A Rare Recurrent Intracranial Meningioma with Variable Histopathological Grades and Pulmonary Metastasis: A Case Report

Summary

Long-term follow-up of recurrent meningioma with dynamic pathological grade changes and rare pulmonary metastasis is valuable for guiding clinical diagnosis and treatment strategies. This patient underwent multiple craniotomies, Gamma Knife therapy, and lung radiofrequency ablation, with an 18-year follow-up period, providing clinical experience for the comprehensive management of meningioma.

Abstract

Meningiomas are predominantly benign intracranial neoplasms, with extracranial distant metastasis occurring in fewer than 1% of all patients; pulmonary metastasis represents an exceedingly rare complication of meningioma progression and recurrence. We describe a 44-year-old male patient with sequentially recurrent intracranial meningioma exhibiting dynamic histopathological grade evolution combined with synchronous bilateral pulmonary metastatic lesions, followed for an unprecedented 18 clinical years. Across follow-up, the patient received four open craniotomies, two sessions of stereotactic Gamma Knife radiosurgery, a CT-guided percutaneous lung biopsy, and minimally invasive pulmonary radiofrequency ablation. Post-intervention serial neurological and radiological monitoring documented favorable functional recovery: final Glasgow Coma Scale (GCS) = 15 and Modified Rankin Scale (mRS) = 1 at latest follow-up, with complete resolution of initial left lower limb weakness and stable control of both intracranial residual sinus-associated tumor and all pulmonary metastatic nodules without newly emerging systemic metastasis. This long-duration real-world clinical cohort highlights the critical necessity of full-body systemic imaging screening and lifelong standardized periodic surveillance for meningiomas with superior sagittal sinus invasion and progressive pathological upgrading, to facilitate early identification of occult distant pulmonary metastasis and formulate individualized combined surgical-radiation-ablation treatment regimens for high-risk recurrent meningioma.

Introduction

Meningioma, derived from arachnoid epithelial cells, is the second most common intracranial tumor, accounting for 20%–30% of intracranial neoplasms¹. Most are benign (World Health Organization, WHO grade 1), while atypical (grade 2) and anaplastic (grade 3) subtypes account for 2%–10%². It predominantly affects adults over 45 years of age and is rare in children³. According to the 2021 WHO classification, meningiomas are graded from 1–3 based on histopathological features, with increasing aggressiveness^4,5. Tumors commonly occur at the cerebral convexity and falx cerebri, rarely in the cerebral ventricles or epidural space⁶.

Distant metastasis of meningioma is uncommon, with an overall incidence < 1%; the rate rises to 2% for grade 2 and nearly 9% for grade 3 tumors, with the lungs, liver, lymph nodes, and bones being frequent metastatic sites^7,8. Primary intracranial meningioma with pulmonary metastasis is rarely reported in clinical practice. This paper reports a case of multiple recurrent intracranial meningiomas with dynamic changes in pathological grade and pulmonary metastasis, which has been followed over 18 years. By summarizing the clinical manifestations, imaging features, pathological characteristics, treatment process, and prognosis of this case, we aim to improve the clinical recognition and comprehensive management level of this rare disease.

Diagnostic and therapeutic challenges persist for metastatic meningioma: occult pulmonary metastatic lesions are usually asymptomatic at the early stage without typical respiratory manifestations such as cough or hemoptysis, leading to missed diagnosis without routine full-body chest imaging; repeated intracranial recurrence coupled with venous sinus infiltration renders gross total surgical resection impossible, and there exists no universally standardized systemic chemotherapy regimen for disseminated meningioma to date. This report details an 18-year sequential recurrent meningioma case featuring progressive pathological upgrading and incidental pulmonary metastasis. By systematically summarizing clinical manifestation, multi-modal imaging characteristics, dynamic pathological evolution, stepwise therapeutic decision-making, and long-term survival prognosis, we aim to upgrade global clinical awareness and standardized comprehensive management of this rare metastatic subtype of meningioma.

