Case report of large solitary skull base metastasis from renal cell carcinoma as initial clinical presentation: Radiological findings and differentials.

A 58-year-old male with good past health presented with headache and visual disturbance for 1 month. Computed tomography (CT) and magnetic resonance imaging (MRI) were performed, showing a large aggressive midline mass with epicenter at the skull base and sellar-suprasellar region. There was marked heterogenous enhancement and intratumoral calcifications. It demonstrated clivus erosion, sphenoid sinus invasion, cavernous sinus invasion and optic chiasm compression. The imaging features were considered to be consistent with clival chordoma and the patent underwent emergent endoscopic transsphenoidal surgical excision. The difficult operation found an unexpected highly vascularized tumor and histopathology of the excision showed clear cell renal cell carcinoma metastasis. Subsequent work up of the patient with positron emission tomography-computed tomography (PET-CT) confirmed suspicion of the primary tumor, arising from left kidney. This case demonstrates an underestimated differential diagnosis of a large aggressive skull base mass as the first initial clinical presentation of metastatic disease.