Usmle Recall Dermatology

Front 1

Name four causes of hair follicle plugging leading to acne.

Back 1

1. excess sebum production
2. overgrowth of Proprionibacterium acnes
3. inflammation
4. abnormal keratin production

Front 2

What first-line topical treatments are available, and how do they work?

Back 2

1. Benzoyl peroxide (decreases P. acne)
2. Retinoic acid (decreases abnormal keratin production)
3. topic antibiotics erythromycin and clindamycin (decrease microbial irritants that cause local inflammation)

Front 3

When should systemic treatment be considered?

Back 3

If papules, pustules, or nodules are found on physical exam.

Front 4

What systemic agents are commonly used?

Back 4

erythromycin and tetracycline

Front 5

When is tetracycline contraindicated?

Back 5

Pregnancy and young children

Front 6

What medical treament is available for severe nodular cystic acne with scarring?

Back 6

isotretinoin (accutane)

Front 7

What is an absolute contraindication to Accutane?

Back 7

Pregnancy

Front 8

What should be ordered before prescribing Accutane or tetracycline for a female patient?

Back 8

Pregnancy test

Front 9

What two additional measures are suggested for female patients receiving Accutane?

Back 9

1. use oral contraception or the most effective available contraception from 1 month prior until 1 month after discontinuation of the therapy
2. avoid systemic antibiotics (owing to possible risk of oral contraception failure)

Note, however from Mayoclinic.com
The effects of antibiotics on birth control pills may be overstated — except in the case of one antibiotic, rifampin. Studies clearly show that rifampin decreases the effectiveness of birth control pills in preventing ovulation. However, rifampin isn't a widely used antibiotic. Chances are you wouldn't be taking it unless you had tuberculosis or had tested positive for the disease.

Front 10

What is actinic keratosis?

Back 10

A precancerous lesion characterized by clonal prliferation of atypical keratinocytes.

Front 11

What are the two risk factors?

Back 11

1. sun-exposed skin
2. immunocompromise

Front 12

How does it present?

Back 12

firm, well-marginated, reddish papule, diameter <1cm, with rough feel (like sandpaper); typically changes to yellow brown color when exposed to UV light

Front 13

How is the diagnosis made?

Back 13

biopsy

Front 14

What treatment is available?

Back 14

cryosurgery

Front 15

What are two alternative treatments?

Back 15

topical 5-fluorouracil cream, electrocautery

Front 16

What are untreated patients at risk for?

Back 16

squamous cell carcinoma (1:1000 risk)

Front 17

What organism causes candidiasis?

Back 17

candida albicans

Front 18

Who is at risk?

Back 18

immunosuppressed patients, persons with diabetes, obese patients

Front 19

How does it present on the skin?

Back 19

itching and burning sensation; beffy-red lesions of varying sizes on warm, most areas of the body (e.g. inner thiagh

Front 20

How are oral and skin candidiasis diagnosed?

Back 20

microscopic visualization of yeast and pseudohyphae using 10% potassium hydroxide

Front 21

What is the treatment for skin lesions?

Back 21

nystatin cream or ketoconazole cream

Front 22

What is the treatment for oral candiasis?

Back 22

nystatin liquid ("swish and swallow")

Front 23

What causes cellulitis?

Back 23

group A beta-hemolytic strep (Strep pyogenes) and Staph aureus

Front 24

What are the risk factors?

Back 24

diabetes, immunosuppression, skin trauma, lymphatic and venous obstruction

Front 25

Where does cellulitis commonly appear?

Back 25

lower extremities

Front 26

What should be included in the workup?

Back 26

CBC, gram stain and cultures of skin lesions, blood cultures, possibly skin biopsy

Front 27

What is the treatment?

Back 27

antibiotics (oxacillin or a cephazolin), best rest, elevate affected area, and treat underlying conditions if present.

Front 28

Why does oxacillin or cephazolin work in treating cellulitis?

Back 28

Cellulitis is generally caused by Staph aureus and/or Strep pyogenes. Staph aureus makes a pencillinase (aka. beta-lactamase, which destroys the structure of the pencillin). Oxacillin is a pencillinase-resistant antibiotic (in the same class as methicillin, nafcilin and dicloxacillin). Cephazolin is a 1st generation cephalosporin which has a beta-lactam ring much more resistant to beta-lactamases.

Front 29

What additional treatment may be required in a person with diabetes?

Back 29

anaerobic antibiotics (e.g. metronidazole or clindamycin) due to increased risk of polymicrobial infection.

Front 30

What would metronidazole or clindamycin work?

Back 30

Metronidazole is antiprotozoal (Giardia, Entamoeba, Trichomonas, Gardnerella vaginalis) and also against anaerobes (Bacteroides, Clostridium).
Clindamycin treats anaerobic infections mainly (e.g. Bacteroides fragilis, Clostridium perfringens)