Distinct clinical outcome of microcystic meningioma as a WHO grade 1 meningioma subtype

Clinical and molecular characteristics and long-term outcomes of pediatric intracranial meningiomas: a comprehensive analysis from a single neurosurgical center

BACKGROUND

Meningioma represents the most common intracranial tumor in adults. However, it is rare in pediatric patients. We aimed to demonstrate the clinicopathological characteristics and long-term outcome of pediatric meningiomas (PMs).

METHOD

We enrolled 74 patients with intracranial PMs and analyzed their clinicopathological characteristics. Targeted next generation sequencing was used to detect alterations in meningioma relevant genes. Progression-free survival (PFS) was compared between PMs and adult meningiomas (AMs). Univariate and multivariate Cox analyses were employed to evaluate the predictive values of clinicopathological characteristics. A nomogram was constructed and its predictive accuracy evaluated.

RESULT

40 females (54.1%) and 34 males (45.9%) patients, with the gender ratio of 1.18:1, were identified. 9 (12.2%) cases were clinically diagnosed as NF2-related Schwannomatosis (NF2-SWN), while 65 (87.8%) were sporadic. Ventricular location was found in 16 patients (21.6%). 19 patients (25.7%) experienced recurrence during a median follow-up period of 33 months (range 2 -145.25 months). The 3-, 5-, and 8-year PFS rates was 74.74%, 74.74%, and 59.38%, respectively. The PFS of the PM and AM cohorts were not significantly different, with or without propensity score matching. NF2 mutation was observed in 33 sporadic PMs (52.4%), whereas alterations in other genes (AKT1, TRAF7, SMO, PIK3CA, KLF4) frequently mutated in AMs, were not identified. The proportion of NF2 mutation in PMs was significantly lower in the skull base than other locations (p = 0.02). One anaplastic PM harbored TERT promoter mutation. Of note, in sporadic PMs, NF2 mutations were not significantly associated with PFS (p = 0.434) or overall survival (OS) (p = 0.60). The multivariate Cox analysis showed NF2-SWN (p < 0.001) and extent of resection (p = 0.013) to be independently associated with the PFS of PMs. Our prognostic model showed predictive accuracy for long-term PFS in PMs as the 3-, 5- and 8-year Area Under the Curve (AUC) was 0.927, 0.930, and 0.870, respectively.

CONCLUSION

PM was characterized by its relative male predominance, ventricular location, NF2-SWN, and NF2 mutation. Of note, PMs had similar prognosis to AMs and NF2 alteration was not significantly associated with PFS in PMs.

Intracranial angioleiomyoma mimicking meningioma: an uncommon tumor with favorable outcome and frequent GJA4 mutation

Intracranial angioleiomyoma (IALM) is a rare neoplasm mimicking meningioma. We aimed to explore the clinical and molecular characteristics of IALMs. We included 40 patients with IALMs who had tumor resection at our center from 2009 to 2022. Clinicopathological and radiological characteristics were extracted and analyzed thoroughly. GJA4 mutation status was detected and correlated with clinical characteristics. IALMs accounted for about 10% of all angioleiomyoma and had a significant male predominance compared to extracranial angioleiomyoma (p=0.04). However, there was no age difference between extracranial angioleiomyomas and IALMs. In our IALM cohort, orbital (35%) were the most common tumor location, followed by tentorium (25.0%), cavernous sinuous (17.5%). Vision decrease, diplopia and exophthalmos (40%) were the most common symptom. The radiological characteristics of ILAMs were similar to meningiomas; 20 patients (57.1%) in our cohort were misdiagnosed as meningioma preoperatively. Gross total resection was achieved in all patients. The postoperative pathology showed median Ki-67 index was 1% (range: 0-10%). Vision improvement or exophthalmos relief was achieved in 12 of 16 patients (75.0%). During the long-term follow-up (mean 70.3 months, range 30 - 128 months), no patient experienced tumor recurrence or died of tumor progression, indicating that IALM was clinically benign. GJA4 mutation (p. Gly41Cys) was detected in 17 (42.5%) patients. Of note, the correlations analysis revealed that orbital and cavernous sinus areas (64.7%) were the leading location that harbor GJA4 mutations. Tumors with mutant GJA4 were associated with positive progesterone receptor (PR) expression (p=0.02). This first large case series demonstrated that IALM predominantly affected males, was located in the cavernous sinus and orbital areas, and often manifested visual impairment and diplopia. IALM had favorable outcome. Notably, IALMs frequently exhibited a GJA4 mutation, which was linked to the cavernous sinus and orbital locations, as well as PR expression.

Posterior fossa microcystic meningioma mimicking an arachnoid cyst

Microcystic meningioma is an uncommon subtype of World Health Organization grade 1 meningiomas often associated with a shorter progression-free survival. Diagnosis through imaging alone can often be challenging due to atypical characteristics, especially when found in unexpected locations. Here, we present a 55-year-old woman who was diagnosed, based on imaging, with a posterior fossa arachnoid cyst 5 years prior after complaints of headaches and gait imbalance. After surgical resection of the "arachnoid cyst," the diagnosis of microcystic meningioma was made. This case report emphasizes the clinical importance and challenges associated with diagnosing microcystic meningiomas.