Lecture: Nodular skin diseases

Question 1

Nodules

Answer 1

• solid elevations that extend deep into the dermal or subcu tissue
  
  • inflammatory cells or
  • neoplastic cells

Question 2

DDX for nodules

Answer 2

• infectious
  
  • fungal
  • bacterial
• sterile
• neoplastic

Question 3

DDX fungal nodules

Answer 3

• cryptococcosis
• Histoplasmosis
• Coccidiodomycosis
• Sporotrichosis
• Kerion
• Mycetoma or pseudomycetoma
• Phaeohyphamycosis
• Oomyces (pythiosis)

Question 4

DDX for bacterial nodules

Answer 4

• Deep pyoderma
• acral lick dermatitis (dogs)
• cutaneous bacterial granuloma
• Botrymycosis
• Abscess
• Staphylococcal furunculosis
• Opportunistic or atypical mycobacteria
• Nocardia
• Actinomyces
• Actinobacillus
• Leprosy

Question 5

DDX for sterile nodules

Allergic (cats)

Answer 5

• Eosinophilic granuloma
• mosquito hypersensitivity

Question 6

DDX for sterile nodules

Immune-mediated

Answer 6

• Sterile nodular panniculitis
• sterile nodular granuloma and pyogranuloma
• Plasmacell pododermatitis (cats)

Question 7

DX for nodules

Answer 7

• FNA
• BX for histopath and culture
  
  • take 2 seperate
    
    • don’t clean for histopath
    • clean for culture

Question 8

Mycobacteria

Answer 8

• has few organisms
• doesn’t grow on normal culture media

Question 9

Cultures submitted at UF

Answer 9

• aerobic
• anaerobic
• fungal
• mycobacterial

Question 10

Systemic fungal infections

Answer 10

• cryptococcosis
• histoplasmosis
• blastomycosis
• coccidiomycosis

Question 11

Subcutaneous funcal infections

Answer 11

• Sporotrichosis
  
  • zoonotic
• Opportunistic
  
  • phaeohyphomycosis
  • mycetoma
  • kerion

Question 12

Sporotrichosis

Answer 12

• thermally dimorphic
• present in skin as yeast
• inoculated by a contaminated wound
• large numbers of organisms in feline exudate => WEAR GLOVE​
  
  • ​very few organisms in dogs (hard to dx)
• No immunosuppression necessary

Question 13

Feline sporotrichosis

Answer 13

• draining nodules
  
  • head
  • distal aspects of limbs
  • tail
• history of poor response to AB therapy
• Autoinoculation in other parts by grooming
• most cats develop disseminated disease

Question 14

Feline sporotrichosis

DX

TX

Answer 14

• Usually easy in cats due to large number of organisms
  
  • cytology
  • culture
  • histopath
• TX
  
  • Itraconazole for dogs and cats
    
    • vasculitis, expensive
  • Ketoconazole
  • Iodides
    
    • not well tolerated but cheap

Question 15

Length of treatment for nodular disease

Answer 15

1 month past clinical resolution of signs (up to like 1.5 years)

Question 16

Kerion

Answer 16

• result of innoculating dermatophytes in dermis (reaction to derm infect)
  
  • M. gypseum
  • T. Mentagrophytes
  • Furunculosis

Question 17

Dermatophytic pseudomycetoma

Answer 17

• subcutaneous nodules
• most common on trunk
  
  • frequent ulceration
  • m. canis
• persian cats
• histopath
  
  • pyogranulomatous dermatitis with fungal hyphae
  • tissue grains

Question 18

Pythiosis (Swamp cancer)

Answer 18

• Aggressive, rapidly developing nodules and draining tracts
• Intense pruritus
• easily confused for acral lick granuloma

Question 19

Dogs that come down with pythiosis develop an …….. response

Answer 19

Eosinophilic response

• not cell mediated
• eosinophilic resopnse is itchy

Question 20

Pythium diagnosis

Answer 20

• cytology
  
  • eosinophils, rare hyphae
  • ghost figures
• culture
  
  • from BX sample (UF or LSU) no fridge
• immunohistochemistry

Question 21

Treatment for pythiosis

Answer 21

• mortality 100% without tx
• wide surgical excision
• no ergostrol means we can’t really kill it
• hyperbaric chamber
• vaccine: w/in 2-3 weeks within dx
  
  • changes response to cell-mediated response

Question 22

Lagenidiosis

(oomyces)

Answer 22

• was sprayed in FL water to kill mosquitos (biological thingy)
• looks like pythium clinically
• in water
• same tx as pythium

Question 23

Zygomycosis

Answer 23

• Infection caused by fast growing sapropytic fungi
• Surgical ressection usually necessary
• variable response to drugs
• looks clinically like pythium
• must biopsy and culture

Question 24

Deep pyoderma

Answer 24

• furunculosis
• panniculitis
  
  • s. intermedius
  • pseudomonas
• DX
  
  • clinical signs
  • cytology
  • biopsy
• C & S

Question 25

duration of tx for deep pyo

Answer 25

> 6 weeks (one month past clinical resolution I think)

-typically a couple of months

Question 26

Acral lick dermatitis

(lick granuloma)

Answer 26

• give antibiotic and look for underlying cause
• R/O flea allergy (cephalexin and flea control)

Question 27

Acral lick dermatitis

DX

Answer 27

• BX
• skin scrape
• fungal culture
• Biopsy for histopath and culture
• rule out pythium (esp shepherds and labs)

Question 28

Opportunistic Mycobacteria

Answer 28

• Facultative pathogens
• Non-healing wounds, chronic ulcers, draining tracts
• Cats: lesions often in ventral fat pads
• inguinal area common
• NO SX

​*These cats look awfully but not very clinically sick

Question 29

Opportunistic mycobacteria

Answer 29

• BX large area
  
  • histopath
  • special stains
  • culture

*may have negative tests (repeat)

Question 30

Opportunistic mycobacteria

TX

Answer 30

• Need to do specific sensitivity testing: $$$$$ but necessary
• Fluoroquinolones
• Doxycycline
• Clarithromycin

Question 31

Nocardia

Answer 31

• Skin looks awful like mycobacterium, but cats are also sick
• Culture
• TX
  
  • penicillin and sulfa
  • sometimes Na iodide
• prognosis: guarded

Question 32

Sterile condition

Answer 32

• Foreign body
• Sterile nodular panniculitis
• Sterile pyogranulomas