Renal cell carcinoma metastasis to meningioma: A case report

Background: Meningiomas are the most common primary intracranial tumors that account for about 35% of all brain tumors. Tumor-to-tumor metastasis (TTM) refers to a rare phenomenon in which a malignant tumor metastasizes to another tumor of totally different origin.Material and Methods: Hereby, we present a rare case of renal cell carcinoma (RCC) metastasizing to intracranial meningioma. In order to show the clinical sig-nificance of this case, we reviewed all of the previously reported eleven cases of RCC-to-meningioma.Case description: A 79-year-old female patient previously diagnosed with RCC was referred to our department for a progressive right hemiparesis and personality change. Computed tomography and magnetic resonance imaging showed left frontal heterogeneously-enhancing extra-axial mass. Image findings gave a suspicion of an atypical meningioma or hemangiopericytoma. Considering the history of a known primary, brain metastasis was a possible differential diagnosis. Histological examination revealed the mass was composed of two different types of tumors co-existing at the same time. A metastatic renal cell carcinoma was enwrapped completely by meningioma of meningothelial type, suggesting TTM. Conclusion: TTM is a very rare phenomenon. However, atypical findings of brain images and a history of known extra-cranial tumor could be a clue to include TTM as possible differential diagnosis.