Olfactory neuroblastoma in a horse.

This research article describes a case of olfactory neuroblastoma, a rare type of cancer, in an 11-year-old thoroughbred horse that led to the horse’s euthanasia. The disease was confirmed through various tests, histological examination, and immunohistochemical staining.

Detailed Case Description

• The case was observed in an 11-year-old thoroughbred gelding, a castrated male horse. The animal was euthanized due to a right nasal cavity tumor.
• Upon post-mortem examination, the tumor was found to consist of round to oval cells with a small amount of cytoplasm and hyperchromatic nuclei (nuclei that are more intensely stained).
• Homer-Wright rosettes and pseudorosettes were identified. These are specific arrangements of tumor cells around a central area which are typical for certain types of neural tumors.
• Microcysts, small cysts, were also discovered in the tumor.

Immunohistochemical Analysis

• The tumor cells tested positive for various neural markers – these included Vimentin (a protein expressed in mesenchymal cells), S-100 protein (a family of proteins found in cells derived from the neural crest), and neuron-specific enolase (a glycolytic enzyme found in neurons and cells of the neuroendocrine system).
• The cells also exhibited varying degrees of reactivity to glial fibrillary acidic protein (a type of intermediate filament protein that is a marker of astrocytes in the brain) and microtube-associated protein (proteins that stabilize microtubules).
• This immunohistochemical profile indicated a neurogenic origin of the cells, i.e., they were derived from the nervous tissue.

Diagnosis and Discussion

• Based on these findings, the tumor was diagnosed as an olfactory neuroblastoma, a rare tumor that originates in the olfactory epithelium in the upper part of the nasal cavity.
• The author discusses this type of tumor due to its uncommon occurrence and histological variety, implying that such cases can present diagnostic challenges.