Residency Program - Case of the Month

History:

A 20-year-old man presented with a 1 year history of slowly progressive left sided proptosis. He denied any visual changes or associated pain. On exam, he had approximately 5 mm of exophthalmos and moderate hypophthalmos.  His extra-ocular movements were grossly intact.  He had a normal cranial nerve exam with intact facial sensation and motor function.

A CT sinus scan was obtained, which showed a 4 cm homogenous well circumscribed thinly calcified mass arising from the diploe of the roof of the left orbit without bony erosion or intracranial invasion. Below is the sinus CT coronal image of thinly calcified mass arising from the diploe of the roof of the left orbit without bony erosion or intracranial invasion.

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The patient then underwent a joint operation by ENT and Neurosurgery for a frontal craniotomy approach for complete resection of orbital roof/skull base lesion and reconstruction with the custom titanium mesh and peri-cranial flap.

Grossly, the tumor was a well circumscribed hyper-ostotic bony lesion emanating from the left orbital roof. Below is the intra-operative photo after complete resection of the COF and reconstruction of the left orbital roof with a custom titanium mesh.

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Microscopic Description:

Microscopic examination shows fusocellular tumor containing calcifications with concentric and acellular mineralization at the center (cementoid type), and other areas presenting recently formed osteoid with peripheral osteoblasts and signs of progressive calcification.  There are no atypias or mitotic figures.

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What is the diagnosis?

A)  Fibrous dysplasia
B)  Cemento - ossifying fibroma
C)  Calcifying epithelial odontogenic tumor
D)  Odontoma

Answer