Dermatology - Skin infections

Question 1

Superficial skin infection involving the upper dermis; raised sharply demarcated lesion

Answer 1

Erysipelas

Question 2

What are the non-purulent skin infections?

Answer 2

• Erysipelas
• Cellulitis

Question 3

What are the purulent skin infections?

Answer 3

• furuncle
• carbuncle
• abscess

Question 4

Risk factors for skin and soft tissue infections

Answer 4

• chronic lymphedema
• local skin defects (tinea pedis, burn wounds)
• diabetes
• immunodeficiency
• IV drug up

Question 5

Local infection of the deep dermis and subcutaneous tissue; poorly defined lesion with induration

Answer 5

Cellulitis

Question 6

Clinical features of skin infections

Answer 6

• erythema
• edema
• warmth
• tenderness

Question 7

Inflammation or infection of the lymphatic channels, which often occurs secondary to an infectious source at a location distal to the lymphatic channel.

Answer 7

Lymphangitis

Question 8

Most common cause of lymphangitis

Answer 8

Streptococcus pyogenes (Group A Strep)

Question 9

The most common fungal cause of lymphangitis

Answer 9

Sporothrix schenckii

Question 10

Red streaks radiating from the skin lesion and following the direction of lymphatic vessels

Answer 10

Lymphangitis

Question 11

Swollen, tender, regional lymph nodes

Answer 11

Lymphadenitis

Question 12

Most common point of entry for the pathogen

Answer 12

A small skin lesion

Question 13

Most common cause of non-purulent skin and soft tissue infections (erysipelas and cellulitis)

Answer 13

Group A Strep

Question 14

Highly contagious infection of the superficial edipermis with honey yellow crusts and bullae formation

Answer 14

Impetigo

Question 15

Localized inflammation of the hair follicle or sebaceous glands that is limited to the epidermis

Answer 15

Folliculitis

Question 16

Pseudomonal folliculitis that appears 8-48 hours after exposure to contaminated water; usually self limiting and does not require ABX.

Answer 16

Hot tub folliculitis

Question 17

Deep folliculitis beyond the dermis with abscess formation in the subcutaneous tissue.

Answer 17

Furuncle

Question 18

Confluent folliculitis that forms an inflammatory mass

Answer 18

Carbuncle

Question 19

Severe complications of facial furuncles

Answer 19

• periorbital cellulitis
• cavernous sinus thrombosis

Question 20

A subcutaneous collection of pus in the scrotal region usually a result of inflamed hair follicles which may progress to Fournier gangrene

Answer 20

scrotal abscess

Question 21

A condition of necrotizing fasciitis affecting the genital or perianal areas

Answer 21

Fournier gangrene

Question 22

Soft tissue ultrasound findings of skin abscesses

Answer 22

hypo-echoic, heterogenous fluid collection with posterior enhancement

Question 23

Treatment of purulent skin and soft tissue infection

Answer 23

Incision and drainage (no ABX are required unless there are systemic signs of infection)

Question 24

An aggressive, life-threatening infection involving necrosis of the tissue

Answer 24

necrotizing soft tissue infection

Question 25

A rapidly progressive infection resulting in extensive necrosis of superficial and deep fascia overlying subcutaneous fat

Answer 25

Necrotizing fasciitis

Question 26

Fournier gangrene is a necrotizing fasciitis that can spread to

Answer 26

anterior abdominal wall and gluteal muscles

Question 27

Culture for necrotizing fasciitis is obtained via

Answer 27

deep tissue culture during surgical exploration

Question 28

Clinical features of necrotizing fasciitis

Answer 28

- systemic symptoms (fever, chills, altered mental status) - diffuse erythema - extreme tenderness (pain out of proportion) - significant induration - crepitus (production of methane and CO2 by the bacteria) - purple discoloration (skin necrosis) - bullae - loss of sensation (paresthesias)

Question 29

Necrotizing fasciitis spreads along ____ before spreading to the superficial cutaneous tissue. This is why pain is out of proportion to local findings.

Answer 29

spreads along the fascia first

Question 30

If clinical features suggest necrotizing fasciitis, start management with

Answer 30

- immediate surgical exploration with debridement - broad spectrum ABX

Question 31

What confirms the diagnosis of necrotizing fasciitis?

Answer 31

surgical exploration with debridement to obtain deep tissue samples for gram stain, cultures and histopathology

Question 32

Complications of necrotizing fasciitis

Answer 32

- severe necrosis requiring amputation of the affected limb - sepsis - DIC - organ dysfunction (AKI) - death - high mortality rate even with adequate treatment