Case Presentation
A 44-year-old Han Chinese male was admitted in March 2020 with an 18-year history of recurrent intracranial meningioma and a 2-month history of progressive left lower limb weakness. He had no hypertension, diabetes, smoking history, alcohol abuse, or family history of tumors. The patient underwent his first craniotomy at Beijing Xuanwu Hospital in 2003 for a giant right frontal parafalcine meningioma, and histopathology confirmed papillary anaplastic meningioma (WHO Grade 3). In 2011, he underwent a second craniotomy at Beijing Tiantan Hospital for local tumor recurrence, with pathology demonstrating atypical meningioma (WHO Grade 2). Two sessions of Gamma Knife radiosurgery were subsequently performed in 2013 and 2018 for residual tumor. In 2014, a third craniotomy was carried out for progressive recurrent parasinus meningioma, and pathological examination again confirmed atypical meningioma (WHO Grade 2). Upon the current admission in 2020, the patient underwent a fourth craniotomy for a progressive intracranial mass lesion, achieving Simpson Grade 2 resection. On examination, the patient was fully alert (GCS 15). Left lower limb strength was IV+, right lower limb proximal strength V−, and distal strength IV, graded according to the Medical Research Council (MRC) scale. The left finger-nose test was unsteady, and the gait was ataxic. Enhanced cranial MRI showed an enlarged parieto-occipital parafalcine mass with leftward midline shift. Chest CT demonstrated multiple bilateral pulmonary nodules. CT-guided lung biopsy histopathologically confirmed metastatic meningioma (EMA+, Vim+, Ki-67 ≈1%). Intracranial pathology showed recurrent atypical meningioma. The patient was diagnosed with bilateral parieto-occipital parafalcine meningioma with pulmonary metastasis, moderate anemia, and hypoproteinemia.

Diagnosis, Assessment, and Plan
Diagnosis was based on clinical history, contrast-enhanced cranial MRI, cranial and chest CT, cerebral angiography, histopathology examination, and immunohistochemistry. Intracranial and pulmonary specimens were analyzed to confirm meningioma and exclude primary lung cancer or other metastases.

Differential Diagnoses and Exclusion
The primary differential diagnosis considered was intracranial metastasis from primary lung malignancy. Typical imaging manifestations of lung cancer with intracranial metastasis were not observed on cranial enhanced MRI, which ruled out this possibility. Combined with multidisciplinary consultation by the thoracic surgery team, multiple pulmonary nodules were highly suspected of malignant lesions, requiring further pathological confirmation.

Rationale for Major Diagnostic Investigations
Cranial enhanced MRI was performed to evaluate tumor size, dural adhesion, skull and superior sagittal sinus invasion, as well as midline shift, which guided surgical planning. Chest CT was used for systemic screening to characterize bilateral pulmonary nodules. CT-guided percutaneous lung biopsy was conducted to obtain tissue specimens for histopathological examination, the gold standard to confirm the nature of pulmonary lesions and identify tumor origin.

The final therapeutic regimen included microsurgical resection of recurrent intracranial meningioma to achieve maximal safe resection (Simpson grade 2). For residual tumor within the superior sagittal sinus, combined adjuvant radiotherapy was planned. CT-guided radiofrequency ablation was applied to pulmonary metastatic nodules. Long-term regular neurological assessment and serial imaging surveillance were scheduled postoperatively. Postoperative care consisted of seizure prophylaxis, hemostatic therapy, and nutritional support. Serial cranial MRI and chest CT were arranged to monitor tumor recurrence and distant metastasis dynamically.

Protocol

This single-patient case report was reviewed by the Medical Ethics Committee of Taizhou Municipal Hospital (Approval No. LWSL202500293), which granted an exemption from formal ethical review requirements. Written informed consent for publication of this case report and all accompanying images was obtained from the patient.

1. Preoperative evaluation and clinical data collection

1. Detailed clinical data were collected, including demographics, medical history, neurological symptoms, imaging findings, pathological results, treatment records, and follow-up data. Routine laboratory tests and systemic imaging were performed to evaluate general condition and metastatic status.

2. Imaging examination

1. Cranial enhanced MRI: A 3.0T superconducting MRI scanner was used for routine and enhanced scanning.
2. Cerebral DSA: Evaluated tumor blood supply and venous sinus invasion.
3. Chest enhanced CT: A 64-slice spiral CT scanner was used to detect and locate pulmonary lesions.
4. Chest CT: Patients were positioned supine with arms raised. A 64-slice spiral CT scanner was used for plain scanning to detect the location, number, and size of pulmonary nodules. The largest nodule in the left lower lobe measured approximately 1.8 cm in diameter.

