The Skin (Martin) Flashcards
List the disorders of pigmentation and melanocytes we discussed
- Freckles
- Lentigo
- Melanocytic Nevi
- Dysplastic Nevi
- Melanoma
What differentiates a freckle from a lentingo
Freckles
- Appear after sun exposure
- Fade and darken seasonally
- The amount of pigment being produced by melanocytes changes
Lentigo
- Do not darken after sun exposure
- Number of melanocytes increases (hyperplasia)
What are Cafe au lai spots
Similar histology to freckles but are larger
Seen in neurofibromatosis
Arise idependently of sun exsposure
What is the pathogenesis of Melanocytic Nevi
Mutations in RAS or BRAF (pro-growth) that are limited by the accumulation of p16/INK4a which inhibit CDK4 & CDK6
What is the pathogenesis of Dysplastic Nevi
Activating mutations in NRAS & BRAF genes
Characterictics of Dysplastic Nevus Syndrome
> 50% chance of developing melanoma by age 60
What is the pathogenesis of Dysplastic Nevus Syndrome
CDKN2A or CDK4 gene mutations
Cyclin Dependant Kinase Inhibitor 2A (CDKN2A) - Encodes tumor suppresor genes (p16)
Cyclin Dependent Kinase 4 (CDK4) - modulate cell division and transcription
What is the most deadly of all skin cancers and how is it acquired
Melanoma
Acquired mutations caused by exposure to UV radiation in sunlight (DNA damage)
What are the ABCDEs of melanoma
Asymmetry
Irregular Borders
Variegated Color
Increasing Diameter
Evolution/change over time (esp rapid)
Any pigmented lesion with diameter >6mm, any change, itching or pain
What is the pathogenesis of Melanoma
- Disrupt cell cycle control genes
* CDKN2A mutation (encodes 3 tumor suppressor genes: p15, p16, ARF) - Activate pro-growth signlaing pathways
- Increase RAS & P13K/AKT signaling
- Mutations in BRAF
- Activate telomerase
* Mutations in TERT (most commonly mutated gene)
What are the benign epithelial tumors discussed in lecture
- Seborrheic Keratosis
- Acanthosis Nigricans
- Fibroepithelial polyp
- Epithelial or Follicular Inclusion Cyst (Wen)
Activating mutations in fibroblast growth factor-3 (FGFR-3) is associated with what skin disorders?
Seborrheic Keratoses
Acanthoses Nigricans
What is a Leser-Trelat sign
Paraneoplastic syndrome with a sudden appearance of large numbers of Seborrheic Keratoses indicating carcinomas of the GI tract
What paraneoplastic process is associated with Acanthosis Nigricans
GI adenocarcinomas
What appendage (adnexal) tumors were discussed in class?
- Trichilemmomas
- Cylindroma
- Sebaceous Adenoma
What is Cowden Syndrome
Paraneoplasm of trichilemmoma that warn of internal malignancies such as endometrial cancer and breast cancer
What causes Cowden syndrome
Loss of function in PTEN (a tumor suppressor gene)
What gene is associated with Cylindroma turban tumor
CYLD (tumor suppressor gene)
What syndrome is CYLD associated with
Brooke-Spiegler syndrome
What syndromes are sebaceous adenoma associated with
Muir-Torre syndrome (internal malignancies)
Lynch Syndrome
What were the premalignant and malignant epidermal tumors we discussed in class?
- Actinic Keratosis
- Squamous Cell Carcinoma
- Basal Cell Carcinoma
What can actinic keratosis develop into if given enough time
Squamous Cell Carcinoma
What skin condition is characterized by:
Rough sandpaper-like consistency
Cutaneous Horn (excessive kertain production)
Dyskeratosis (pink cytoplasm)
Parakeratosis (Nuceli seen in stratum corneum)
Actinic Keratosis
What is the second most common tumor arising in sun exposed sites in older people
Squamous Cell Carcinoma
What is the pathogenesis of SCC
- TP53 mutation, mutation in RAS signaling & decreased Notch signaling
- Immunosupression –> Organ transplant, oncogene virus HPV 5 & 8
- Epidermodysplasia verruciformis (Tree ppl) –> HPV
- Industrial carcinogens, chronic ulcers, tobacco and betel nut chewing
- Xeroderma pigmentosum
What do invasive SCC appear as
Nodular, keratin producing lesions that may ulcerate
Dysekeratosis (pink cytopasm) on histology
What is the most common invasive skin cancer
Basal cell carcinoma (BCC)
What is the pathogenesis of BCC
Mutation in Hedgehog signaling & PTCH gene
What is Nevoid basal cell carcinoma Syndrome
Aka Gorlin/Basal cell nevus
Patients present with mutiple BCC before 20 years old
How does BCC present
Pearly papules
Telangiectasias
Rodent ulcers w/ pits in center.
Cells displays peipheral palisading