Skin Cancer B&B

Question 1

what are the 3 types of skin cancers and the cell types which drive them?

Answer 1

1. basal cell (most common) = stem cells (stratum basal)
2. squamous cell = keratinocytes
3. melanoma = melanocytes (epidermis-dermis junction)

Question 2

actinic keratosis

Answer 2

aka solar keratosis: premalignant skin lesions caused by sun exposure

growth of atypical epidermal keratinocytes - round, red/brown papules or plaques

can lead to squamous cell carcinoma

Question 3

premalignant skin lesions caused by sun exposure

Answer 3

actinic keratosis, aka solar keratosis: growth of atypical epidermal keratinocytes - can lead to squamous cell carcinoma

round, red/brown papules or plaques in sun exposed areas

Question 4

what does biopsy of actinic keratosis show?

Answer 4

premalignant skin lesions caused by sun exposure, growth of atypical epidermal keratinocytes - can lead to squamous cell carcinoma

round, red/brown papules or plaques in sun exposed areas

biopsy: perakaratosis (retained nuclei in stratum corneum), hyperkeratosis, epidermal cell dysplasia

Question 5

how do squamous cell carcinoma lesions appear, and what is the hallmark pathological finding?

Answer 5

red, scaling plaques with sharp borders; advanced lesions may ulcerate/crust/bleed

pathology shows keratin pearls (look like roses or onions)

Question 6

in which patients is squamous cell carcinoma most common? what are the risk factors (4)?

Answer 6

2nd most common skin cancer, occurs in older patients (>75)

risk factors: sun exposure, chronic immunosuppression, chronic skin inflammation, arsenic exposure

note <5% metastasize

Question 7

Pt is A 76yo M presenting with red, scaling plaque with well-demarcated borders on their ear. PMH includes a kidney transplant 10 years ago. what do you suspect the biopsy will show? What is the prognosis?

Answer 7

most likely squamous cell carcinoma - pathology shows keratin pearls (look like roses or onions)

2nd most common skin cancer, occurs in older patients (>75)

risk factors: sun exposure, chronic immunosuppression, chronic skin inflammation, arsenic exposure

note <5% metastasize

Question 8

arsenic exposure is a risk factor for which type of skin cancer?

Answer 8

squamous cell carcinoma

arsenic may be found in contaminated drinking water

Question 9

how do keratoacanthomas appear? describe the disease progression - how are they treated?

Answer 9

variant of squamous cell carcinoma, usually benign and self-limited

dome-shaped nodule with central hyperkeratosis (black spot)

grow rapidly (weeks), but then regress - removed surgically or followed for regression

Question 10

Pt presents to dermatologist with a dome-shaped nodule with central hyperkeratosis, which they state has grown rapidly in size over the past 2 weeks. Diagnosis? How will you treat it?

Answer 10

keratoacanthoma: variant of squamous cell carcinoma, usually benign and self-limited

grow rapidly (weeks), but then regress - removed surgically or followed for regression

Question 11

how does Bowen’s Disease appear?

Answer 11

squamous cell carcinoma in situ - hasn’t broken through basement membrane and invaded dermis

well-demarcated, scaly patch or plaque

Question 12

what is the most common form of skin cancer, and how does it progress?

Answer 12

basal call carcinoma: slow growing, rarely metastasize

lowest potential for recurrence or metastases of skin cancers (basal < squamous < melanoma)

most found early and excised

Question 13

which type of skin cancer is LEAST likely to recur or metastasize?

Answer 13

basal cell carcinoma: also most common

has lowest potential for recurrence/metastases (basal < squamous < melanoma)

Question 14

how do basal cell carcinoma lesions appear?

Answer 14

pearly/shiny papules or nodules, may have telangiectasia on surface (dilated blood vessels)

may ulcerate with crust in center, borders may be “rolled” (rounded, thickened)

most common type of skin cancer, least likely to metastasize or recur

Question 15

what will histology of a basal cell carcinoma lesion show? (2)

Answer 15

nests of dark “basaloid” cells in the dermis + palisading nuclei (cells at periphery of nests line up in parallel)

(big round patches like chocolate chips in a cookie)

Question 16

Pt presents to dermatologist with concern of a skin lesion on their nose. The lesion appears pearly and there are telangiectasia on the surface. A biopsy is taken which shows nests of dark cells with palisading nuclei at the peripheries. What is the most likely diagnosis, and what is the prognosis?

