Pulmonary adenocarcinoma⁃to⁃meningioma metastasis with meningeal carcinomatosis

Objective To investigate the clinicopathological features of pulmonary adenocarcinoma ⁃ to ⁃ meningioma metastasis with meningeal carcinomatosis, and to reduce the rate of missed diagnosis of this disease. Methods and Results A 58⁃year⁃old female was admitted to hospital due to repeated headaches for 4 years and increased dizziness and vomiting for 2 months. Head MRI showed a space ⁃ occupying lesion in left apical petrous cross middle posterior fossa (mainly in the posterior fossa). Microscopy showed the tumor was mainly composed of meningothelial meningioma. In addition, the implantation of adenocarcinoma cells on the surface of arachnoid, and the small tumor adenocarcinoma nests in the meningioma were found. The cerebrospinal fluid cytology found heterotypic tumor cells. Immunohistochemical staining showed meningioma components expressed progesterone receptor (PR), somatostatin receptor 2 (SSTR2), Ki ⁃ 67 proliferation index was 3% ; adenocarcinoma components express cytokeratin (CK), cytokeratin 7 (CK7),