Case Study

CT – retrobulbar soft tissue neoplasia in a 10 year old MN DSH cat

This 10 year old MN DDSH cat has a history of OS exophthalmia, elevated nictitans, mild conjunctival hyperemia/thickening, limited ability to retropulse the globe.

Physical Exam: suspect retrobulbar mass

CBC: unremarkable Chemistry: BUN 38, Chol 266, Trig 190, Amy 1337

Reason for Ultrasound Exam: further evaluation prior to possible surgery and staging- patient was taken to surgery by boarded ophthalmologist after CT scan for enucleation and tumor resection.

This 10 year old MN DDSH cat has a history of OS exophthalmia, elevated nictitans, mild conjunctival hyperemia/thickening, limited ability to retropulse the globe.

Physical Exam: suspect retrobulbar mass

CBC: unremarkable Chemistry: BUN 38, Chol 266, Trig 190, Amy 1337

Reason for Ultrasound Exam: further evaluation prior to possible surgery and staging- patient was taken to surgery by boarded ophthalmologist after CT scan for enucleation and tumor resection.

DX

The CT findings are compatible with a retrobulbar soft tissue neoplasia

Image Interpretation

CT of the head –

There is an ovoid space occupying lesion measuring 2 x 2.5 x 2 cm within the retrobulbar space of the left orbita displacing the globe temporodorsally. The lesion shows moderate, non-uniform contrast enhancement. The lesion has a significant mass effect onto the optic nerve. The ipsilateral optic nerve sheath presents a mildly increased diameter cranial to the optic canal. No direct vascular displacement is noted within the optic canal. The globe is macroscopically not infiltrated. No aggressive bony lysis is seen. The left medial retropharyngeal lymph node is mildly enlarged with preserved short to long axis ratio and enhancement pattern.

Outcome

Various types of mesenchymal and epithelial soft tissue neoplasia such as fibrosarcoma, lymphosarcoma and adenocarcinoma are likely differential diagnoses. An optic nerve sheath meningioma is less likely as only an indirect mass effect is noted on the optic nerve.
There is reactive ipsilateral lymph node hyperplasia. No specific features of regional lymph node metastasis are identified.
No evidence of metastatic spread to the lungs or mediastinal lymph nodes was found.