PET/CT imaging of giant primary pulmonary meningioma: a case report and literature review

Abstract

Background An ectopic meningioma, such as a primary pulmonary meningioma (PPM), is a rare type of tumor that primarily originates outside of the central nervous system. The most common presentation of PPM is isolated pulmonary nodules or masses, and most of them are benign. Only sporadic cases have been reported. This case reported a giant primary pulmonary meningioma and systematically reviewed previously reported cases in the literature. Case presentation A 55-year-old female suffered from asthma after activity, chest tightness, and a persistent dry cough for 2 months. Chest computed tomography (CT) showed a huge mass with calcification in the left lower lobe. And positron emission tomography (PET)/CT revealed mild FDG accumulation of the mass. The mass was finally surgically removed and PPM was confirmed according to histopathologic examinations. Conclusion PPM is a rare disease with heterogeneity not only in CT features but also in glucose metabolism. FDG uptake levels do not identify benign from malignant, benign PPM may have high FDG uptake and malignant may have low.

Primary pulmonary meningioma and minute pulmonary meningothelial-like nodules: Rare pulmonary nodular lesions requiring more awareness in clinical practice

“…Meningiomas occurring in tissues and organs not covered by the meninges are termed ectopic meningiomas. PPM is defined as a primary meningioma in the lung tissue[ 3 ] and is classified as a rare condition under the category of lung tumors of ectopic tissues according to the World Health Organization (WHO) Classification of Thoracic Tumors[ 4 ].…”

“…It has also been suggested that a conservative approach, using close medical monitoring, is the best option for patients when the location, size, and number of smaller nodules challenge the accessibility for biopsy or resection[ 13 , 15 ]. Malignant PPMs are prone to recurrence or metastasis, leading to a poor prognosis[ 3 , 16 , 17 ]. Conversely, some reports have indicated that the prognosis of patients with malignant PPM is actually favorable owing to a typically slow progression[ 6 ].…”

“…Although the average diameter of malignant PPMs is larger than that of benign PPMs, it is impossible to diagnose them based solely on tumor size. In one PPM case, the tumor measured 9.5 cm × 8.4 cm × 5.3 cm in size, but pathological examination confirmed it was benign[ 3 ].…”

“…Therefore, the pattern of enhancement may not help determine whether the PPM is benign or malignant[ 7 , 22 , 23 ]. PPMs exhibit anywhere from mild to high metabolic activity, and the average value of SUVmax is 4.36, ranging from 0.6 to 12.9, although this factor has no relevance for malignant evaluation[ 3 ]. A recent study reported increased 18F-FDG uptake in synchronous benign and malignant PPMs[ 23 ].…”

“…However, meningiomas originating from the lungs are even more rare. Although the pathogenesis of PPM and MPMN remains unclear, it is generally believed that ectopic meningioma is derived from pluripotential subpleural mesenchymal cells or heterotopic embryonic rests of arachnoid cells[ 3 ]. Some scholars believe that PPMs originate from MPMNs based on their similar morphological, immunohistochemical and ultrastructural features[ 8 , 34 ].…”