Primary intracranial squamous cell carcinoma in a mule

Area of Science:

• Veterinary Pathology
• Comparative Oncology
• Neuro-oncology

Background:

• Primary intracranial squamous cell carcinoma (PISCC) is a rare human malignancy.
• PISCC typically arises from pre-existing epidermoid or dermoid cysts.
• This tumor has not been previously documented in animal species.

Purpose of the Study:

• To document the first reported case of PISCC in an animal.
• To detail the clinical, pathological, and immunohistochemical features of this animal PISCC.
• To establish PISCC as a differential diagnosis for central nervous system diseases in animals.

Main Methods:

• Clinical case presentation of a 15-year-old male mule with bilateral blindness.
• Gross necropsy examination revealing a central nervous system mass.
• Histopathological and immunohistochemical analysis of the neoplastic tissue.

Main Results:

• A multilobulated, whitish mass surrounded key neural structures (optic nerve, chiasm, pituitary, trigeminal nerve).
• Histology showed neoplastic pleomorphic squamous epithelial cells forming nests with keratin pearls.
• Immunohistochemistry confirmed neoplastic cells were positive for cytokeratin and negative for vimentin and alpha fetoprotein.

Conclusions:

• Primary intracranial squamous cell carcinoma can occur in animals.
• This condition can manifest with significant neurological deficits.
• PISCC should be considered in the differential diagnosis of animal central nervous system neoplasms.