Primary meningiomas of the lung are rare. Most pulmonary meningiomas are typical syncytial or transitional meningiomas with smaller numbers of fibrous-type tumors. Herein, we report an unusual pulmonary tumor with the microscopic, immunohistochemical, and ultrastructural characteristics of a chordoid meningioma. The tumor was composed of cords and fascicles of small- to medium-sized spindle and epithelioid cells with eosinophilic cytoplasm and round nuclei with finely dispersed chromatin. The tumor cells were surrounded by an abundant mucoid, vacuolated stroma. The periphery of the tumor was enveloped by a significant lymphoplasmacytic infiltrate. The neoplastic cells were positive for vimentin and epithelial membrane antigen only. The unusual morphology of the tumor caused significant diagnostic difficulties. The differential diagnosis included inflammatory myofibroblastic tumor, spindle cell myoepithelioma, and extraskeletal myxoid chondrosarcoma. To the best of our knowledge, this is possibly the first description of an extracranial or intrapulmonary chordoid meningioma.
