Intracranial Meningioma as Initial Clinical Manifestation of Occult Lung Carcinoma: Case Report

Intracranial meningioma with intratumor metastasis have been occasionally reported. However, to our knowledge, there are almost no reports of malignant tumors initially discovered due to metastasis to meningioma. A 74-year-old woman presented with amnesia. Magnetic resonance imaging showed a well-defined mass arising from falcotentorial junction and homogeneous enhancement. Histopathologic findings showed that the mass was a meningothelial meningioma, with the majority of the tumor cells propagating in sheets, however, a single area in the tumor tissue showed the different histology. Immunohistologically, cytokeratin 7 (CK7), thyroid transcription factor-1 (TTF-1), and Napsin were positive, which led to lung adenocarcinoma metastasis. Furthermore, E-cadherin staining showed a 70% positive rate in lung adenocarcinoma and 30% in meningothelial meningioma. We report our experiences regarding a case of lung cancer that metastasized to intracranial meningioma and its clinical presentation and pathology.