Case Study

CT – Retrobulbar mass with compression of left ocular bulb in a 9 year old M Rottweiler

This 9 year old intact M Rottweiler mix has a 3-4 month history of left eye erythema and inflammation. Ophthalmologist report: exophthalmia, elevation of 3rd eyelid, 3+ conjunctival episcleral hyperemia, clear anterior chamber, fundic exam showed retrobulbar scleral indentation, non visual, optic nerve atropied, no pain palpated.

DX

retrobulbar mass lesion with severe compression of the left ocular bulb.

Image Interpretation

CT of the head –

An ill-defined soft tissue attenuating mass lesion with multifocal amorphous mineralization is seen within the left orbita, the mass measures 4.3 x 3.8 x 5 cm. A marked mass effect on the left ocular bulb with dorsolateral deviation and compression of the ocular bulb is noted. The pars orbitalis of the left frontal bone presents permeative osteolysis with complete perforation of the calvarium and the left nasal cavity. Permeative osteolysis is noted at the medial aspect of the left zygomatic arch as well.

The right horizontal part of the external ear canal presents a moderately irregular luminal surface. Moderate well-defined linear mineralization of the cartilaginous part of the external ear canals is noted bilaterally. The left mandibular lymph nodes are enlarged and rounded, the short-to-long-axis ratio is increased > 0.5.

Outcome

The mass lesion presents marked aggressive biological behavior compatible with a primary malignant neoplasia in the left orbit with perforation of the calvarial bones. Possible differentials include fibrosacroma, squamous cell carcinoma, adenocarcinoma, melanoma, and other. The secondary regional lymphadenopathy of the left submandibular lymph nodes is
highly suspicious for metastasis.
Further workup would include FNA samples or biopsy of the retrobulbar mass lesion
and the left mandibular lymph node. A surgical option is not without risk due to the
marked bone lysis with perforation of the calvarial bones and is not considered
curative. Radiation therapy would be a possible palliative treatment option with or
without prior cytoreductive exenteration of the orbita.