3. CT-guided percutaneous lung biopsy

1. Patient positioning: The patient was placed in a semi-lateral decubitus position on the CT table.
2. Local preparation: After CT localization, the optimal skin puncture site was marked. The skin was disinfected with iodophor, and sterile drapes were applied.
3. Anesthesia: Local anesthesia from the skin to the pleura was administered using 2% lidocaine.
4. Biopsy operation: A biopsy needle was percutaneously inserted into the target pulmonary nodule under real-time CT guidance. Multiple tissue samples were obtained by cutting motion.
5. Post-procedure management: All harvested specimens were sent for histopathological examination. The puncture site was compressed and bandaged to prevent bleeding and pneumothorax.

4. Pathological examination

Surgical specimens were fixed with 4% paraformaldehyde, embedded in paraffin, sectioned, and stained with hematoxylin and eosin (HE). Immunohistochemical staining was performed for EMA, Vimentin, Ki-67, and other indicators to confirm the diagnosis and tumor origin.

5. Craniotomy for recurrent meningioma

1. Patient positioning and anesthesia
   General endotracheal anesthesia was administered. The patient was placed in a left lateral prone position, and the head was fixed with a three-point skull clamp and slightly tilted downward to fully expose the right parieto-occipital region.
2. Surgical approach and incision
   A horseshoe-shaped scalp incision crossing the midline was designed to protect the blood supply of the previous surgical incision. All layers of the scalp were incised, and the musculocutaneous flap was reflected to the left to expose the bilateral parieto-occipital skull. Previous surgical bone flaps, skull holes, and skull locks were visible, with tumor tissue invading the skull. Four additional skull holes were drilled with a high-speed drill, and the bone flap was separated using a milling cutter. The bone flap was carefully removed due to tight adhesion with the dura mater. The final bone window size was approximately 8 cm × 10 cm.
3. Intraoperative tumor resection
   1. A small piece of tumor tissue was sampled for intraoperative frozen section examination, which confirmed meningioma.
   2. The dura mater was suspended, and a stellate incision was made around the tumor. The tumor was tightly adhered to the dura mater and resected piecemeal. The tumor-brain boundary was clear without a complete capsule.
   3. A deep tumor invaded the cerebral falx and extended to the contralateral side. The tumor, together with the involved cerebral falx, was resected completely. Tumor tissue filling the residual superior sagittal sinus was cleared, and the posterior stump of the superior sagittal sinus was repaired surgically. Two cystic cavities adjacent to the falx filled with pale yellow fluid were excised simultaneously.
   4. Resection degree: Maximal safe tumor resection was achieved. The invaded dura mater and cerebral falx were partially excised and cauterized. Tumor residues confined within the superior sagittal sinus were reserved for subsequent radiotherapy, as radical resection would lead to fatal venous hemorrhage.
4. Wound closure
   A suture-free artificial dura mater was used to repair the dural defect. A negative pressure drainage tube was placed under the dura mater. The inner plate of the bone flap invaded by the tumor was polished with a drill. The bone flap was fixed firmly with three sets of titanium connection systems.

6. Gamma knife radiosurgery

Two sessions of Gamma Knife treatment were performed in 2013 and 2018 at an external hospital. Detailed equipment parameters and treatment protocols were not available. This treatment was applied for residual intracranial tumor after surgery.

7. CT-guided pulmonary radiofrequency ablation

Pulmonary radiofrequency ablation for metastatic nodules was conducted at an external hospital. Due to data limitations, detailed lesion selection criteria, operational workflow, and treatment endpoints could not be provided. This minimally invasive therapy was used to control progressive pulmonary metastatic lesions.

8. Postoperative management and long-term follow-up

1. Inpatient postoperative management
   1. Routine hemostatic drugs, anti-inflammatory agents, and antiepileptic prophylaxis were administered after craniotomy. Nutritional support was given to correct preoperative anemia and hypoalbuminemia. Vital signs and neurological function were monitored continuously.
   2. Drainage volume and wound condition were observed closely to prevent intracranial hemorrhage, cerebral edema, and surgical site infection.
2. Long-term follow-up schedule
   Neurological function assessment, cranial MRI, and chest CT were performed every 3–6 months within the first 5 years after the final surgery, and the interval was adjusted to every 6–12 months thereafter for lifelong surveillance, to timely detect intracranial recurrence and new distant metastasis.

