Difference between revisions of "Respiratory Fungal Infections - Pathology"

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===''Aspergillus fumigatus''===
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[[Image:Aspergillus pneumonia of cattle.jpg|right|thumb|100px|<small><center>Aspergillus hyphae in cattle lung (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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[[Image:Aspergillosis in nasal cavity.jpg|right|thumb|100px|<small><center>Nasal aspergillosis (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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*[[Aspergillus spp.|''Aspergillus fumigatus'']]
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*Most commonly in dogs but also other species
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*Causes [[Nasal cavity - inflammatory#Infectious causes of rhinitis|rhinitis]], often also involves the [[Paranasal sinuses - inflammatory#Infectious causes of sinusitis|frontal sinus]]
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*Chronic necrotising inflammation with friable exudate containing necrotic tissue and fungal hyphae
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* Result in severe neutrophilic [[Nasal cavity - inflammatory|rhinitis]]/[[Paranasal sinuses - inflammatory|sinusitis]]
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*These lesions can be aggressive causing destruction of turbinates and nasal septum
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*Can occur secondary to areas of mucosal compromise eg: adjacent to a space-occupying lesion
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*Can cause pulmonary aspergillosis especially in '''birds''', but also other animals
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**Initiated by inhalation of spores,the most likely source of which is mouldy feed and bedding
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**Given the wide exposure that occurs, it is thought that immunodeficiency may contribute to colonisation with this organism
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**Gross lesions :
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***Multiple discrete grey/ white nodules which develop around fungal colonies
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***Blood vessels can become involved in the lesions -> invasion, haemorrhage or thrombosis
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**Histologically:
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***Granulomatous chronic lesions
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***Macrophages and epithelioid cells
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***Fibrous capsule
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*In horses:
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**[[Nasal cavity - inflammatory#Infectious causes of rhinitis|Nasal aspergillosis]]
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**[[Guttural pouches - inflammatory|Guttural pouch infections]] in horses - fungal plaques form on the adventitia of the carotid arteries can lead to catastrophic haemorrhage following erosion of carotid arteries!
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**Often present with [[Respiratory System Clinical Signs - Pathology#Epistaxis|epistaxis]]
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**May present with neurological dysfunction
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**Rarely extends to other resions: cranium, middle ear, atlanto-occipital joint
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**May extend to [[Paranasal sinuses - inflammatory#Infectious causes of sinusitis|sinuses]]
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===''Cryptococcus neoformans''===
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*[[Yeast-like fungi|''Cryptococcus neoformans'']]
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*Causes a [[Nasal cavity - inflammatory#Infectious causes of rhinitis|granulomatous rhinitis]], gelatinous exudate, [[Lungs - inflammatory#Granulomatous pneumonia|granulomatous pneumonia]]
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*Nodules or destructive masses which often result in facial swelling
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*In severe cases, extension from nasal cavity to involve skin and oral mucosa can occur
 +
*Can invade through adjacent structures, eg: through the cribiform plate into the brain! These cases therefore can present as a primary neurological disease.
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*Microscopic:
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**Large number of fungi and only few macrophages, lymphocytes and giant cells
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===Blastomycosis===
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*Caused by [[Yeast-like fungi|''Blastomyces dermatitidis'']]
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*Occurs mainly in the Americas, Middle East and Africa, occasionally in Europe
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*Mainly in young dogs, occasionally other species
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*Can involve almost any tissue after spread from lungs
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*Gross lesions:
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**[[Lungs - inflammatory#Granulomatous pneumonia|Granulomatous pneumonia]]
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*Microscopic lesions:
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**Yeast fungi with thich walls in nodules with macrophages, neutrophils and giant cells
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===Histoplasmosis===
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*Caused by [[Yeast-like fungi|''Histoplasma capsulatum'']]
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*Gross lesions in lungs:
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**Firm encapsulated granulomas ([[Lungs - inflammatory#Granulomatous pneumonia|granulomatous pneumonia]])
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*Microscopic lesions:
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**Macrophages with inracytoplasmic yeasts
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*Also in other tissues
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===[[Fungi|''Pneumocystis carinii'']]===
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*Important cause of pneumonia in humans associated with immunodeficiency states
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*It has been occasionally reported in young or immunosuppressed animals (e.g. Arabian foals with congenital immunodeficiency)
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*Grossly:
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**Diffuse [[Lungs - inflammatory#Interstitial pneumonia|interstitial]] [[Lungs - inflammatory#Infectious causes of pneumonia|pneumonia]]
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**Patches of firmness or consolidation
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*Histologically:
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**Alveoli are filled with pale staining acidophilic material (= trophozoite and cyst forms of the organism)
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*It is thought that as P. carinii is often present as a latent infection, alveolar macrophages normally control the organism - a process which fails in immunodeficient states

