Fung II Flashcards
T/F: Benign or malignant neoplasms can only arise in the epidermis
False; they can arise from any component of the skin, including epidermis (squamous or melanocytic), dermis, or adnexal
What is this:
neoplasm of unknown origin; no malignant potential; round flat coin-like lesion that is waxy
sebhorreic keratosis
What are some microscopic observations for skin tags?
loose stroma surrounded by epidermis; papillomatosis
Deposition of collagen in the formation of a scar; common in African Americans
keloids (hypertrophic scars)
What will you see microscopically with keloids?
keloidal collagen
This benign epithelial tumor will invaginate into the dermis and can rupture and allow keratin to spill out into the surrounding area
epidermal inclusion cyst
This premalignant tumor is due to sun damage; causes hyperkeratosis of skin leading to tan/brown skin lesions that feel like sand paper
actinic keratosis
Does actinic keratosis extend to the whole epidermis?
no
What is a characteristic microscopic feature of actinic keratosis?
atypical keratinocytes with abnormal nuclei (large and dark)
What is a characteristic microscopic feature of squamous cell carcinoma in situ?
full thickness atypical cells in epidermis
What are two features of squamous cell carcinoma that we should keep in mind?
intracellular bridges atypical keratinocytes (dark, large nuclei)
How does basal cell carcinoma typically present?
pearly, pigmented papules; locally aggressive tumor often occurring on the face
**can erode into the bone if not taken care of
What are three characteristic features of a basal cell carcinoma?
peripheral palisading
stromal retraction
horn cysts
**can be pigmented
In what condition is solar elastosis seen?
melanocyte neoplasms
What is the spectrum of melanocytic neoplasms from benign to malignant?
nevus
dysplastic nevus
melanoma
Common benign neoplasms that are acquired by activating mutations in the Ras signaling pathway
nevus
Nevus(es) are considered neoplasms. Why?
because they are acquired by a mutation in the Ras signaling pathway
What are the three morphological phases that a nevus can progress through, and how are they different?
junctional nevus: flat, nevoid cells only in epidermis
compound nevus: more mature, raised, nevoid cells in dermis and epidermis
intradermal nevus: only in dermis
What is a difference between a nevus and a melanoma?
melanomas do not progress through morphologic phases; also, melanomas do not have the P16 checkpoint (which keeps nevuses from proliferating too much)
May be direct precursors of melanoma
Vast majority are stable and never progress
Have acquired activating mutations in NRAS and BRAF genes
dysplastic nevus
What genes acquire mutations in a dysplastic nevus?
NRAS
BRAF
Most deadly of all skin cancers, but can be cured if detected in its early stages
Mostly occurs on the skin but can occur within the mucosa
melanoma
Melanomas can be genetic (10-15%) or sporadic (due to UV radiation. How can UV radiation cause melanoma?
disrupts cell cycle control genes
activates pro-growth signaling pathways
activates telomerase
What are the two growth phases in melanoma?
radial - grows just in the epidermis
vertical - grows through the basement membrane of the epidermis to the dermis
If you see hyperplasia of the sebaceous glands, what type of neoplasm is this considered?
adnexal
What is a pilar cyst?
a cyst of hair follicles with compact keratin inside the cyst
What is pilomatricoma?
a pilar cyst with calcifying of the lesion
**look for shadow cells
When would you see a pigmented basal layer, spindle cells, and keloidal collagen?
dermatofibroma
**DFSP penetrates further into the dermis
