Easily misdiagnosed metaplastic meningioma: one case report and review of literature

Objective Metaplastic meningioma is rare lesion which is very difficult to diagnose clinically, and is easy to be misdiagnosed. This article aims to reveal the clinical manifestations and histopathological features of this disease. Methods One case of ossification metaplastic meningioma was reported and the relevant literatures were reviewed. Results A 17-year-old female patient showed paroxysmal stiffness accompanied by convulsion of extremities, headache, vomiting and fever. Cranial CT scan demonstrated an irregular low-density signal in the right frontal and parietal lobes. The lesion did not have a clear boundary, and there was a calcificated high-density signal inside it. The size of the lesion was about 2 cm × 1.80 cm × 1.70 cm. Cranial MRI scan showed a tumor with size of 2.40 cm × 2.10 cm × 2 cm, located in the right frontal and parietal lobes, and there was large edema around the lesion. A resection was performed, and a lesion was found in the right frontal and parietal parenchyma, whose one side was close to the cerebral pia mater and did not invade into the dura and the skull. The tumor was yellow, in irregular shape, and had clear boundary, with hard texture and rich blood supply. Its size was about 3 cm × 2.50 cm × 2 cm. There was extensive ossification and calcification within the tumor under microscope. Tumor cells were flaky and like small nests, which were distributed in the mesh?like arranged trabecular bone. The immunohistochemical staining showed that epithelial membrane antigen (EMA), progesterone receptor (PR), vimentin (Vim) and Bcl-2 were positive for tumor cells with Ki-67 labeling index being about 6%. Conclusions Metaplastic meningioma has various metaplastic components and its imaging features are also various. However, it could be diagnosed and identified from other similar tumors by histopathological observation and immunohistochemical staining. doi: 10.3969/j.issn.1672-6731.2014.08.010