Answer 16

basal call carcinoma: slow growing, rarely metastasize

lowest potential for recurrence or metastases of skin cancers (basal < squamous < melanoma)

Question 17

how does superficial basal cell carcinoma appear? (variant of BCC) where does it most likely occur?

Answer 17

light red to pink plaques with slight scaling

most commonly occur on the trunk

can be easily mistaken for psoriasis or other skin disorders

Question 18

how can melanoma be recognized?

Answer 18

ABCDE:
Asymmetrical
Borders are irregular
Color variation
Diameter >6mm
Evolving over time

[most malignant form of skin cancer, and highly malignant at that!]

Question 19

what are the 2 main subtypes of melanoma?

Answer 19

1. superficial spreading: most common, spreads laterally on the surface (initially)
2. nodular: aggressive subtype, grows vertically to form nodules (into dermis)

Question 20

lentigo maligna

Answer 20

lentigo = small, dark, flat spot (large freckle), confined to epidermis

lentigo maligna = growing dark spot confined to epidermis (“melanoma in situ”)

lentigo maligna melanoma = invasion of dermis, but slow growing - take years to develop (occur in elderly)

Question 21

which patients most commonly present with acral lentiginous? where does it occur?

Answer 21

least common type of melanoma (<5%) EXCEPT it is most common type in dark-skinned patients (African, Asian)

occurs on extremities - palms, bottom of foot, under nails

Question 22

most common type of melanoma in dark-skinned patients occurring on palms, bottoms of feet, under nails

Answer 22

acral lentiginous - note, least common type of melanoma overall (<5%)

Question 23

what is the tumor marker of melanoma?

Answer 23

S100: calcium binding protein in nucleus

highly specific (however low sensitivity - many melanomas lack this marker)

Question 24

biopsy of lesion is positive for S100 - based on that alone, what is it most likely?

Answer 24

melanoma

S100: calcium binding protein in nucleus

highly specific (however low sensitivity - many melanomas lack this marker)

Question 25

what is the clinical use of the Breslow thickness?

Answer 25

Breslow thickness = distance from granular epidermis to deepest tumor cells

used to measure depth of melanoma tumor to estimate risk of metastasis

melanoma initially spreads laterally along epidermis, then shifts to vertical growth phase downward in dermis

Question 26

how does melanoma metastasize (2)? where does it most often metastasize (3)?

Answer 26

metastasis via hematogenous and/or lymphatic spread

spreads to lungs, liver, brain - most common cause of death is metastasis

Question 27

what is the most common genetic mutation in sporadic melanomas? include the most common specific mutation

Answer 27

BRAF gene mutations (40-50% of sporadic melanomas) due to V600E mutation (90%)

BRAF = proto-oncogene, triggers cell proliferation via RAS pathway

tx is BRAF inhibitors: vemurafenib or dabrafenib

Question 28

which 2 BRAF inhibitors can be used to treat sporadic melanomas with a BRAF gene mutation?

Answer 28

1. vemurafenib
2. dabrafenib

BRAF gene mutations (40-50% of sporadic melanomas) due to V600E mutation (90%)

BRAF = proto-oncogene, triggers cell proliferation via RAS pathway

Question 29

what is the effect of the BRAF proto-oncogene? what pathway is it part of?

Answer 29

growth factor —> tyrosine kinase receptor —> RAS

RAS can activate 1. PI-3K (cell survival) or 2. BRAF (cell proliferation)

Question 30

fill in the blanks regarding the RAS pathway:
1. growth factor binds ______ receptor
2. receptor activates RAS
3. RAS can activate _____ or ______, respectively leading to ____ or _____

Answer 30

growth factor —> tyrosine kinase receptor —> RAS

RAS can activate 1. PI-3K (cell survival) or 2. BRAF (cell proliferation)