Treatment with Denosumab in Clival Giant Cell Tumor: Imaging Finding

Introduction: Giant cell tumor is an aggressive, osteolytic, stromal osteoclastogenic (Xu, 2013). It represents 3 to 7% of every bone tumor (Goto, 2017). It occurs in adulthood, between 20 and 40 years (Bardakchyan, 2017; Zhang, 2013), with a male:female ratio of 1:1, 2 to 1:1, 1, 5 (Xu, 2013). Cranial location is infrequent, <  1% of all giant cell tumors. Clival presentation is even more rare, with just 10 published cases (Shibao, 2015).

Case Presentation: A 17-year-old female patient with 1-year history of evolution of diplopia, left hypoesthesia in V1 and V2 territory, left abducens paresis, and left ear hearing loss. Magnetic resonance (MR) showed expansive process in clivus.

Transnasal endoscopic tumor exeresis was performed, achieving a subtotal wide resection of the intrasphenoidal expansive process, leaving a probable remnant in the left cavernous sinus.

Deferred biopsy was compatible with giant cell tumor: proliferation of mononuclear cells, interspersed with giant cells multinucleated osteoclast type.

Two months postoperatively, the patient developed with increased symptoms, seizures, left nystagmus, and left faciobrachial crural hemiplegia. Computed tomography (CT) and MRI showed a large expansive process dependent on the clivus of greater volume that compressed the trunk. The second subtotal transnasal endoscopic tumor exeresis was performed, due to the high risk of bleeding from the basilar territory. During the postoperative period, the patient evolved favorably, decreasing his symptoms. Chemotherapeutic treatment with RANK-L inhibitor was indicated.

Conclusion: The expansion of the tumor after a subtotal resection can be evidenced in MRI after a couple of weeks postoperatively (Goto, 2017). However, after completing the first cycles of treatment with denosumab, in addition to confirming the regression or nonprogression of tumor growth in MRI (Goto, 2017), it is possible to find a lower signal in T2 with respect to the pretreatment image, which would result in tumor fibrosis (Hakozaki, 2014) or the formation of bone callus as part of the pathological fracture repair process (Zhang, 2013). In T1 sequence with contrast, areas of central hypodensity, suggestive of focal necrosis, could be identified (Bardakhchyan, 2017).

More evidence is needed to support the administration of denosumab and long-term follow-up of patients. MRI is a useful tool in the diagnosis and monitoring of GCT. It is still necessary to establish a standard imaging standard.