Lesson 5: Pigmentation

• What are pigments?

  Colored substances in cells or tissues
• What are the two main types of pigments?

  • Exogenous Pigments
  • Endogenous Pigments
• What are exogenous pigments?

  Pigments formed outside the body
• What metals are considered exogenous pigments?

  • Silver
  • Bismuth
  • Gold
  • Lead
  • Iron
• What colored substances are classified as exogenous pigments?

  • Carotene
  • Tetracycline
  • Kaolin
  • Tattooing inks
• What fungi are considered exogenous pigments?

  • Monilia
  • Aspergilli
• What condition is caused by inhalation of carbon particles?

  Anthracosis
• What is the most common exogenous pigment seen in tissues?

  Carbon particles
• What color do carbon particles appear in the lungs?

  Black pigments
• How are carbon particles transported in the body?

  By phagocytes
• In which animals is anthracosis common?

  Dogs in urban areas
• What can prolonged exposure to carbon particles result in?

  Grossly visible lesions
• What is the gross description of lungs affected by carbon particles?

  • Mauled appearance
  • Black and gray color
  • Usually affects central lobes
  • Dark lymph nodes
• What is the microscopic description of carbon in tissues?

  • Black granules in cells
  • Found in alveolar and bronchial walls
  • Present in macrophages
  • Bound between lymphoid cells in lymph nodes
• What are the effects of small amounts of carbon particles in lungs?

  Harmless and asymptomatic
• What can large amounts of carbon particles cause in the lungs?

  Fibrosis and pulmonary infection
• What condition results from inhalation of mineral dusts?

  Pneumoconiosis
• What is silicosis caused by?

  Inhalation of silicon dioxide
• What is the gross description of lungs affected by silicosis?

  • Nodular and firm
  • May be pigmented due to anthracosis
• What is the microscopic description of silicosis?

  • Fine crystals in tissues
  • Stimulates fibrous tissue proliferation
  • Forms hard/fibrotic nodules
• What is the effect of silicosis in horses?

  Causes chronic interstitial pneumonia
• What condition is caused by inhalation of iron dusts?

  Siderosis
• What condition is caused by inhalation of asbestos?

  Asbestosis
• What is argyria?

  Deposition of organic silver in tissues
• What was silver used for in the past?

  Treatment of various infections
• What discoloration is caused by chronic lead poisoning?

  Blue-black discoloration of gums
• How can animals experience chronic lead poisoning?

  Ingestion of contaminated pasture and water
• What does bismuth appear as in tissues?

  Faint gray-black pigment
• What was bismuth used for in the past?

  Contrast media for radiographic examination
• What are carotene and xanthophylls?

  • Greenish-yellow pigments
  • Fat soluble
  • Derived from plants
  • Found in egg yolk and body fat
• What happens when tetracyclines are administered to young or pregnant animals?

  Results in grayish pigmentation of teeth
• What is the effect of tattooing ink in tissues?

  • Usually inert
  • Produces no tissue reaction
  • Example: India ink
• What is kaolin?

  A type of clay from aluminous materials
• What condition does kaolin cause in humans?

  Kaolinosis
• Where is kaolin usually deposited in the body?

  In pharyngeal and neck tissues
• What can excessive administration of kaolin cause?

  Granuloma subcutaneously
• What is Monilia also known as?

  Candida albicans
• What characterizes Monilia infection?

  White pseudomembrane on tongue and esophagus
• What are endogenous pigments?

  Produced in the body from altered metabolism
• What are hematins?

  Iron negative pigments from hemoglobin exposure