We report a case of a collision tumor, a meningioma complicated with metastasis from a primary renal cell carcinoma. A 75-year-old man, with known history of renal cell carcinoma, and 10-year history of stable meningioma developed neurological symptoms. Computed tomography and magnetic resonance imaging revealed left frontal intracranial extra-axial mass with imaging criteria suspicious for an atypical meningioma or hemangiopericytoma. Given the history of a known primary, the possibility of brain metastasis was included. Pathology confirmed the presence of metastatic renal cell carcinoma nidus with a surrounding meningioma. Tumor-to-tumor metastasis or collision tumor is a very rare phenomenon. Atypical radiologic findings with positive history of a primary extracranial tumor should raise the suspicion of potential metastases.
Keywords: CBTRUS, Central Brain Tumor Registry of the United States; CT, Computed tomography; Collision tumor; Meningioma; RCC, Renal cell carcinoma; Renal cell carcinoma; Tumor to tumor metastasis; WHO, World Health Organization.
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