Dermatopathology Flashcards
Freckle (Ephelis)?
- Most common pigmented lesion of childhood
- 1mm to several tan to reddish brown after sun exposure
- Fades and darkens cyclically with seasonal changes
What are Cafe au lait spots and when are they seen?
- Similar histology to freckles but larger and arise indpenendently of sun
- Seen in neurofibromatosis
- Contain aggregated melanosomes in cytoplasm of melanocytes
What is Lentigo, what does it look like, and its histo?
- Benign localized hyperplasia of melanocytes
- Initiated in infancy and chilhood and occurs at all ages
- 5-10 mm oval tannish brown macules or patches found on mucous membranes and skin
- Do NOT darken with sun
- Histo: Linear melanocytic hyperplasia, restricted to cell layer above the BM
What is a melanocytic nevus? What is the mutation? What does it look like?
- Mole, benign growth acquired by mutations in RAS or BRAF signaling paths
- <6mm tannish brown uniformly pigmented flat macule or elevated papule with well defined roun borders
Histology of a melanocytic nevus?
- Superficial nests : Large round cells with increased melanin
- Deeper: cords or single cells, smaller cells with decreased pigment
- Deepest: fusiform fasicles resembling neural tissue
- Helpful in differentiating benign nevi from melanoma
Junctional nevi?
Nests at dermoepidermal junction
Compound nevi?
- nests or cords grow into underlying dermis and nests in epidermis and dermis
Intradermal nevi?
- no epidermal nests usually older lesions
What is a dysplastic nevi? What mutations?
- multiple can increase risk of melanoma
- not all dysplastic nevi lead to melanoma and not all melanoma comes from dysplastic nevi
- NRAS & BRAF
What does the histology of dysplastic nevi look like?
- larger than acquired nevi >5 mm can be hunreds
- Variegated pigmentation irregular borders of lesions
- Enlarged epidermal nests that may coalesce with other nests
What is lentiginous hyperplasia?
- single nevus cells replacec basal cells along E-D junction
- Histology seen in dysplastic nevi
What is Atypia?
- Ig nuclei with irregular angulated nuclear contour hyperchromasia
Melanoma location?
- Skin
- Oropharynx
- GIGI tracts
- Esophagus
- Meninges
- Uvea of eye
If melanoma is inherited what is the pattern?
- AD 10-15% of people
- majority sporadic though
Melanoma risk factors?
- light complexion hair eyes
- history of blistering subnurns
- proximity to equator
- Indoor occupation outdoor hobbies
- Family hx of melanoma or dysplastic nevi
- PJrecurosor lesions
- XP
Where will melanoma show up more likely on african americans and asians?
- Soles
- Mucous membranes
- Palms
- Nail beds
Driver mutations in melanoma? What does it encode?
- CDKN2A in 40% AD familial melanomas and 10% in sporadic
- p15. p16 ARF
- Increased RAS and P13K/AKT signaling activation of pro growth signaling
- BRAF in 40-50% melanomas
- Activate telomerase TERT in 70% tumors
What is radial growth?
- Horizontal spread of melanoma within the epidermis and superficial dermis, cells lack the ability to metastasize
- lentigo maligna: indolent lesion on face of older men can stay in growth phase for several decades
- Superficial spreading is the most common and related to sun exposure
- Acral/mucosal lentiginous: melanoma un related to sun exposure
What is vertical growth?
- tumor cells invade down into dermal layers as expansible mass after an unpredictable amount of time in radial phase
- appearance of nodule and correlates with emergence of tumor subclone with metastatic potential
- Probability of metastasis in a lesion correlates with depth of invasion
Favorable prognosis with melanoma?
- thinner tumor depth
- NO mitosis
- Brisk tumor infiltrating lymphocyte response
- NO regression
- Lack of ulceration
What are the types of benign epithelial tumors?
- Seborrheic keratoses
- Acanthosis nigricans
- Fibroepithelial polyp
- Epithelial or follicular inclusion cyst (Wen)
What is Seborrheic Keratoses? Mutation?
