Abstract Metastatic tumors account for a small proportion of cerebellopontine angle (CPA) lesions, which are predominantly benign. Renal cell carcinoma (RCC) metastases to the brain are fairly common but rarely involve the CPA. Presentation of metastatic RCC initially as a CPA mass without prior diagnosis of the primary in kidney is exceptionally uncommon. A 40-year-old man presented with headache, right-sided facial numbness, and cerebellar signs. Magnetic resonance imaging demonstrated a well-defined, homogeneously enhancing extra-axial mass in the right CPA with a broad-based dural attachment and dural tail, which was suggestive of meningioma. Patchy blooming was noted on susceptibility-weighted imaging indicating hemorrhagic components. Retrosigmoid craniotomy was performed, however, marked intraoperative hypervascularity limited safe resection, and a biopsy was obtained. Histopathology and immunohistochemistry (CK, PAX-8, CA-IX, CD-10 positive) confirmed metastatic clear cell RCC. Subsequent abdominal imaging revealed a previously undiagnosed renal mass. The patient remains neurologically stable at 1-month follow-up and is undergoing radiotherapy, with nephrectomy planned. RCC metastasis to the CPA may radiologically mimic meningioma. The presence of hemorrhagic components and pronounced hypervascularity should raise suspicion for metastatic disease, even in the absence of known primary malignancy. Preoperative systemic evaluation may be considered in atypical hypervascular CPA lesions.
Kuriyal et al. (Mon,) studied this question.