Revision as of 16:23, 31 July 2008

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RESPIRATORY SYSTEM INFLAMMATION



Aspergillus fumigatus

Aspergillus hyphae in cattle lung (Image sourced from Bristol Biomed Image Archive with permission)
Nasal aspergillosis (Image sourced from Bristol Biomed Image Archive with permission)
  • Aspergillus fumigatus
  • Most commonly in dogs but also other species
  • Causes rhinitis, often also involves the frontal sinus
  • Chronic necrotising inflammation with friable exudate containing necrotic tissue and fungal hyphae
  • Result in severe neutrophilic rhinitis/sinusitis
  • These lesions can be aggressive causing destruction of turbinates and nasal septum
  • Can occur secondary to areas of mucosal compromise eg: adjacent to a space-occupying lesion
  • Can cause pulmonary aspergillosis especially in birds, but also other animals
    • Initiated by inhalation of spores,the most likely source of which is mouldy feed and bedding
    • Given the wide exposure that occurs, it is thought that immunodeficiency may contribute to colonisation with this organism
    • Gross lesions :
      • Multiple discrete grey/ white nodules which develop around fungal colonies
      • Blood vessels can become involved in the lesions -> invasion, haemorrhage or thrombosis
    • Histologically:
      • Granulomatous chronic lesions
      • Macrophages and epithelioid cells
      • Fibrous capsule
  • In horses:
    • Nasal aspergillosis
    • Guttural pouch infections in horses - fungal plaques form on the adventitia of the carotid arteries can lead to catastrophic haemorrhage following erosion of carotid arteries!
    • Often present with epistaxis
    • May present with neurological dysfunction
    • Rarely extends to other resions: cranium, middle ear, atlanto-occipital joint
    • May extend to sinuses

Cryptococcus neoformans

  • Cryptococcus neoformans
  • Causes a granulomatous rhinitis, gelatinous exudate, granulomatous pneumonia
  • Nodules or destructive masses which often result in facial swelling
  • In severe cases, extension from nasal cavity to involve skin and oral mucosa can occur
  • Can invade through adjacent structures, eg: through the cribiform plate into the brain! These cases therefore can present as a primary neurological disease.
  • Microscopic:
    • Large number of fungi and only few macrophages, lymphocytes and giant cells





Blastomycosis

  • Caused by Blastomyces dermatitidis
  • Occurs mainly in the Americas, Middle East and Africa, occasionally in Europe
  • Mainly in young dogs, occasionally other species
  • Can involve almost any tissue after spread from lungs
  • Gross lesions:
  • Microscopic lesions:
    • Yeast fungi with thich walls in nodules with macrophages, neutrophils and giant cells

Histoplasmosis

Pneumocystis carinii

  • Important cause of pneumonia in humans associated with immunodeficiency states
  • It has been occasionally reported in young or immunosuppressed animals (e.g. Arabian foals with congenital immunodeficiency)
  • Grossly:
  • Histologically:
    • Alveoli are filled with pale staining acidophilic material (= trophozoite and cyst forms of the organism)
  • It is thought that as P. carinii is often present as a latent infection, alveolar macrophages normally control the organism - a process which fails in immunodeficient states
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