Abstract Introduction Meningiomas are the most common primary central nervous system (CNS) tumors and are predominantly benign. Only 0.1-1% metastasize, most frequently to the lungs 1. Pulmonary spread from World Health Organization (WHO) Grade 1 meningiomas is exceedingly rare 2. We report an incidental detection of metastatic pulmonary meningioma during routine breast cancer screening in a middle-aged woman. Case Presentation A 49-year-old woman with a history of recurrent WHO Grade 1 extra-axial cervicothoracic meningiomas, status post surgical resection and adjuvant radiation therapy in 2008 and 2013, underwent screening mammography. The mammogram revealed dense breast tissue, prompting further evaluation with breast magnetic resonance imaging (MRI). Incidentally, two pulmonary nodules and dural enhancement at the T4 vertebral level were identified. A subsequent whole-body positron emission tomography/computed tomography (PET/CT) scan demonstrated two small hypermetabolic pleural-based nodules with central calcification, along with hypermetabolic uptake within the dorsal spinal canal at the T4 level. The patient underwent navigational bronchoscopy with transbronchial forceps and cryo-biopsy of the pleural based nodule. The procedure was complicated by a pneumothorax, which was managed with chest tube insertion. Histopathologic examination of the nodule revealed tumor cells with abundant eosinophilic cytoplasm, round-to-oval nuclei with prominent nucleoli, and psammomatous calcifications in the background. Mitotic activity was low (4 mitoses per 10 high-power fields). Immunohistochemical staining was positive for SSTR2a and EMA, with weak nuclear progesterone receptor (PR) expression. The Ki-67 proliferation index was 5%. These findings were consistent with a WHO Grade 1 meningioma. Magnetic resonance imaging of the brain revealed no evidence of intracranial meningioma. The patient is currently under the care of hematology-oncology for targeted therapy based on next-generation sequencing results, with no surgical intervention planned given the metastatic nature of the disease. Discussion Although meningiomas rarely metastasize, the lungs remain the most common site of spread. Metastases typically occur in higher-grade subtypes; thus, pulmonary dissemination from a Grade 1 lesion is exceptional 2,3. This case is notable for the patient’s long-term stability after complete resection and radiation in 2013, followed by several years of negative imaging and an asymptomatic interval before recurrence. The uncertain timing of dissemination underscores the indolent yet unpredictable biology of meningiomas. Conclusion This case emphasizes the need for prolonged vigilance in patients with low-grade meningiomas, as late and distant metastases, though rare, can occur even years after initial disease control. This abstract is funded by: None
Kumari et al. (Fri,) studied this question.