Primary pulmonary meningioma or large meningothelial-like nodule? A clinicopathological dilemma

Introduction: Primary pulmonary meningiomas (PPMs) are rare ectopic tumors that potentially arise from displaced embryonic arachnoid cells that are isolated outside the dura mater. Its presence outside of the central nervous system poses inherent challenges. We report a case of a primary pulmonary meningioma discovered after a 12-year follow-up for a presumed benign lung lesion. Case Report: A 47-year-old male with a 17-year history of severe, undiagnosed right-sided subxiphoid and periumbilical pain was monitored for a right middle lobe lung mass that grew from 2.2 cm to 3.4 cm over 12 years. Initially, the transthoracic needle biopsy suggested a solitary fibrous tumor. Video-assisted thoracoscopic wedge resection with concomitant biopsy displayed the characteristic histomorphology, including whorling and psammomatous calcification. Positive immunohistochemical staining for epithelial membrane antigen (EMA) and progesterone receptor (PR) supported the diagnosis of clinically confirmed PPM. Conclusion: This interesting case illustrates that primary pulmonary meningiomas can mimic other tumors and may be associated with atypical symptoms like chronic pain. In this 12-year monitored case, surgery relieved the patient’s debilitating 17-year-long chronic pain. Additionally, a novel nomenclature system was developed to help distinguish between PPMs and large meningothelial-like nodules.