Common Infections of the Skin

Question 1

HSV 1 and 2

Answer 1

Grouped vesicles on an erythematous base
Persists in sensory ganglia leading to recurrent infections
Can see erosions and crusting sometimes

Question 2

Varicella

Answer 2

Morphology like “a dewdrop on a rose petal”
Initial lesions papules which become vesicles
Vesicles then crust over
May heal with scarring
Crops of lesions in all stages

Question 3

Herpes zoster

Answer 3

Prodrome of neuritic pain
Acute vesicles then crusted papules
Distribution is unilateral and dermatomal
Grouped vesicles on an erythematous base

Question 4

Non bullous impetigo

Answer 4

Scaling honey crusted non bullous impetigo

Superficial infection of epidermis caused by group A strep or s aureus

Question 5

Bullous impetigo

Answer 5

Vesicles and bullae
Clear or slightly yellow fluid
Shallow erosions if bullae break
Caused by S aureus

Question 6

Bedbugs

Answer 6

Cause erythematous papules, vesicles, nodules
Will often bite on body and head and neck area
Itchy
Groups of 3 or 4

Question 7

Pityrosporum folliculitis

Answer 7

Monomorphous papules without comedones
Sweaty people
Caused by normal healthy yeast that has gone into the hair follicle
Not very inflamed

Question 8

Pseudomonas folliculitis

Answer 8

History of hot tub exposure
Inflammatory follicular-based papules and pustules
Involves exposed areas
Self limited

Question 9

Tinea corporis

Answer 9

Annular scaling edge
Well demarcated plaques
Central clearing
Single or multiple lesions

Question 10

Pityriasis versicolor

Answer 10

Not a dermatophyte infection
Well marginated round scaling brown or pale minimally elevated papules
Yeast
Common in young adults

Question 11

Secondary syphilis

Answer 11

2-6 months after primary infection
First eruption is macular then can be papulosquamous, pustular or acneiform
Look for involvement of palms and soles

Question 12

Verruca vulgaris

Answer 12

Common warts
Firm, hyperkeratotic papules with clefted surface and vegetations
Red or brown dots from thrombosed capillary loops
Transmitted by skin to skin contact

Question 13

Molluscum contagiosum

Answer 13

Skin coloured umbilicated papules

Mollusca undergoing spontaneous regression may have an erythematous halo/ezcema

Question 14

Scabies

Answer 14

Widespread pruritic eczematous eruption
Spares head and neck usually
Can take 6 weeks from exposure
Burrows: serpiginous track with spot at end
Nodules: red/brown nodules in axillary area and groin, can persist after infection is clear

Question 15

Norwegian scabies

Answer 15

Heavy infestation of scabies mite in immunocompromised hosts

Highly contagious and requires repeated treatments

Question 16

Pediculosis corporis

Answer 16

Body louse
Eczematous eruption
No primary lesions
Secondary infection common
Look in seams of clothing for louse and nits
Very itchy - a lot of crusting and superficial erosions

Question 17

Pediculosis Capitis

Answer 17

Head lice
Itchy
Bite reactions include eczema, excoriation, lichenification

Question 18

Tinea cruris

Answer 18

Well marginated scaling red plaques with central clearing
Papules and pustules may be present at margins
Occurs in inguinal region and on thighs

Question 19

Candidal intertrigo

Answer 19

Erythematous plaques with satellite papules and pustules
Found in moist environment
From yeast

Question 20

Erythasma

Answer 20

Sharply marginated patch

Redilection for folds

Question 21

Inverse psoriasis

Answer 21

Well marginated erythematous plaques
Check for psoriasis elsewhere (scalp, nails, etc)
Tends not to scale like psoriasis elsewhere

Question 22

Things that Staph aureus can cause

Answer 22

Impetigo
Ecthyma
Cellulitis
Folliculitis
Furuncles (boils)
Carbuncles
Abscesses

Question 23

Things HPV can cause

Answer 23

Flat warts
Plantar warts
Verruca vulgaris
Periungual warts
Condylomata

Question 24

Tinea unguium

Answer 24

Thick yellow dystrophic toenails or fingernails
Toes more often involved
Genetic predisposition
Often associated with tinea pedis

Question 25

Tinea pedis

Answer 25

Athlete’s foot
Interdigital (scaling, maceration, fissures) and moccasin (well marginated, fine scale, hyperkeratosis) types
Inflammatory or bullous types