Unusual Alliance: Renal Cell Carcinoma Metastasis Coalesces with Meningioma – A Unique Case Study

Introduction: The occurrence of tumor-tumor metastasis (TTM) - the spread of one tumor to another - is extremely uncommon in clinical practice. In tumour-tumour metastasis (TTM), a main tumour functions as the recipient tumour, while a different tumour functions as the donor tumour. Meningioma is the most frequent benign tumour to house a metastasizing malignancy, making up 36% of intracranial tumours. Case report: The patient is a 75-year-old male who presented with 5 episodes of GTCS associated with difficulty in walking. There is no history of headache and vomiting. MRI brain showed right frontal SOL, and an FDG PET CT scan showed it as a metabolically active solid-cystic hemorrhagic lesion. Microscopy revealed a neoplasm with two distinct histological components composed of nests and sheets of cells with vesicular nuclei and clear cytoplasm on the one hand and a whorled tumour with nuclear pseudo inclusions on the other. On Immunohistochemistry, the neoplastic clear cells were positive for CK, CD10, CA-9, Vimentin, and AMACR revealing its renal origin. Discussion There are not many instances of tumor-to-meningioma metastases, and there's no set standard of care. Surgical excision appears to be the most common option, occasionally followed by chemotherapy and postoperative radiation. Conclusion Tumor-to-tumor metastasis is an uncommon condition that doctors should be aware of. An original extracranial tumour with a positive history should elevate the possibility of tumour-to-tumour spread.