Primary Pulmonary Meningiomas: Report of Two Cases and Review of the Literature

Background: Meningiomas rarely occur outside the skull, and primary pulmonary meningiomas (PPMs) are more rare. Only a few cases have been reported in the literature. The clinicopathological characteristics are not clear and it is easy to be misdiagnosed, so it is very important to master its diagnosis and differential diagnosis.

Methods: We report two women with primary pulmonary meningioma. At the time of physical examination, the small solitary pulmonary nodules were detected on chest radiograph, and wedge resection was performed by Video-assisted Thoracoscope Surgery(VATS), and histologic evaluation showed that the lesions were benign PPMs. The clinicopathological features, immunophenotype and differential diagnosis of PPMs were analyzed, with a review of the cases published in the literature.

Results: The study group comprised of 40 patients, 14 males and 26 females. The median age was 56.5 years (range 18-108). Thirty patients who underwent routine screening studies were asymptomatic but had a pulmonary nodule detected on chest X-ray. Nine patients had respiratory symptoms. Only 1 patient had non-specific symptoms. Most of the PPMs were benign, only 3 cases were malignant. Benign PPMs ranged from 0.6 cm to 6 cm in diameter (median 2 cm). The 3 malignant PPMs were 5 cm, 6.5 cm and 15 cm in diameter. The prognosis of benign PPM resection is good, with almost no recurrence or metastasis. But the two of three malignant PPMs relapsed.

Conclusions: PPM is very rare. It needs to be diagnosed by combining histology and immunohistochemistry. Diseases that need to be identified include spindle cell mesothelioma, spindle cell thymoma, spindle cell carcinoma, metastatic tumor, etc.