DIAGNOSIS Metastatic clear-cell type of renal carcinoma in a meningothelial meningioma.
He had an uneventful post-operative period. The postoperative evaluation was completed with a body CT-scan, which revealed a mass-lesion in the right kidney and two nodules in the right lung. He underwent whole brain radiotherapy, right radical nephrectomy and adjuvant chemotherapy. The patient was neurological symptom-free on follow-up after 3 months.
Tumor to tumor metastasis is a rare pathological event. Meningiomas have been found to be the most common intracranial tumor to host a metastatic neoplasia. Among these, breast followed by lung carcinoma were the most common primary sites (1). Several theories and biological factors (metabolic, hemodynamic, hormonal, immunological and molecular) have been advanced concerning the genesis of this unusual event (2). Radiologic techniques cannot reliably exclude the presence of metastatic tumor within a meningioma, nor can they establish a definitive diagnosis between meningioma and dural metastasis (10). Both possibilities should be considered in those patients presenting with a solitary intracranial lesion suggestive of meningioma whether or not they harbor an extracranial primary tumor at the same time.
Brain metastases in renal cell carcinoma are not rare events, although it is very rare from a renal cell carcinoma staged T1-2 without systemic metastases. Both metastases in advanced staging cases and isolated metastasis discovered some years after nephrectomy have been reported (7). Only a few cases of renal cell carcinoma metastasizing to an intracranial meningioma have been reported (3, 5, 6, 8, 9). In those cases, a primary renal tumor was known before the neurosurgical procedure. Our case is the first reported metastatic renal cell carcinoma within a meningothelial meningioma without previous knowledge of the existence of the primary malignant tumor.
Therefore, this case could be considered unique: tumor-to tumor metastasis as the clinical onset of an extracranial neoplasia. Due to the overlapping in clinical presentation and despite advances in imaging, pathological examination is still required for its correct diagnosis. In such cases it is imperative to exclude the occurrence of collision between tumors. In order to assess a true metastasis in the tumor, criteria suggested by Campbell et al. could be used (10).
Contributed by Julio César Gutiérrez Morales, MD, PhD, Sandra Eugenia Gutiérrez Morales, Biol. Sci., and Aurora Astudillo González, MD,PhD