Giant Renal Cell Carcinoma Metastasis to the Skull Base with Temporal Bone Invasion: A Case Report and Review of the Literature

Objectives: To review the incidence, clinical presentation, and management of metastatic renal cell carcinoma to the lateral skull base and temporal bone, and describe a case of giant clear cell renal cell carcinoma metastasis to the skull base with temporal bone invasion.

Study Design: Case report and literature review.

Methods: The case of a patient with ear fullness, ultimately found to have metastatic renal cell carcinoma involving the posterior fossa and temporal bone, is reviewed. The clinical, radiologic, and pathologic features of the disease are discussed, with description of a transtemporal approach to the posterior fossa and mastoidectomy for surgical resection.

Results: A 67-year-old female presented to a tertiary center with recent onset decreased hearing, ear fullness, and intermittent pulsatile tinnitus on the left side. Magnetic resonance imaging revealed a 6 × 5 × 4 cm posterior fossa mass with central necrosis and contrast enhancement on T1-weighted imaging (Figs. 1, 2). The mass eroded calvarial bone with extension into the retroauricular subgaleal tissue. It also eroded the posterior fossa plate with extension into the mastoid. Cranial nerve function was grossly intact. The patient had a history of renal cell carcinoma with lung and liver metastases in 2015. She underwent nephrectomy and immunotherapy until 2018, with stable hepatic and lung lesions at that time. Given this history, metastatic disease was suspected. Surgical resection via retroauricular approach to the posterior fossa with mastoidectomy was performed after preoperative embolization. Gross total resection was achieved (Fig. 3). Postoperatively, the patient was neurologically intact with no cranial nerve deficits. Pathology revealed metastatic clear cell renal cell carcinoma (Fig. 4). The patient is currently undergoing adjuvant radiation and immunotherapy.

Conclusions: Metastatic renal cell carcinoma to the temporal bone is a rare condition with few reported cases in the literature. Surgical resection with adjuvant radiation therapy is favored for large tumors. Close posttreatment surveillance is required given the aggressive nature of this tumor.

Fig. 1. Preoperative axial magnetic resonance imaging demonstrating a giant left-sided extra-axial mass with bony destruction. The mass measured 6 × 5 × 4 cm in dimension with displacement of the adjacent brain parenchyma.

Fig. 2 Preoperative coronal magnetic resonance imaging demonstrating a giant left-sided extra-axial mass with bony destruction. The mass measured 6 × 5 × 4 cm in dimension with displacement of the adjacent brain parenchyma.

Fig. 3 Postoperative magnetic resonance imaging demonstrating gross total resection of metastatic renal cell carcinoma. Postsurgical changes are seen from left mastoidectomy and left occipital craniectomy with mass lesion resection.

Fig. 4 Surgical pathology demonstrating metastatic clear cell renal cell carcinoma. 4× magnified view of nested pattern of tumor cells with clear cytoplasm, delicate yet distinct cell borders, with net-like array of delicate capillaries dividing cells into individual nests.