Common Skin Cancers

Question 1

Basal cell cancer

Answer 1

Begins in the staratum basale from pluripotent stem cells due to mutations in the hedgehog -> most commonly mutations inactivate PTCH1 (a tumor suppressor gene)

Other mutations may activate Smoothened or Hedgehog

Usually begin in areas exposed to the sun. Grows very slowly and don’t normally metastasize. Can reoccur (35-50% within 5 years)

Question 2

Actinic Keratosis

Answer 2

Also called intraepidermal neoplasia I -> most common pre-malignant skin legion

Can eventually develop into invasive squamous cell carcinoma

Occur in fair skinned individuals - typically produced by UV radiation. Sunscreen reduced likelihood of getting them.

Question 3

Treatment options for AK

Answer 3

Cryotherapy
5-flourouracil (anti-neoplastic effect via thymidine synthase)
Imiquimod -> TLR7 agonist
Diclogenac -NSAID, inhibits COX2 -> reduction of prostaglandins
Photodynamic therapy - topical t-aminovulinic acid accumulates in dysplastic cells -> upon exposure to radiation, cell death
Ingenol mebutate - active agent in the sap of Australian plant. How? Idk

Question 4

Squamous cell carcinoma

Answer 4

Appears as growing lumps, often w/ rough surface or as flat, reddish patches that grow slowly.

Begins in the upper portion of the epidermis. Second most common cutaneous malignancy. Sun exposed skin -> can sometimes begin w/ scars or other injured areas (Marjolin’s ulcer)

More likely to invade fatty tissues beneath the skin.

Question 5

Squamous cell carcinoma in situ (Bowen’s disease)

Answer 5

Subtype of SCC

Earliest form of squamous skin cancer. Looks like scaly, reddish patches that may be crusted. Major risk factor = too much sun.

Question 6

Keratoacanthoma

Answer 6

Subtype of SCC

Appear as solitary lesion in sun exposed skin. Develop quickly (6-8 weeks) w/ sizes of 1-3 cm.

Cup-shaped invagination of the epidermis with keratin filled central crater.

Question 7

Invasive squamous cell carcinoma

Answer 7

Occurs typically as a hyperkeratotic papule w/ variable size and thickness and indistinct margins

Metastasis is more common in lip, external ear, or perineural invasion

Question 8

Non-melanoma skin cancer (NMSC)

Answer 8

Risk factors: UV light - damages DNA in keratinocytes. Fair skin, Gender (men 2x likely) Chemicals, Radiation, having skin cancer, phototherapy, genetic skin diseases (basal cell nevus syndrome, xeroderma pigmentosum) immunosuppression, HPC, smoking

Some treatments that I didnt talk about earlier:

Curettage - looped blade scares tumor away from ajacent normal skin
Excision - cut off w/ margin
Mohs micrographic - less margin, evaluate
Radiotherapy - radiation duh

Question 9

Melanoma

Answer 9

About 3% of skin cancer but large majority of skin cancer deaths

Can arise from previous nevus, but 70% are de novo

ABCD’s. Ugly duckling rule. If neglected, tumor invasion can get deeper.

Nodular melanoma -> does not have a macular or plaque phase and presents as black or blue papule or nodule

Men: upper back, legs on women. Family history, presence of numerous acquired nevi, or history of blistering sunburns.

Question 10

Lentigo maligna melanoma and acral lentiginous melanoma

Answer 10

Not correlated w/ intense intermittent sun exposure

Lentigo maligna -> 5% of all melanomas, seen at sites of max sun exposure.

Acral lentiginous -> 3-8% of all melanomas, arise in the volar skin of the palms or soles and the nailbeds. (most common melanoma in not whites)

Question 11

Breslow depth

Answer 11

MOST IMPORTANT INDICATOR OF PROGNOSIS FOR ALL SUBTYPES OF MELANOMA

Is the maximal thickness of tumor invasion measured by ocular micrometer (recorded in mm w/ less than 1.0 good, thicker than 4mm bad)

Question 12

Clark level

Answer 12

describes how far a melannoma has penetrated into the skin instead of measuring it. Uses scale of I-V

• the cancer stays in the epidermis (Clark level I)
• the cancer has begun to invade the upper dermis (Clark level II)
• the cancer involves most of the upper dermis (Clark level III)
• the cancer has reached the lower dermis (Clark level IV)
• the cancer has invaded to the subcutis (Clark level V)

Question 13

Genetics of melanoma

Answer 13

BRAF mutation found in many melanomas -> not inherited, develops during melanoma

Question 14

Treatment of Melanoma

Answer 14

In situ - wide local excision w/ .5 cm margins

2mm in dept - excised w/ 2 cm margin

Plus greater than 1mm would have sentinel lymph node biopsy

Question 15

Standard therapy for pts w/ stage 4 and recurrent melanoma

Answer 15

1. ) Immunotherapy -> monoclonal antibody (Ipilimumab) that clocks activity of cytotoxic T-lymphocyte antigen 4 -> IL-2 response decent
2. ) Signal transduction inducers Venurafenib, selective BRAF mutation (V600E mut)
3. ) Chemo
4. ) Palliative local therapy

Question 16

Kaposi’s Sarcoma

Answer 16

endothelial malignancy triggered by HHV-8, slowly progressive, really rare

Classic - elderly men of eastern european descent
Lymphadenopathic - aggressive form primarily in equatorial Africa, young men, very fatal
AIDS-associated -> no good

Question 17

Prevention of skin cancer

Answer 17

Limit UV exposure
Protect your skin w/ clothes
Wear a hat!
Use sunscreen 
Wear sunglasses
Seek shade
Protect children
Avoid harmful chems