Microcystic meningioma of the calvarium: a series of 9 cases and review of the literature

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

OBJECTIVE

To evaluate the clinicopathological characteristics, radiology, and long-term outcomes of microcystic meningiomas (MM) and compare it with other subtypes of meningiomas managed at a single neurosurgical center.

METHODS

A total of 87 consecutive patients who underwent surgical resection and were diagnosed as MM between 2005 and 2016 were enrolled for analysis. Clinicopathological, radiology, and prognostic information was collected and analyzed. Progression free survival (PFS) was compared with 659 patients with other subtypes of WHO grade 1 meningiomas and 167 patients with atypical meningiomas treated during the same period.

RESULTS

Fifty six females and 31 males with MM were analyzed. Peri-tumor brain edema was frequent on T2 WI (85%).12 patients (13.8%) experienced tumor progression during the mean follow-up of 101.66 ± 40.92 months. The median PFS was unavailable, and the 5, 10, and 15 year progression-free rates were 96.9%, 84.0%, and 73.9%, respectively. Univariate COX analysis demonstrated skull base location and higher Ki-67 index as significant negative prognostic factors for PFS (P < 0.05); multivariate analysis identified tumor location and Ki-67 index as independent factors (P < 0.01), as well. Of note, the PFS of MM was worse than other WHO grade 1 subtypes (P < 0.001), but better than atypical meningiomas (P < 0.001), and the PFS differences were retained even when the analysis was limited to the patients receiving GTR (P < 0.05).

CONCLUSION

The PFS of MM was worse than other WHO grade 1 subtypes and better than atypical meningiomas. Skull base location and higher Ki-67 index were independent negative prognostic factors in MM.

Fronto-orbito-ethmoidal intradiploic meningiomas: A case study with systematic review

Background

Primary intradiploic meningiomas, extra-axial tumors arising primarily in the skull, are rare. The authors reported a complex case of intradiploic intraosseous metaplastic meningioma of the left medial wall and orbital roof with the left frontal sinus invasion and left ethmoidal body bone substitution. The authors also conducted a systematic review concerning diagnosis and management of patients affected by purely calvarial intradiploic meningiomas along with a focus on fronto-orbito-ethmoidal ones.

Methods

A literature search was conducted using PubMed and Scopus databases according to preferred reporting items for systematic reviews and meta-analysis statement and with the following Mesh terms: Intradiploic, intraosseous, calvarial, and meningioma. Eligibility criteria were limited by the nature of existing literature on intradiploic meningiomas, consisting of only case series, and case reports.

Results

A total of 128 published studies were identified through our search. 41 studies were included in this systematic review, 59 patients with a female/male ratio of 1.2/1. The mean age of the patients is of 47.69 years (range 3-84 years). Only seven out of 59 patients (11.9%) presented a complex intradiploic meningioma located in fronto-orbito-ethmoidal region like our case. In almost all patients, a gross-total resection was performed (96.6%) and only in two patients (3.4%) a subtotal resection was achieved.

Conclusion

The authors shared this successfully treated case to add to the overall clinical experience in the management of this rare subtype tumor, with the hope that more studies are conducted to further address the mechanism of intradiploic meningiomas development.

Microcystic Cerebral Neoplasm in a Nilgai Antelope (Boselaphus tragocamelus): Putative Microcystic Meningioma

Tumours of the nervous system are rare in wild and captive mammals. In this report, we describe an intracranial, solid, space-occupying lesion originating from the meninges in a Nilgai antelope (Boselaphus tragocamelus). Histologically, the tumour had a conspicuous microcystic appearance with features similar to the histological subtype of microcystic meningioma described in humans. This is the first such tumour reported in this species.

Calvarial ectopic meningothelial meningioma

BACKGROUND

Meningiomas are the most common benign neoplasm of the brain whereas ectopic presentation, although reported, is rare. Among these ectopic tumors, there are a group of purely intraosseous meningiomas, which usually are diagnosed differentially from common primary osseous tumor such as fibrous dysplasia and osteoid osteoma.

CASE DESCRIPTION

We report a 62-year-old female with a history of headaches and 6 months of progressive right parietal bulging, with no neurological signs. Parietal craniotomy was performed with immediate titanium cranioplasty of the parietal convexity. Histopathology exams revealed an ectopic intradiploic meningioma without invasion of cortical layers, with positive staining for progesterone receptors and epithelial membrane antigen.

CONCLUSIONS

Ectopic intraosseous meningiomas remain a rare neoplasm with only a few cases reported. The main theories to justify the unusual topography appear to be embryological remains of neuroectodermal tissue or cellular dedifferentiation. Surgical treatment seems the best curative option.