Tumor-to-Tumor Metastasis of Multiple Meningiomas and Clear Cell Renal Cell Carcinoma Metastasis as First Clinical Appearance of Kidney Cancer: A Case Report and Analysis.

Background  Meningioma accounts for more than 35% of all diagnosed brain tumors of the central nervous system and, moreover, it is the most common benign recipient of tumor-to-tumor metastasis. Several cases with tumor-to-meningioma metastasis by breast, lung, and intestinal cancer have been described before. Case description  The case of a patient with a longstanding history of multiple meningiomas ( n  = 4) that suddenly became symptomatic and progressive in size is presented. Following extirpation of the two largest meningiomas, a histological examination revealed two separate tumor-to-meningioma metastases of clear cell renal cell carcinoma that was undiagnosed before. Post-surgical computed tomography scan then confirmed tumor-suspect lesions in both kidneys. After recovery and rehabilitation, adjuvant radio-chemo-therapy was applied according to protocols for kidney cancer. No other tumor-to-tumor-suspect event occurred since then for the remaining two meningiomas. Conclusion  Review of literature and our case strengthens the idea of meningioma as a favorable premetastatic niche. Considering that the patient lived with a stable disease for many years, a sudden progress of tumor size in association with neurological deterioration was highly suspected for malign involvement, including the possibility of tumor-to-tumor metastasis. Physicians should be aware about this phenomenon and treat patients accordingly to the underlying disease.