- Middle age or older individuals arises spontaneously in the trunk primarily, extremities, head and neck
- Round flat coin like waxy papules that are tan dark brown, velvet or granular surface
- pore like ostia impacted with keratin
- horn cysts
- Mutation is FGFR-3
Dermatosis papulosa nigra?
- people of color get multiple small lesions on their face
- (seborrheic keratosis)
What is Leser-Trelat sign?
- Paraneoplastic syndrome, sudden appearance of large numbers of Seb Ks
- assoc with carcinomas of GI tract
Acanthosis nigrican?
- cutaneous sign of several underlying benign and malignant conditions
- Thickened hyperpigmented skin with velvet like texture in flexural areas or intertriginous areas
- 80% assoc. with obesity and diabetes
- Remaining cases with cancer such as GI adenocarcinomas
- familial form FGFR3
- DM2 mutation in IGFR1
Acanthosis nigricans histology?
- Epidermis and underlying elnarged dermal papillae undulate sharply into numerous peaks and valleys
- Variable hyperplasia with hyperkeratosis and slight basal cell layer hyperpigmentation
- no melanocytic hyperplasia
What is a Fibroepithelial polyp? Histology? Tx?
- aka Acrochordon, squamous papilloma, skin tag
- assoc diabetes, obesity and intestinal polyposis
- Soft flesh colored bag like tumors attached by slender stalk
- Fibrovascular cores covered by squamous epithelium
- Torsion leading to ischemic necrosis to removal
What is epithelial or follicular inclusion cyst (Wen)?
- Invagination and cystic expansion of epidermis or hair follicle
- Subject to traumatic rupture spilling keratin into dermis
- extensive and painful granulomatous inflammatory responses
Adnexal tumors?
- hundreds of neoplasms arising from or showing differentiation toward cutaneous appendages
- Nondescript flesh colorerd solitary or multiple papules and nodules
What is Cowden syndrome?
- Multiple trichilemmomas
- loss of function in PTEN
- Increase risk for endometrial cancer and breast cancer
- (adnexal tumor)
What is Cylindroma?
- Ductal differentiation on forehead or scalp
- “Jigsaw puzzle”
- Turban tumor : CYLD
- CYLD assoc genetic syndroms like familial trichoepithelioma and brooke spiegler
Eccrine poroma?
palms and soles where there are increased sweat glands
Syringoma?
- Eccrine differentiation small tan papules lower eyelids
- (adnexal tumors)
Sebaceous adenoma?
- Muir Torre syndrome
- Hereditary nonpolyposis colorectgal carcinoma (Lynch Syn.)
- DNA mismatch repair proteins
- Adnexal tumor
Pilomatricoma?
- follicular differentiation
- CTNNB1 encoding B-catenin
- Hair growth and maintenance
- Adnexal tumor
Premalignant and Malignant epidermal tumors?
- Actinic Keratosis
- SCC
- BCC
Actinic Keratosis?
- Sun damaged skin hyperkeratosis on the face arms and dorsum of hands
- Lightly pigmented people, ionizing radiation exposure, industrial hydrocarbons, arsenic
- Progressively worsens to SCC if given enough time
- <1 cm tan to brown red or skin colored, sandpaper consistency
- Cutaneous horn due to excessive keratin production
- Dyskeratosis with intracellular bridges, blue gray elastosis, parakeratosis
- Actinic Chelitis: similar lesions on lips
What are the first and second most common tumor arising in sun exposed areas?
- BCC
- SCC
Epidermodysplasia verruciformis? What does it have increased risk for?
- HPV is implicated in cause
- Increased risk for cutaneous SCC
SCC mutation?
- Acquired defects in precursor AK, TP53 mutations
- p53 dysfunction is an early event
- Mutations in RAS and decreasing notch signaling
What is XP?
- XPA gene mutation in NER pathway with decrease repair of pyrimidine dimers and increased SCC risk