Skin Infections & Rashes

Question 1

What factors are important?

Answer 1

• Overall appearance of skin
• Rash distribution/location
• Rash pattern
• Local organization of lesion
• Lesion morphology (shape, size, warmth, tenderness, blanching)

Question 2

Macule

Answer 2

flat, less than 1cm

Question 3

Papule

Answer 3

elevated, less than 1cm

Question 4

Plaque

Answer 4

elevated, flat top, more than 1cm

Question 5

Nodule

Answer 5

domed/rounded, more than 1cm

Question 6

Pustule

Answer 6

discrete, pus-filled lesion

Question 7

Vesicle

Answer 7

elevated, less than 1cm, serous fluid

Question 8

Bulla

Answer 8

elevated, greater than 1cm, serous fluid

Question 9

Petechiae

Answer 9

purpuric macules, up to 2mm, don’t blanch

Question 10

Palpable purpura

Answer 10

elevated, firm, hemorrhagic papules or plaques

Question 11

Maculopapular

Answer 11

Combination of macules and papules

Question 12

Morbilliform

Answer 12

measles-like

Question 13

scarlatiniform

Answer 13

resembling scarlet fever; sandpaper appearance

Question 14

Which diagnostic studies are relevant for rashes?

Answer 14

1. Culture
2. Histopathology
3. Serology

Question 15

What skin abnormalities are associated with primary bacterial infection?

Answer 15

Cellulitis, furuncles, skin lesions

Question 16

What mechanisms are involved in the pathogenesis of bacterial infections?

Answer 16

1. local replication/local inflammation
2. circulating exotoxins (SSSS)
3. immunologic mechanisms
4. manifestation of DIC (disseminated intravascular coagulation)

Question 17

What does cellulitis look like?

Answer 17

• Area of edema, warmth, redness
• Infection of SQ tissue and dermis
• Swollen LN, fever, chills, malaise possible
• Pathogens: Staph. aureus, Strep. pyogenes

Question 18

What pathogens should be considered?

Answer 18

Both mouth and skin flora

Common pathogens: pasteurella, anaerobes, Staph. aureus, GAS

Often polymicrobial

Question 19

What pathogens cause periorbital cellulitis?

Answer 19

Sinus and skin flora

Common: Strep. pneumoniae, H. influenzae, M. catarrhalis, S. aureus

RULE OUT ORBITAL CELLULITIS

Question 20

erysipelas

Answer 20

Superficial form of cellulitis with LN involvement

Pathogen: Strep. pyogenes (GAS)

Question 21

necrotizing fasciitis

Answer 21

• progressive, rapidly spreading infection of deep fascia
• secondary necrosis of SQ tissues
• Strep. pyogenes, other bacteria
• Rx: surgical debridement

Question 22

furuncle

Answer 22

boil, most commonly caused by Staph. aureus

Question 23

impetigo

Answer 23

honey-crust scabs on baby’s face caused by GAS or Staph. aureus

Question 24

bullous impetigo

Answer 24

flaccid bullae caused by staph. aureus