Renal cell carcinoma metastasis to meningioma: A case report

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. Hereby, we present a rare case of renal cell carcinoma (RCC) metastasizing to intracranial meningioma. In order to show the clinical significance of this case, we reviewed all of the previously reported eleven cases of RCC-to-meningioma. 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. 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.