Changes

*[[Yeast-like fungi|''Cryptococcus neoformans'']]

*[[Yeast-like fungi|''Cryptococcus neoformans'']]

*Causes a [[Nasal Cavity Inflammatory - Pathology#Infectious causes of rhinitis|granulomatous rhinitis]], gelatinous exudate, [[Lungs - inflammatory#Granulomatous pneumonia|granulomatous pneumonia]]  

*Causes a [[Nasal Cavity Inflammatory - Pathology#Infectious causes of rhinitis|granulomatous rhinitis]], gelatinous exudate, [[Lungs Inflammatory - Pathology#Granulomatous pneumonia|granulomatous pneumonia]]  

*Nodules or destructive masses which often result in facial swelling

*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

*In severe cases, extension from nasal cavity to involve skin and oral mucosa can occur

*Can involve almost any tissue after spread from lungs

*Can involve almost any tissue after spread from lungs

*Gross lesions:

*Gross lesions:

**[[Lungs - inflammatory#Granulomatous pneumonia|Granulomatous pneumonia]]

**[[Lungs Inflammatory - Pathology#Granulomatous pneumonia|Granulomatous pneumonia]]

*Microscopic lesions:

*Microscopic lesions:

**Yeast fungi with thich walls in nodules with macrophages, neutrophils and giant cells

**Yeast fungi with thich walls in nodules with macrophages, neutrophils and giant cells

*Caused by [[Yeast-like fungi|''Histoplasma capsulatum'']]

*Caused by [[Yeast-like fungi|''Histoplasma capsulatum'']]

*Gross lesions in lungs:

*Gross lesions in lungs:

**Firm encapsulated granulomas ([[Lungs - inflammatory#Granulomatous pneumonia|granulomatous pneumonia]])

**Firm encapsulated granulomas ([[Lungs Inflammatory - Pathology#Granulomatous pneumonia|granulomatous pneumonia]])

*Microscopic lesions:

*Microscopic lesions:

**Macrophages with inracytoplasmic yeasts

**Macrophages with inracytoplasmic yeasts

*It has been occasionally reported in young or immunosuppressed animals (e.g. Arabian foals with congenital immunodeficiency)

*It has been occasionally reported in young or immunosuppressed animals (e.g. Arabian foals with congenital immunodeficiency)

*Grossly:

*Grossly:

**Diffuse [[Lungs - inflammatory#Interstitial pneumonia|interstitial]] [[Lungs - inflammatory#Infectious causes of pneumonia|pneumonia]]  

**Diffuse [[Lungs Inflammatory - Pathology#Interstitial pneumonia|interstitial]] [[Lungs Inflammatory - PathologyLungs Inflammatory - Pathology#Infectious causes of pneumonia|pneumonia]]  

**Patches of firmness or consolidation

**Patches of firmness or consolidation

*Histologically:

*Histologically:

**Alveoli are filled with pale staining acidophilic material (= trophozoite and cyst forms of the organism)

**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

*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