Background: Giant cell tumor of bone originating from the connective tissue within the bone marrow is benign but locally aggressive lesion. In all, 90% of the cases involve the epiphysis of long bones and less than 2% involve the skull. Giant cell tumors of the skull occur most frequently in the sphenoid and temporal bones, and very rarely in the ethmoid, frontal, parietal, and occipital bones. We would like to share a case of giant cell tumor of bone arising from the left orbital roof with involving ethmoid sinus, which was diagnosed to be a meningioma before surgery.
Case description: A 32-year-old lady presented to us with the chief complain of left proptosis, diplopia, and left eye soreness without decline of visual acuity for about 2 months. Her orbital magnetic resonance imaging (MRI) disclosed a mass lesion located in the left frontal base, orbital roof, and upper medial orbital region with adjacent dural-tail sign favoring meningioma. She underwent a left supraorbital pterional craniotomy with the gross total removal of tumor and dura reconstruction. Histology examination of the tumor showed a picture of giant cell tumor of bone. Considering giant cell tumor of bone is locally aggressive, postoperative adjuvant therapy with Denosumab was introduced after full explanation.
Conclusion: Standard treatments of skull-base giant cell tumors have yet to be established due to small number of cases reported in the literature. The standard treatment of giant cell tumor of bone is complete resection of the tumor.
Keywords: Anti-RANKL monoclonal antibody; giant cell tumor of bone; orbital roof tumor.