Primary Pulmonary Malignant Meningioma: A Case Report and Literature Review Focusing on Imaging Findings

Background Primary pulmonary meningioma (PPM) is an extremely rare primary tumor of the lung. The diagnosis should first exclude metastasis of central nervous system MPM by using imaging, and the final diagnosis depends mainly on the tissue pathology and immunohistochemical results. Malignant PPM is even rarer, and a clear pathological definition to distinguish between benign and malignant PPM is lacking.Case Presentation A 47-year-old woman was admitted to the hospital after a lung mass was found during a physical examination one month earlier. The imaging findings for this patient showed a large mass in the lower lobe of the left lung with bronchial invasion. A contrast-enhanced MRI of the brain was normal. Bronchoscopy shows a mass at the opening of the left lower basal branch, with mucosal infiltration, protrusion, and stenosis of the opening. The patient underwent radical left lung cancer surgery, and the pathology specimens stained with hematoxylin-eosin demonstrated tumor cells with the focal invasion of the bronchial cartilage. Immunohistochemical staining was positive for epithelial membrane antigen(EMA), somatostatin receptor 2 (SSTR2), progesterone receptor (PR), Ki-67 (5%-10%), CD34, and D2-40 and weakly positive for p53.The pathologic diagnosis was primary pulmonary meningioma (PPM). The tumor marker CA-125 had significantly increased in the 2 months after surgery.Conclusion Malignant PPM is rarer, and a clear pathological definition to distinguish between benign and malignant PPM is lacking. Potential cases should be comprehensively evaluated based on imaging, laboratory, and pathology results. A long-term regular follow-up will be required to rule out metastasis or recurrence of PPM.