Nonmelanoma Skin Cancer Flashcards
What are the types of UV light that can damage the skin?
UVA (320-400 nm) - mostly reaches earth, even through clouds and windows, penetrates deep within the skin and causes tanning and photoaging
UVB (290-320 nm) - absorbed within the epidermis, causing burning and delayed tanning
UVC (200-290 nm) - shielded by ozone
What are common clinical signs of photoaging?
spotty hyperpigmentation and hypopigmentation
rhytids (wrinkles)
telangiectasias
skin thickening
loss of elasticity
What is the multiple step model of photocarcinogenesis?
UV mediated DNA damage - direct (thymidine dimer) and indirect (ROS) damage
mutation formation - tumor suppressor genes, oncogenes, apoptosis evation, telomerase
genetic syndromes with mutations in oncogenes or tumor suppressors result in predisposition to skin cancer
What are the benefits of UV?
converts vitamin D (1,25(OH)2VitD3) to the metabolically active form
What are the major types of skin cancer?
nonmelanoma skin cancer (NMSC) - basal cell sarcinoma BCC (>1 million cases per year) and squamous cell carcinoma SCC (>200,000 per year)
melanoma - >75,000 melanomas per year and ~9,000 deaths per year
What are some risk factors for NMSC?
environmental exposure - UV, ionizing, chemical radiation, smoking
skin type - fair skin or blond/red hair
genetic predisposition - xeroderma pigmentosum, albinism, basal cell nevus syndrome
predisposing skin conditions - chronic ulcers, longstanding inflammatory conditions, burns
immunosuppression - solid organ transplant recipients
Fitzpatrick Skin Phototypes
used to classify skin based on the ability to burn and tan when challenged with UV radiation
photoprotection is recommended for all skin types, including the darkest of skin
type I is the most likely to burn, while type VI is the least likely
What are the diagnostic features of BCC?
started as a pimple and gets bigger
pearly papule with telangiectasias that easily bleeds or crusts
What are the diagnostic features of SCC?
rough red papule or plaque that continually enlarges
can bleed or ulcerate
may appear and grow rapidly
Describe the common skin biopsy techniques.
punch biopsy vs. shave biopsy
What are the common histological characteristics of BCC?
rounded nests of “basaloid” cells
peripheral palisading
fibromyxoid stroma
cleft formation
What is the management of BCC?
surgical excision with margins
photoprotection
regular total body skin examinations
monthly self-skins exams
What is the etiology of basal cell carcinoma (BCC)?
neoplasm arises from nonkeratinizing keratinocytes that originate in the basal layer of the epidermis
the etiology includes UV radiation that induces DNA damage
PITCH (tumor suppressor gene) mutation - spontaneous/acquired mutations from UV-induced DNA damage
What are the risk factors for BCC?
sking types I and II
history of intermittent or intense or prolonged UV exposure
history of ionizing radiation exposure or arsenic ingestion
immune suppression (transplant patients, systemic immunosuppressive medications)
genetic conditions that increase skin cancer risk
nodular BCC
most common subtype
pearly papule or nodule with rolled border and telangiectasias
although any part of the body may be involved, the lesions ar emost frequently found on the head and neck
superficial BCC
pink or translucent color, telangiectasia, and a slightly rolled border
patch or a thin plaque, which may be scaly
differential diagnosis may include squamous cell carcinoma in situ or actinic keratosis
ulcerated BCC
translucent color, telangiectasia, and a rolled border
ulceration and crusting (scab)
pigmented BCC
pearly papules with telangiectasias and globules of dark pigment within
differential diagnosis may include malignant melanoma
morpheaform BCC
translucent color, telangiectasia, and a rolled border
plaque appears white and bound down or scarl-like in areas
What are the histological findings of squamous cell carcinoma?
normal epidermis
dermal extension of well-differentiated (“keratinizing”) keratinocytes
What are some clinical manifestations of SCC?
papule, plaque, or nodule
pink, red, or skin-colored
scale
exophytic (grows outward)
indurated (dermal thickening, lesion feels thick and firm)
may present as a cutaneous horn
friable - bleed with minimal trauma
asymptomatic - painful or puritic
SCC in situ
Bowen’s disease
circumscribed pink-to-red patch or thin plaque with scay or rough surface
keratinocyte atypia is confined to the epidermis and does NOT invade past the dermal-epidermal junction
xeroderma pigmentosum
rare, autosomal recessive disease
genetic defect in nucleotide excision repair (NER) genes
defect prevents removal and repair of photoproducts from damaged DNA and multiple genes are involved
developed hundreds of skin cancers at an early age (1000x risk of skin cancer, including melanoma)
only management is complete sun avoidance
Nevoid Basal Cell Carcinoma Syndrome (Gorlin Syndrome)
rare autosomal dominant disease
gene defect in tumor suppressor gene PTCH (Patched)
leads to constitutive activation of sonic hedgehog because it can no longer inhibit SMO (smoothened protein) and predisposes to BCCs
oculocutaneous albinism
group of genetic disorders with partial or complete absence of melanin - normal number of melanocytes
increased frequency of SCC and melanoma
only prevention is strict sun-avoidance
