immunosuppressive effect on skin?
by weakening impairing antigen presentation by Langerhans cells
Basal cell carcinoma
- common slow-growing cancer that rarely metastasize
Where does basal cell carcinoma occur?
- at sites subject to chronic sun exposure
- lightly pigmented individuals
What is ybasal cell carcinoma associated with?
dysregulation of Hedgehog pathway
What can cause familial basal cell carcinoma in Gorlin syndrome?
inherited defects in the PTCH gene, a tumor suppressor that regulates Hedgehog pathway signaling
What can be mutated in sporadic basal cell carcinoma?
some components of hedgehog pathway
What type of mutation can occur in both familial and sporadic basal cell carcinoma?
mutation in TP53
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MORPHOLOGY
