Rare Tumor-to-Tumor Metastases Involving Lung Adenocarcinoma to Petroclival Meningiomas.

Background: Lung carcinoma metastasizing to a skull base meningioma remains an extremely rare phenomenon, with only 3 studies reported. Furthermore, no documented cases have been reported in the petroclival region. Thus, we have presented the first 2 cases of tumor-to-tumor metastasis (TTM) in which a petroclival lesion, initially thought to be purely meningioma, was also found to contain metastatic lung adenocarcinoma.

Case Description: We present the cases of 2 patients with a known history of lung adenocarcinoma and stable petroclival meningioma who had presented with new-onset neurologic deficits. Repeat imaging studies for both patients found an increased lesion size and peritumoral enhancement; thus, both patients underwent emergent craniotomy for complete lesion resection. Intraoperatively, both lesions had zones of markedly different tumoral texture. On histologic analysis, both lesions showed metastatic lung adenocarcinoma contained within the primary petroclival meningioma.

Conclusion: Skull base TTM is a rare entity for which no specific management guidelines have been created. Therefore, even if the imaging characteristics suggest a more benign process, skull base TTM should remain high on the differential diagnosis for patients with a known primary cancer and new-onset, rapidly progressive, neurologic deficits. Close clinical follow-up with short-interval repeat imaging in this subset of patients might prevent misdiagnosis and facilitate prompt treatment.