Avian Histopathology Learning Module 1–Learning Component 4 Features or “Things” Viral, Bacterial, Mycotic
Learning Module 1 Learning Component 4...• Bacterial (Staphylococcal) Osteomyelitis • Multifocal to Diffuse Necrosis and Inflammation in Physis and Diaphysis of Bone • Intralesional
In this fourth Learning Component in Learning Module 1, we will look at features or “things” that indicate viral, bacterial, and mycotic infections.
Example – Infectious Laryngotracheitis
• Broiler• Diffuse Tracheal Necrosis• Fibrinoheterophilic Exudate in Lumen• Synctial Cells with I/N Inclusions
Presenter
Presentation Notes
This case of infectious laryngotracheitis in a broiler illustrates diffuse tracheal necrosis, fibrinoheterophilic exudate, and synctial cells (multinucleated giant cells). The nuclei of the synctial cells contain intranuclear (I/N) inclusions. This combination of synctial cells and I/N inclusions is diagnostic for laryngotracheitis.
A B
C D
Presenter
Presentation Notes
A is a low power view of a trachea showing diffuse epithelial necrosis with accumulation of exudate in the lumen. B is a higher magnification showing the luminal exudate. C shows a synctial cell within the exudate. D shows inclusions located in the nuclei of a synctial cell.
Presenter
Presentation Notes
This higher magnification of a synctial cell shows the intranuclear inclusions. This finding is diagnostic for infectious laryngotracheitis.
This case of fowl pox illustrates epithelial hyperplasia, also referred to as acanthosis since this is squamous epithelium. Pox is characterized also by ballooning (hydropic) degeneration of epithelial cells, and intracytoplasmic (I/C) inclusions bodies. Necrosis and inflammation are components of these lesions, but, by themselves, are not diagnostic for pox because necrosis and inflammation may occur following nearly any injury to epithelium.
A B
C D
Presenter
Presentation Notes
A is a low power view of skin showing necrosis – an ulcer – of surface epithelium, inflammation of the dermis, and epithelial hyperplasia. B is a higher magnification showing caseous necrosis (upper left corner), inflammation, and epithelial hyperplasia. C shows hyperplastic epithelial cells, many of which contain eosinophilic intracytoplasmic inclusions. D is a higher magnification of C showing the large intracytoplasmic inclusions.
Presenter
Presentation Notes
This higher magnification of the lesions shown in D from the previous slide shows in more detail the intracytoplasmic inclusions (arrows). The clear vacuolation of the cells is due to ballooning (hydropic) degeneration.
Example –Osteomyelitis
• Broiler, Young Bird• Bacterial (Staphylococcal) Osteomyelitis• Multifocal to Diffuse Necrosis and
Inflammation in Physis and Diaphysis of Bone
• Intralesional Bacteria
Presenter
Presentation Notes
This case of osteomyelitis in young broilers is an example of a lesion that includes bacterial colonies. We refer to bacteria within lesions as being intralesional. This multifocal to diffuse osteomyelitis was caused by infection with Staphylococcus.
A B
C D
Presenter
Presentation Notes
A is a low power view of bone showing extensive areas of necrosis. Numerous bacteria, as shown in D, are within these necrotic areas. B is a higher magnification of the zone of hypertrophy in the physis showing numerous bacteria (the dark blue staining objects). See image D for a higher magnification. C shows an area of necrosis (black arrow) and bacteria (red arrow). D is a higher magnification of the bacteria in a region of necrosis within a vascular channel in the zone of hypertrophy of the physis.
Example - Orchitis
• Broiler Breeder• Multifocal Necrosis of Seminiferous
Tubules with Intralesional Bacteria
Presenter
Presentation Notes
This case of orchitis (inflammation of the testis) in a broiler breeder illustrates lesions of multifocal necrosis with intralesional bacteria in seminiferous tubules.
A
B C
Presenter
Presentation Notes
A is a view of normal seminiferous tubules. B is a low power view showing multiple focal areas of necrosis of the seminiferous tubules. C is a higher magnification of a necrotic seminiferous tubule showing the intralesional bacteria.
Example – Crop Mycosis
• Hyperplasia (Acanthosis) of Epithelium• Ballooning (Hydropic) Degeneration of
Epithelial Cells• Accumulation of Keratin and Other Debris
on Surface• Intralesional Pseudohyphae of Candida
sp.
Presenter
Presentation Notes
This case of crop mycosis will show epithelial hyperplasia (acanthosis), hydropic or ballooning degeneration of epithelial cells, accumulation of excess keratin and debris on the epithelial surface of the crop, and intralesional pseudohyphae typical of Candida.
A B
C D
Presenter
Presentation Notes
A is a low power magnification showing epithelial hyperplasia (acanthosis) and accumulation of keratin and debris on the epithelial surface of the crop. B is a higher magnification of A and shows the ballooning degeneration of epithelial cells. Careful examination of the keratin on the surface reveals pseudohyphae of Candida. C and D are images from slides stained with Gomori’s methenamine silver showing numerous pseudohyphae.
Presenter
Presentation Notes
This is high power magnification of B from the previous slide. Pseudohyphae can be seen in this H&E stained section. Note the prominent ballooning (hydropic) degeneration.
