Non-melanoma skin cancer

Question 1

Non-melanoma skin cancer statistics

Answer 1

• Most commonly diagnosed cancer
• 1/2 men and 1/3 women
• If you have 1 NMSC, you have >50% of developing a second NMSC
• UV radiation, often causing p53 mutations, is the major cause of NMSC
• Chronic sun exposure and intermittent intense exposure are risk factors
• ICd patients especially susceptible

Question 2

Actinic Keratosis (AK)

Answer 2

• In situ epidermal dysplasia from chronic sun exposure
• Percursor to SCC
• Often in face, ears, scalp, hands, forearms
• Rough, sandpaper-like surface
• Hyperkerotic pearly gray-white appearance
• Rx: liquid N2, topical 5-FU, Imiquimod (immunotherapy cream), photodynamic therapy (PDT) uses ALA (levulinic acid) and a specific wavelength of light to generate ROS, chemical peel (including burns)

Question 3

Cutaneous Horn

Answer 3

• Skin colored, antler-like projection commonly on scale and face
• Can overlie a squamous or basal cell CA (must have histological examination of base)
• Rx w/ excision or Mohs surgery

Question 4

Keratocanthoma (KA)

Answer 4

• Rapidly-growing dome-shaped crateriform papule/nodule w/ central crater of keratin
• Considered a well-differentiated SCC (often malignant, especially on face)
• Induced by sun exposure, trauma, surgery
• Muir-torre syndrome: sebaceous adenoma and KA in association w/ internal malignancy
• Rx: Excision, Mohs, radiation, chemo

Question 5

Squamous cell carcinoma (SCC)

Answer 5

• 2nd most common type of skin CA
• Develops on sun-exposed sites along AKs, appear as scaly eczematous plaque/papule
• Induced by chronic sun exposure
• Chronic scarring processes are risk factors (ulcers, burns, EB, ect), along w/ HPV, ICd, AKs, XP
• Favors lower lip, more likely to metastasize than BCC (.5-5%)
• More likely to metastasize when >2cm diameter, ICd patients, perineural involvement
• Rx: excision/Mohs, radiation, oral retinoids, capecitabine (converted to 5-FU)

Question 6

Bowen’s disease

Answer 6

• Erythematous, slightly scaly and crusted patch that is ill-defined
• Intra-epidermal SCC (SCC in situ), arises from adnexal epithelium and invades epidermis
• Disorganized epidermis (no maturation)
• Can be more aggressive than SCC
• Rx: Imiquimod, 5-FU, Mohs/excision, CO2 laser, radiation, PDT

Question 7

Basal cell carcinoma (BCC)

Answer 7

• Most common skin cancer, associated w/ mutations in CDKN2A or p53
• Also associated w/ inactivation of patched tumor-suppressor gene (PTCH) and activation of sonic hedgehog (SHH)
• Risk factors: intermittent sun exposure, radiation Rx, family Hx, ICd
• Often present as pearly papule/nodule w/ telengiectasias central indentation or crater
• Many types exist: nodular BCC (waxy, semitransluscent nodule w/ central depression- rodent ulcer), superficial BCC (psirasiform, scaly lesion), morpheaform (scar-like, white and yellow plaque), fibroepithelioma of Pinkus (pink nodule on back)

Question 8

Behavior of BCC

Answer 8

• Lesions slowly enlarge and ulcerate
• Low metastasis rate (<1%), perineural or intravascular invasion increases risk
• Rx: electrodessication and curretage (ED&C), excision/Mohs, radiation, imuquimod, 5-FU, PDT, vismodegib (SHH inhibitor)

Question 9

Gorlin’s syndrome

Answer 9

• AKA basal cell nevus syndrome (BCNS)
• Often seen in young people w/ 2+ BCC
• Can be heritable

Question 10

Paget’s disease

Answer 10

• Unilateral marginated erythematous crusted plaque on nipple/areola
• Mistaken for eczema of nipple (but is unilateral when eczema should be bilateral)
• Associated w/ invasive or in situ ductal adenocarcinoma of the breast

Question 11

Extrammary Paget’s disease (EMPD)

Answer 11

• Affects sites w/ apocrine glands (vulva, scrotum, inguinal or axillary regions)
• Different types: primary EMPD arises intra-epidermally (most common)
• EMPD w/ underlying apocrine carcinoma
• EMPD w/ underlying GI malignancy
• EMPD w/ genitourinary CA
• EMPD can invade the dermis, which has a high rate of metastasis
• Rx: Mohs/excision, imiquimod, PDT

Question 12

Merkel cell carcinoma

Answer 12

• Red to violet nodule w/ shiny surface, mostly in elderly
• Associated w/ merkel cell polyomarvirus (MCV)
• Aggressive tumor w/ dermal and nodal spread, often has regional lymph node involvement
• Rx: Mohs/excision, radiation

Question 13

Dermatofibrosarcoma Protuberans (DFSP)

Answer 13

• Locally aggressive tumor w/ high recurrence rate, characterized by a bulky, protuberant mass
• Due to transolcations of chroms 17 and 22
• 50-60% on trunk and is slowly progressive, w/ low metastatic potential
• Rx: Mohs surgery/excision