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Radiol Case Rep
Radiol Case Rep
Radiology Case Reports
1930-0433
Elsevier

S1930-0433(24)00752-0
10.1016/j.radcr.2024.07.169
Case Report
Case report of large solitary skull base metastasis from renal cell carcinoma as initial clinical presentation: Radiological findings and differentials
Cheung Ivan Hoi Wei MBBS, BEng, FRCR dr.ivan.cheung@gmail.com
a⁎
Mahboobani Neeraj Ramesh MBBS, FRCR, FHKCR, FHKAM b
Poon Wai Lun MBBS, FRCR, FHKCR, FHKAM b
a Department of Radiology, Queen Mary Hospital, Hong Kong Island, Hong Kong SAR
b Department of Diagnostic and Interventional Radiology, Queen Elizabeth Hospital, Kowloon, Hong Kong SAR
⁎ Corresponding author. dr.ivan.cheung@gmail.com
30 8 2024
11 2024
30 8 2024
19 11 53765379
13 6 2024
28 7 2024
29 7 2024
© 2024 The Authors. Published by Elsevier Inc. on behalf of University of Washington.
2024

https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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.

Keywords

Skull base metastasis
Renal cell carcinoma metastasis
Midline sellar-suprasellar mass
Chordoma
Chondrosarcoma
Invasive pituitary adenoma
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pmcIntroduction

A large midline skull base and sellar-suprasellar mass with aggressive appearance and bone destruction would construct a wide number of differentials. It would be reasonable to consider differentials of chordoma, chondrosarcoma, invasive pituitary macroadenoma, plasmacytoma / multiple myeloma and metastasis.

However metastasis is often not ranked as high when there is no history of carcinoma. A background of known primary carcinoma elsewhere in the body may raise this index of suspicious but it remains a rare first presentation as a solitary skull base or sellar-suprasellar lesion.

When skull base and sellar-suprasellar masses are large, their origin can be difficult to delineate and tend to involve multiple adjacent structures including paranasal sinus, cavernous sinus, optic chiasm and vascular encasement. Imaging features of the above differentials can overlap, and this case report intends to highlight the radiological features that were mimicked in this case of skull base metastasis.

Case report

A 58-year-old male with no significant past medical history presented with worsening headache and visual disturbance for 1 month. Clinical examination revealed reduced visual acuity of both eyes, reduced visual field in the right eye and relative afferent pupillary defect in the left eye. The patient was fully conscious with no other neurological deficit.

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 measuring up to ∼3.6 × 4.5 cm in axial span. CT demonstrated bony destruction of sellar turcica, dorsum sellae, anterior clivus, sphenoid sinus and posterior ethmoid sinus. There was presence of intratumoral coarse calcifications. See Fig. 1.Fig. 1 Computed tomography images of the brain in axial, sagittal and coronal views in soft tissue window (A-C) and in bone window (C-E). Shows large aggressive midline sellar-suprasellar soft tissue mass with extensive skull base bone destruction, paranasal sinus destruction, bilateral cavernous sinus invasion and intratumoral calcification.

Fig 1

MRI demonstrated a soft tissue mass with mixed hyperintense and hypointense T1W signal, heterogeneously hyperintense T2W signal and heterogeneous contrast enhancement. Few small internal areas of restricted diffusion were seen. Suprasellar extension resulted in compression and splaying of optic chiasm. Inferiorly, the floor of the pituitary fossa was eroded with expansion, and the tumor extended into the sphenoid and ethmoid sinuses. The anterior clivus was invaded by tumor as seen on CT. Laterally, there is evidence of bilateral cavernous sinus invasion and significant circumferential encasement of bilateral cavernous internal carotid artery segments. Posteriorly there is bulging into the prepontine cistern. Normal pituitary gland tissue could not be identified. See Fig. 2.Fig. 2 Magnetic resonance imaging of the brain. (A) Axial T2W sequence; (B) Axial T1W sequence; (C) Axial T1W sequence with contrast; (D) Sagittal T1W sequence with contrast and fat-suppression; (E) Coronal T1W sequence with contrast and fat-suppression; (F) Coronal fluid attenuated inversion recovery (FLAIR) sequence. Shows lobulated expansile midline skull base and sellar-suprasellar region mass demonstrating marked hyperintense T2W signal and marked heterogeneous contrast enhancement.

