Papules, Pustules, Crust - Derm

Question 1

Flea bite hypersensitivity

Answer 1

Flea allergy dermatitis - papule lesion
Pruritus, erythema, excoriation, self induced alopecia are often seen w crusted papules

Question 2

Sarcoptic mange

Answer 2

Scabies - papule lesion
Intense pruritus, exocoriation, crusts, self induced alopecia are often see w papules

Question 3

Miliary dermatitis

Answer 3

Crusted papular dermatitis - papule lesion
Not a disease but cutaneous reaction pattern common w hypersensitivity in cats

Question 4

Pustule vs crust

Answer 4

Pustule - small circumscribed elevation filled w pus
Crust - cellular debris, dried exudate/blood - left over dried up pustule, vesicle or bulla

Question 5

Infectious pustule or crust

Answer 5

Bacterial**
Superficial pyoderma

Question 6

autoimmune pustule or crust

Answer 6

Pemphigus foliaceus*

Question 7

Sterile pustule or crust

Answer 7

Subcorneal pustular dermatosis - fire ant sting

Question 8

Papule conditions

Answer 8

Flea bite hypersensitivity
Sarcoptic mange
Miliary dermatitis

Question 9

Superficial pyoderma

Answer 9

Bacterial folliculitis, impetigo, exfoliative superficial pyoderma - all caused by staph Pseudintermedius (common) or schliferi (emerging)

Question 10

Bacterial folliculitis

Answer 10

Extremely common in dogs, rare in cats
Affects follicles
Abdomen, groin, medial thighs, axillary - pruritus can be variable

Question 11

Bacterial folliculitis lesion

Answer 11

Erythematous papules —>
Pustules —>
Crusts

Question 12

Bacterial folliculitis in short coated dogs

Answer 12

EXTREMELY common
Skin lesions: Spontaneous alopecia, multi focal - will not expand or coalesce
Found on trunk & extremities
Pruritus is variable, can be mistaken as Dermatophytosis

Question 13

Bacterial impetigo - pyoderma

Answer 13

Puppy pyoderma
Caused by strains of staph that produce exfoliative toxins - common in abdomen
Lesions: pustules, collarettes

Question 14

exfoliative superficial pyoderma

Answer 14

Superficial spreading pyoderma - bacterial exfoliative toxins separate stratum corneum
Lesions:
Large readily expanding collarettes
Peripheral erythema
Hyperpigmented center of chronic lesion
PUSTULES ARE RARE, pruritus varies

Question 15

Cytology for superficial pyoderma
Bacterial folliculitis

Answer 15

Bacterial folliculitis - sample from intact pustules & beneath the crust
Finding - degenerate neutrophils w intracellular bac

Question 16

Cytology of bacterial folliculitis of short coat breeds

Answer 16

Cytology doesn’t yield degenerative neutrophils or bacteria - not reliable

Question 17

Cytology for bacterial impetigo

Answer 17

Sample from intact pustules, edge of epidermal collarette
Findings - degenerate neutrophils w intracellular cocci, free floating epidermal cells due to separation of stratum corneum

Question 18

Cytology of exfoliative superficial pyoderma

Answer 18

Sample from edge of epidermal collarette
Findings - similar bacteria to impetigo but presence is scarce

Question 19

Treatment of superficial pyoderma a

Answer 19

Depends on location
Localized: topical antibacterials - chlorhexidine, benzoyl peroxide, dilute bleach, mupirocin, gentamicin, erythromycin
Oral/systemic antibiotics - cephalosporins, clindamycin, tetracyclines, sulfonamides, floroquinalones, rifampin, chorlamphenicol

Question 20

Localized /topical antibiotics

Answer 20

Chlorhexidine (2-4%)
Benzoyl peroxide
Dilute bleach (1:100)
Mupirocin
Gentamicin
Erythromycin

Question 21

Oral /systemic antibiotics

Answer 21

Cephalosporins
Clindamycin
Tetracyclines
Sulfonamides
Fluoroquinolones
Rifampin
Chloramphenicol

Question 22

XX systemic antibiotics

Answer 22

Bacteria might not be suspectible
Staph = beta lactam, XX for penicillin, amoxicillin, ampicillin
Cephalosporins and potentiated amoxicillin are b lactamase resistant

Question 23

Duration of treatment

Answer 23

At least 3 weeks, 1 week beyond clinical resolution
Floroquinalones - reserve for resistant infections
Combo therapy is ideal method

Question 24

Treatment approach

Answer 24

Superficial pyoderma —> recurs after successful treatment —>investigate underlying causes
- allergic, parasitic, endocrine, chronic steroid use
- no cause = idiopathic recurrent pyoderma

Question 25

TX for idiopathic recurrent pyoderma

Answer 25

1. Frequent and proactive use of topical antibacterial shampoos and/or solutions 2. Immunotherapy with bacterial extracts (i.e. Staphage lysate) – not available now 3. Intermittent systemic antibiotic treatment – controversial treatment

Question 26

Antibiotic resistant pyoderma

Answer 26

Lack of response + new lesions, spreading of old lesions, increased exudation **time to perform a susceptibility test

Question 27

MSRP

Answer 27

Methicillin resistance staph Pseudointermedius Resistant to ALL beta lactamase resistance antibiotics

Question 28

MDR

Answer 28

Multi drug resistant bacteria Resistant to 3 or more classes of antibiotics

Question 29

MSPR is not the same as MRSA

Answer 29

MRSA - methicillin resistant staph aureus Normal flora in humans/horses NOT dogs = can be zoonotic pyodermas

Question 30

Pemphigus foliaceus

Answer 30

Most common autoimmune skin disease in cats and dogs (horses) Autoantibodies target desmosomes in superificial epidermis

Question 31

Breeds predisposed to pemphigus foliaceus

Answer 31

Dogs - GSD, chows, akitas - could be any Cats - any breed

Question 32

Pathogenesis of pemphigus foliaceus

Answer 32

Autoantibodies Neutrophils Pustule + acantholytic keratinocytes Erosion —> crust

Question 33

progression of pemphigus foliaceus lesion

Answer 33

Pustules in irregular shape —> erosion—> crust, most common lesion at presentation

Question 34

distribution of skin lesions in pemphigus foliaceus

Answer 34

Facial** bilaterally symmetrical Nasal planum, nose bridge, periorbital, pinnae (convex or concave) Feet Generalized form

Question 35

DX for pemphigus foliaceus

Answer 35

Cytology Bacterial culture Biopsy

Question 36

Cytology findings for pemphigus foliaceus

Answer 36

nondegenerate neutrophils with acantholytic keratinocytes, no bacteria

Question 37

Findings for bactieral culture for pemphigus foliaceus

Answer 37

to rule out superficial pyoderma (take samples from intact pustules)

Question 38

Biopsy findings for pemphigus foliaceus

Answer 38

often diagnostic if appropriate samples taken (best = intact pustule, second best = lesion with crust, must include crust!)

Question 39

Treating canine pemphigus foliaceus

Answer 39

Oral glucocorticoids - prednisolone /prednisone If not improvement add Azathioprine - ADR: hepatotoxicity, Myelosuppression *monitor* Can add cyclosporine

Question 40

failed treatment of pemphigus foliaceus (+3months)

Answer 40

Time to refer to a dermatoplog

Question 41

Treating feline pemphigus foliaceus

Answer 41

Oral glucocorticoids - prednisolone Cats do NOT tolerate azathioprine - due to Myelosuppression Failed +3 m poor prognosis