Maxillary unicystic ameloblastoma in a 6-week-old filly evaluated with computed tomography.

The research article discusses a case where a 6-week-old Thoroughbred filly was diagnosed with maxillary unicystic ameloblastoma using computed tomography. The finding, being the first of its kind, highlights the importance of CT scans in identifying and defining masses in animals for more informed decision making.

The Case

• A 6-week-old Thoroughbred filly presented with an expansive tumor-like growth over its right nasal passage, causing respiratory problems.
• The location of the mass as identified on the filly’s skull radiographs, was above the right upper premolars, causing distortion in the right nasal cavity.

Computed Tomography (CT) Scan Findings

• A detailed computed tomography (CT) scan was done to gain further clarity about the mass. The CT scan revealed that the mass, although locally extensive, displayed relatively benign characteristics.
• The central location of the mass was determined to be on the tooth root apices of the deciduous second premolar.
• The CT scan further revealed that the mass expanded into the right nasal cavity, blocking the meatuses and causing a shift of the nasal septum to the left side.

Regrettable Outcome and Histopathological Examination

• The decision was taken against surgical excision as the athletic future of the filly was considered. Unfortunately, the owners decided to euthanize the filly.
• The mass was found consistent with unicystic ameloblastoma upon histopathological examination.
• The mass was intermittently lined with palisading, columnar basal cells (ameloblast-like cells) layered over an area containing star-shaped cells in loose connective tissue.

Significance of the Findings

• This case is significant as it’s the first reported case of a CT scan identifying an equine ameloblastoma.
• While histopathology was critical for the definitive diagnosis, the CT scan played an essential role in clearly defining the mass’s origin and revealing its locally extensive, cystic nature.
• The findings from the CT scan ultimately allowed for an informed decision regarding the horse’s treatment.