Results

The patient completed a total of 18 years of continuous follow-up. Postoperatively, neurological function recovered satisfactorily, with a Glasgow Coma Scale (GCS) score of 15 and a Modified Rankin Scale (mRS) score of 1 at the latest assessment. The patient remained asymptomatic in daily activities, without headache, cerebral edema, or limb dysfunction.

Figure 1 presents the imaging features of the initial tumor and postoperative changes after the first craniotomy: the primary lesion was a large extra-axial meningioma adjacent to the right frontal falx cerebri with superior sagittal sinus invasion; digital subtraction angiography confirmed rich tumor blood supply, and follow-up imaging three years after surgery showed complete tumor resection without local recurrence.

Figure 2 shows imaging and pathological results of the fourth craniotomy. Cranial MRI detected a recurrent tumor invading the superior sagittal sinus, and chest CT revealed multiple bilateral pulmonary nodules suggestive of metastasis. Histopathological staining demonstrated cellular atypia consistent with atypical meningioma (WHO Grade 2). Postoperative imaging confirmed a small residual tumor within the superior sagittal sinus.

Figure 3 documents imaging findings before pulmonary radiofrequency ablation. Multiple falx-based intracranial nodules were observed on cranial MRI. Chest CT clearly localized the dominant metastatic nodule in the left lower lobe, which was selected for CT-guided ablation.

Table 1 summarizes the complete clinical timeline, all surgical and interventional procedures, and dynamic histopathological grades across 18 years of follow-up. The tumor showed dynamic pathological changes from WHO Grade 3 at the first onset to recurrent WHO Grade 2 lesions, and pulmonary lesions were confirmed as WHO Grade 2 metastatic meningioma.

Long-term surveillance confirmed stable control of intracranial residual lesions and pulmonary metastatic nodules. No new distant metastases were detected during the entire follow-up period. Representative imaging and pathological findings are shown in Figure 1, Figure 2, Figure 3, and Table 1.

Figure 1. Cranial imaging and long-term follow-up after the first craniotomy. (A–C) Contrast-enhanced T1-weighted Magnetic Resonance Imaging (MRI) demonstrates an approximately 7 cm intensely enhancing extra-axial mass adjacent to the right frontal falx cerebri, with a broad dural base and prominent meningeal tail sign; the mass invades the superior sagittal sinus. (D) Digital subtraction angiography (DSA) shows a marked tumor blush and hypervascularity supplied by meningeal branches. (E, F) Three-year postoperative contrast-enhanced MRI reveals complete resection with no evidence of local recurrence. Please click here to view a larger version of this figure.

Figure 2. Imaging and histopathology after the fourth craniotomy. (A–B) Contrast-enhanced Magnetic Resonance Imaging (MRI) showing a parieto-occipital mass with invasion of the superior sagittal sinus. (C) Chest CT revealing multiple patchy high-density lesions in both lungs. (D) Hematoxylin and Eosin (HE) staining (×400) showing increased nuclear-to-cytoplasmic ratio, mild-to-moderate cellular atypia, and vascular hyalinization. Scale bar: 50 µm. (E, F) Postoperative MRI at 3 months demonstrating residual tumor within the sagittal sinus. Please click here to view a larger version of this figure.

Figure 3. Imaging during pulmonary radiofrequency ablation. (A–C) Contrast-enhanced MRI showing multiple irregular falx-based nodules with unclear borders adjacent to the superior sagittal sinus. (D) Coronal reformatted chest CT (mediastinal window) confirms multiple bilateral pulmonary nodules; the largest lesion in the left lower lobe demonstrates soft-tissue density, smooth margins, and no cavitation, consistent with metastatic meningioma. (E, F) Axial chest CT (lung window) localizes the target nodule in the anterior basal segment of the left lower lobe, selected for CT-guided radiofrequency ablation. MRI: Magnetic Resonance Imaging; CT: Computed Tomography. Please click here to view a larger version of this figure.

Time Point	Clinical Event	Pathological Diagnosis	WHO Grade
2003	First craniotomy (right frontal parafalcine meningioma)	Papillary meningioma	3
2011	Second craniotomy for recurrence	Atypical meningioma	2
2013	First gamma knife radiosurgery	Residual tumor	-
2014	Third craniotomy for recurrence	Atypical meningioma	2
2018	Second gamma knife radiosurgery	Residual tumor	-
2020	Admission; imaging showed tumor progression and pulmonary nodules	-	-
2020	Fourth craniotomy (parieto‑occipital parafalcine meningioma; Simpson grade 2 resection)	Atypical meningioma	2
2020	CT‑guided lung biopsy	Metastatic meningioma	-
2020	Radiofrequency ablation of pulmonary metastases	-	-
Last follow‑up	Stable pulmonary metastases; intact neurological function	-	-

Table 1: Summary of clinical course, treatments, and pathological findings. The table outlines the chronological clinical events, treatments, pathological diagnoses, WHO grades (where applicable), and follow-up outcomes.

