What are the 9 risk factors for non-melanoma skin cancers?
What wavelengths are UVA, B and C?
Which is most damaging?
UVA = 400 -320nm
UVB = 320 -290nm
UVC =290 -200 nm
Shorter wavelength = more energy and the more detrimental to the skin
So from worst to best: UVC, UVB, UVA
What have clinical/epidemiological studies and experimental studies shown about the effects of UV on skin cancer?
Clinical/epidemiological:
UVB is implicated as a non-melanoma carcinogen esp. in fair-skinned individuals living in areas of intense sun exposure. The cancers are distributed on sun-exposed skin of head, neck, upper extremities and torso
Experimental:
Animal studies show UVB to be a carcinogen for non-melanoma
What is the most common type of skin cancer in patients with dark skin?
SCC
Cumulative UVB over time is critical for causing _______________ skin cancer. Acute sunburn episodes early in life, on the other hand, promote the development of ______________.
Cumulative UVB = non-melanoma skin cancer
Acute burns = melanoma
The increased incidence of skin cancer in fair-skinned people who tend to burn and have difficulty tanning implicates what?
There is a genetic role in estimating the risk of skin cancer
What 2 genetic disorders make people exquisitely sensitive to sun-induced disorders and the development of skin cancer at an early age?
2. xeroderma pigmentosum- defective repair of UV-induced DNA damage
In what genetic disorder do patients have a predisposition towards infections by HPV, and get skin cancers early and in increased number on sun exposed areas?
Epidermodysplasia verruciformis - the synergy between virus and sunlight cause skin cancer
What are the 7 main risk factors for melanoma?
What “precursor lesions” put a person at risk for melanoma?
What percent of melanomas develop from them?
1/3 of melanomas develop from a precursor
What FHx predisposes to melanoma?
What is the most common skin cancer?
What race is most likely to get it?
What gender?
What age group?
Basal cell carcinoma
white, men
40-79 yrs old
What is the pathophys of basal cell carcinoma?
From what cell does it arise?
How does it grow?
A 50 year old man presents with dome-shaped, pearly/flesh-colored papule with telangiectasia. The center looks slightly ulcerated.
You do histology and see:
- aggregates of BASALOID CELLS contiguous with the epidermis
- cells are uniform size, with large nuclei, scant cytoplasm
-cells in the periphery of tumor are PALISADING
-CLEFTS between the stroma and the neoplastic cells
What is the likely diagnosis?
basal cell carcinoma - nodular type
A 63 year old woman presents with erythematous scaly patch with irregular borders. You think it is eczema, but are not 100% sure, so you take a biopsy.
Histology shows:
What is the diagnosis?
BCC - superficial type
A patient presents with white plaque/papule scar-like lesion.
Histology shows:
- cords strands and nests of basaloid cells in a dense stroma of thickened collagen bundles
- no connection to the epidermis
What is the diagnosis?
What must you do to decrease chance of recurrence?
BCC- sclerotic/morpheaform type
**much more aggressive than other types of BCC and requires Mohs surgery to decrease change of recurrence
A patient presents with a dark-colored tumor on her face. She says it has been growing slowly and expanding to local skin.
On histology, you see:
- aggregates of basaloid cells, sometimes contiguous with the epidermis
- clefts separating the basaloid cells from the stroma
- cells in there periphery palisading
- abundant melanin
What is the likely diagnosis?
BCC- pigmented type
What race is most affected by squamous cell carcinoma?
What age group?
What gender?
White, 40-79, men
*SCC is the most common skin cancer in African American and Asian patients
What is the pathophysiology of SCC? What cell does it arise from? How does it grow? What induces most cases on the skin? What about if it is a nailbed or genital lesion?
It arises from suprabasal keratinocytes in the epidermis and grows by direct extension into the dermis/subcutis.
Most cases are UV induced and occur in patients with chronic sun exposure.
Nailbed or genital lesion suggests HPV infection
What are the 2 precursors for SCC?
A patient presents with a hyperkeratotic plaque on a sun-exposed area. The lesion can be readily peeled but tends to recur.
Histology shows:
1. focal areas of atypical keratinocyte proliferation
2. overlying parakeratosis [nucleated]
3. spared adnexal areas
What is the likely diagnosis?
What is this a precursor lesion for?
Actinic Keratosis- precursor lesion for SCC
What are the 3 types of SCC in situ?
Describe the:
Of Bowen’s disease.
An uncircumscribed man presents with a bright, erythematous plaque that is smooth and velvety on the glans penis. What is the diagnosis?
What is this a precursor for ?
Erythroplasia of Queyrat
- SCC in situ