Bacterial Granulomatous Dermatitis

• Usually due to saprophytes
• Grossly:
  • Diffuse or nodular lesions
  • May ulcerate and form drainage fistulas
• Microscopically:
  • Macrophages +/- multinucleated giant cells
  • Caseous necrosis and neutrophils
• Mycobacterial granulomatous or pyogranulomatous lesions
  • Usually caused by Mycobacterium lepraemurium (feline leprosy) or other Mycobacteria
  • Most commonly lesions appear on head, neck and legs
• Botryomycosis