02a: Skin Cancer and Infections

Question 1

(X) genetic syndrome is associated with basal cell carcinoma. It has (Y) inheritance pattern with mutation in:

Answer 1

X = Gorlin
Y = AD

Patch gene (tumor suppressor)

Question 2

Gorlin syndrome: in addition to hundreds of (X) skin lesions, these patients have which other symptoms/features?

Answer 2

X = basal cell carcinoma

Palmar/plantar pits, jaw cysts, skeletal abnormalities, meningiomas

Question 3

Most common of all cancers:

Answer 3

Basal cell carcinoma

Question 4

Hallmark features of Basal cell carcinoma

Answer 4

Pearly appearance and Telangiectasia on surface

Question 5

Which histological feature is diagnostic of basal cell carcinoma?

Answer 5

Retraction/clefting in stroma (mucin production increased in BCC; leaves pocket of mucin that appears as clearing when slide is prepped)

Question 6

List the three forms of basal cell carcinoma. Star the types that are easiest to miss.

Answer 6

1. Nodular
2. Superficial*
3. Infiltrative*

Question 7

Metastatic basal cell carcinoma (or non-surgical candidates) can be treated with which (topical/oral/IV) medication?

Answer 7

Oral (once daily)

Vismodegib

Question 8

Vismodegib side effects:

Answer 8

1. TERATOGEN
2. Altered taste
3. Hair loss
4. Muscle spasms

Question 9

35 yo man has ill-defined pink, scaly thin papule with overlying white crust on his face. It has gritty/sand-paper texture. What’s the likely diagnosis?

Answer 9

Actinic Keratosis (precancerous lesion for Squamous Cell Carcinoma)

Question 10

Actinic Keratosis: most common mutation seen in these lesions is

Answer 10

p53

Question 11

T/F: Best Rx option for patient with multiple actinic keratoses on scalp is liquid nitrogen.

Answer 11

False - not good for large field; mainly used to treat individual lesions

Question 12

Imiquimod is (oral/IV/topical) drug that is used to treat (X) via which mechanism?

Answer 12

Topical;
X = actinic keratoses

Promotes immune (interferon) response in treated areas

Question 13

(X) drug for actinic keratoses is very effective (only few days of therapy) but has disadvantages due to:

Answer 13

X = Ingenol (topical)

Direct cytotoxicity (skin irritation) and expensive

Question 14

Hallmark mutation of Head/Neck Squamous Cell Carcinoma

Answer 14

p53 (47%)

Question 15

Itchy, skin-colored papules with central umbilication on penis and scrotum. What’s the likely infectious agent?

Answer 15

Molluscum Contagiosum (Pox virus)

Question 16

T/F: Molluscum Contagiosum lesions are confined to genitalia.

Answer 16

False - patient can inoculate different parts of body by scratching; common outbreaks in daycares/schools but usually sexually transmitted in adults

Question 17

Multiple, large Molluscum Contagiosum lesions on face/scalp of patient. May be a sign of:

Answer 17

Immunosuppression (HIV)

Question 18

Bullous impetigo infectious cause is usually:

Answer 18

S. aureus

Question 19

Non-bullous impetigo infectious cause is usually:

Answer 19

S. aureus and S. pyogenes

Question 20

Bullous impetigo, usually as result of (X) microbe, pathogenesis:

Answer 20

X = S. aureus

Exfoliative toxins (A-D) bind and degrade desmoglein 1 (keratinocytes lose close contact, form bullae)

Question 21

T/F: Bullae in bullous impetigo can be easily ruptured.

Answer 21

True - Desmoglein 1 prominent in superficial epidermis

Question 22

Honey-colored crusting typically signifies (bullous/non-bullous) impetigo.

Answer 22

Non-bullous

Question 23

Ulcerated form of non-bullous impetigo is referred to as:

Answer 23

Ecthyma (deeper impetigo, extending to dermis)

Question 24

First-line Rx for impetigo:

Answer 24

Mupirocin 2% ointment

Question 25

Second-line Rx for impetigo:

Answer 25

1. Beta-lactamase resistant penicillin
2. Macrolide
3. First/second gen cephalosporin

Question 26

Rx for Ecthyma caused by S. aureus impetigo:

Answer 26

1. Beta-lactamase resistant penicillin

2. First gen cephalosporin

Question 27

Recurrent anogenital furuncles are likely caused by:

Answer 27

Anaerobic bacteria

Question 28

T/F: Not all furuncles/carbuncles are treated with antibiotics.

Answer 28

True - management usually includes culture, warm compress, maybe incision/drainage

Question 29

In which situations would a furuncle/carbuncle be treated with systemic antibiotics?

Answer 29

1. Around nose/nares or auditory canal
2. Large, recurrent lesions or surrounding cellulitis
3. Lesions unresponsive to local care

Question 30

Most common causes of cellulitis in immunocompetent adults:

Answer 30

1. S. pyogenes
2. S. aureus

(usually lower extremities)

Question 31

Most common causes of cellulitis in kids:

Answer 31

S. aureus (usually head/neck)

Question 32

Most common causes of cellulitis in diabetics:

Answer 32

Polymicrobial

Question 33

Cellulitis Rx:

Answer 33

1. Immobilization/elevation; wound care

2. G-positive coverage (broad-spectrum important for diabetics due to polymicrobial infection)

Question 34

60 yo female with itchy red lesions under her breasts that are worse in summer. You notice multiple tiny, erythematous papules that coalesce under breast crease. Diagnosis?

Answer 34

Candida infection (C. albicans)

Fungal infections worse in summer (heat, moisture) and small papules are characteristic “satellite lesions”

Question 35

6 mo child presents with diaper dermatitis. Appears erythematous with satellite lesions. What’s the likely etiology?

Answer 35

Candidiasis

Question 36

First-line Candidiasis Rx:

Answer 36

Topical nystatin or clotrimazole

Question 37

Second-line Candidiasis Rx:

Answer 37

PO azoles

Question 38

35 yo presents with inflammatory scalp plaques, hair loss, and some black dots on scalp. What’s at the top of your differential?

Answer 38

Tinea capitis

Black dots are due to broken hair shafts

Question 39

5 yo boy presents with multiple large annular scaling plaques on trunk. There is central clearing and you notice he keeps scratching them. What is at the top of your differential?

Answer 39

Tinea corporis

Question 40

You notice your patient has yellow, thick and crumbly toe nails as well as scaly erythema on the soles of his feet. What is the likely etiology?

Answer 40

Tinea unguium (onychomycosis) of toe nailes and tinea pedis on feet

Question 41

Diagnosis of dermatophytosis involves:

Answer 41

Scraping debris off lesion and using KOH prep (look for septate hyphae)

Question 42

T/F: Dermatophytoses can collectively be treated with topical antifungals.

Answer 42

False - most can, but some (nails, scalp) require oral antifungals due to tough keratins