Fig 2

Combining the patient history and first presentation, the working diagnosis was clival chordoma with differentials being chondrosarcoma and invasive pituitary macroadenoma.

The patient underwent emergent endoscopic transsphenoidal surgical excision given the large mass effect. The difficult operation found an unsuspecting highly vascularized tumor and gross total resection was performed with significant intra-operative hemorrhage encountered. Histopathology of the excision showed clear cell renal cell carcinoma (RCC) metastasis. Subsequent work up of the patient with positron emission tomography—computed tomography (PET-CT) confirmed the suspicion of renal primary and was found in the left kidney lower pole with renal vein invasion. Further metastasis to left clavicle was also found.

Postoperative ophthalmological assessment showed improved visual acuity. The patient is now being managed by oncology colleagues.

Discussion

A large midline aggressive mass involving the skull base and sellar-suprasellar region with extensive bony destruction, particularly the clivus, would commonly raise differentials including chordoma, chondrosarcoma, invasive pituitary macroadenoma, plasmacytoma / multiple myeloma, and metastasis.

However solitary metastasis to this region is a relatively rare entity and often overlooked as a result. A literature review showed breast, prostate, lymphoma and lung carcinoma secondaries to the skull base were the most frequent in this subset of skull metastasis, which can occur in 4% of cancer patients [1]. The most common primary cancer affecting the sellar region were lung and breast, followed by renal according to a literature review study [2].

Clival chordoma is a primary bone tumor with aggressive local invasion. They are considered midline lesions with expansile appearance and intratumoral fragmented calcifications. They are T1W hypointense / intermediate signal, T2W hyperintense and show marked heterogenous contrast enhancement.

Skull base chondrosarcoma share similar characteristics of chordoma but tend to be off-midline and centered at the petro-occipital fissure. They demonstrate calcifications of arcs and rings configuration. The MRI imaging pattern is similar to chordoma but usually have higher ADC values.

Invasive pituitary adenomas arise from the sellar and invades locally with propensity for more inferior than superior growth, causing sellar expansion and extension to cavernous sinus, sphenoid sinus and clival erosion. Usually there are no associated intratumoral calcification and the normal pituitary gland cannot be identified. Variable T1W/T2W signal is seen with intense heterogenous enhancement.

Plasmacytoma / multiple myeloma are the most common adult primary malignant bone neoplasm. They are hyperdense and show lytic destruction with nonsclerotic margins. They are also expansile and can have areas of preserved thinned cortical bone. Usually homogenously enhancement is demonstrated. Commonly T1W/T2W isointense though can be T1W hypointense and T2W hyperintense.

The imaging findings of skull base metastases are more heterogenous and less specific, however multiple skull lesions should alert this differential. CT can show lytic or sclerotic destruction. On MRI they are usually T1W and T2W iso/hypointense and replace marrow fat signal, and there is variable homogenous or heterogenous contrast enhancement [3]. A history of known primary neoplasm should also raise index of suspicion, but in this case the primary tumor was only found afterwards.

In this case report, the large RCC metastasis demonstrated multiple mimicking features of chordoma, including lobulated expansile appearance, aggressive bone destruction, intra-tumoral calcifications, hyperintense T2W signal and marked heterogeneous contrast enhancement. It highlights there can be difficulty in diagnosing large aggressive skull base or sellar-suprasellar masses. This publication serves to demonstrate the radiological appearance of another case and contribute to the limited literature.

Conclusion

This case report intends to highlight the importance of considering solitary metastasis as a differential diagnosis for patients presenting with radiological features of aggressive midline skull base or sellar-suprasellar mass.

Patient consent

The authors confirm appropriate patient consent form has been obtained for medical journal publication and available upon request.

Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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