Discussion

Meningioma is a slow-growing extra-axial dural-based neoplasm, with an annual growth rate of <1 cm¹. WHO grade 3 malignant meningiomas account for approximately 1% of cases and may arise de novo or progress from lower grade tumors⁹. Distant metastasis of meningioma is rare, with an overall incidence <1%, and the lung is the most common metastatic site¹.

This case has several unique clinical features. The 18-year continuous follow-up is rare in similar reports and fully reflects the natural course and treatment response of recurrent metastatic meningioma. The tumor showed clear dynamic changes in pathological grade from WHO grade 3 to grade 2 during multiple recurrences, illustrating the heterogeneity and dynamic evolution of meningioma. Pulmonary metastasis was incidentally detected on routine imaging without respiratory symptoms, highlighting the value of whole-body screening for recurrent meningioma. The tumor repeatedly invaded the superior sagittal sinus, which is closely associated with hematogenous metastasis and local recurrence.

The main mechanism of distant metastasis of meningioma is hematogenous dissemination via the venous system. The tumor invades the superior sagittal sinus and other venous structures, and tumor cells enter the systemic circulation through the vertebral venous plexus and pulmonary circulation, leading to pulmonary metastasis¹⁰. In addition, repeated surgical operations may increase the risk of tumor cell shedding and metastasis. Genetic alterations, including NF2 mutation and chromosomal deletions (1p, 9p, 22q), have been reported to correlate with meningioma metastasis in previous literature, and chromosome deletions such as 9p, 1p, and 22q are also related to the occurrence of metastasis¹¹.

The Ki-67 proliferation index of primary intracranial lesions is about 10%, while that of pulmonary metastatic lesions is only about 1%, indicating that the proliferation activity of metastatic tumor cells is reduced, which may be related to the slow growth of metastatic lesions and good clinical prognosis. EMA and Vimentin are positive in both primary and metastatic lesions, which is consistent with the immunophenotype of meningioma and helps to confirm the source of metastatic tumors.

For treatment strategy, microsurgical resection remains the first choice for recurrent intracranial meningiomas with mass effect. Total resection is difficult for tumors invading venous sinuses, so adjuvant radiotherapy is required. Gamma Knife stereotactic radiosurgery is suitable for residual or recurrent small lesions and provides effective tumor control with minimal trauma. For asymptomatic pulmonary oligometastases, radiofrequency ablation is a safe and effective minimally invasive option that avoids the morbidity of thoracotomy^12,13. Currently, there is no standard chemotherapy for metastatic meningioma. Systemic therapy was not administered to this patient.

Several clinical insights can be drawn from this case. Meningiomas with venous sinus invasion, high pathological grade, and multiple recurrences require long-term whole-body imaging follow-up for early detection of distant metastasis. The pathological grade of recurrent meningioma may change dynamically, so postoperative pathological reevaluation is necessary to guide subsequent treatment. Minimally invasive approaches such as Gamma Knife and radiofrequency ablation are safe and effective for recurrent metastatic meningioma and can improve patient quality of life. Long-term follow-up is crucial for prognostic evaluation, and larger clinical studies are needed to establish standardized diagnostic and therapeutic protocols. This single-case report has inherent limitations, but the 18-year management experience provides a valuable clinical reference for recurrent metastatic meningioma.

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
3.0T MRI Scanner	Siemens Healthcare	/	MAGNETOM Skyra 3.0T
64-Slice CT Scanner	GE Healthcare	/	LightSpeed VCT 64
DSA Machine	Philips Healthcare	FD20
EMA Antibody	Dako Agilent	M0613
Gamma Knife System	Elekta AB	/	Leksell Gamma Knife Perfexion
HE Staining Kit	Solarbio	G1120
Ki-67 Antibody	Dako Agilent	M7240
Radiofrequency Ablation System	AngioDynamics Inc.	RITA 1500X
Vimentin Antibody	Dako Agilent	M0725