CASE REPORT
Multiple Myxoid Meningiomas Exhibiting Rapid Growth: A Case Report and Literature Review
2025 年 12 巻 p. 15-20
詳細
2025 年 12 巻 p. 15-20
Myxoid meningioma is an extremely rare subtype of metaplastic meningioma, with only 17 cases reported in the literature. We present the case of an 85-year-old male who was diagnosed with multiple brain tumors following a magnetic resonance imaging scan that was performed because of progressive cognitive decline and aphasia for over 1 month. The tumors were located in the left anterior cranial fossa, left middle cranial fossa, and along the left sphenoid ridge. Gross total resection was performed on the tumors in the sphenoid ridge and middle cranial fossa. Histopathological examination confirmed the diagnosis of myxoid meningioma, although necrosis and increased cellular density suggested the possibility of an atypical meningioma. This is the first reported case of multiple lesions in a myxoid meningioma. Although myxoid meningiomas are classified as World Health Organization grade 1, their potential for rapid growth and clinically aggressive behavior warrant careful attention.
Myxoid meningioma is an extremely rare subtype of metaplastic meningioma, pathologically classified as a World Health Organization (WHO) grade 1,1) with only 17 cases reported in the past.2-14) We report a case in which we performed gross total resection of symptomatic multiple meningiomas that exhibited rapid growth and were subsequently diagnosed as myxoid meningioma. To our knowledge, this is the first reported case of multiple myxoid meningiomas. Although pathologically classified as WHO grade 1, myxoid meningiomas can sometimes be clinically malignant and warrant careful monitoring.
An 85-year-old male was admitted because of progressive cognitive decline and aphasia over the course of 1 month. Computed tomography (CT) and magnetic resonance imaging (MRI) suggested multiple brain tumors (Fig. 1A-C). MRI revealed lesions measuring 38 × 50 × 62 mm at the left sphenoid ridge, 25 × 20 × 15 mm at the left middle cranial fossa, and 8.3 × 6.8 × 9.0 mm at the left anterior cranial fossa. All tumors were located along the dura mater and showed strong uniform gadolinium enhancement (Fig. 1D-F). The lesions exhibited mild peripheral edema despite their size, were hyperintense on T2-weighted images (Fig. 1C), lacked calcification, and showed no decrease in apparent diffusion coefficient.
CT and MRI following cognitive decline. (A) CT shows a brain tumor at the left sphenoid ridge, with no calcification. (B) T1WI presenting tumors showing hypo-intensity. (C) T2WI demonstrate the tumors showing hyper-intensity, along with mild cerebral edema at the margins of the tumor in the left sphenoid ridge. (D-F) Gadolinium-enhanced T1 MRI presents the location of the tumors in the left sphenoid ridge, middle cranial fossa, and anterior cranial fossa, all along the dura mater, with uniform enhancement and well-defined margins.
CT: computed tomography; MRI: magnetic resonance imaging; T1WI: T1-weighted image; T2WI: T2-weighted image
Three years prior to admission, CT revealed no apparent abnormalities (Fig. 2A). Two years before admission, an MRI revealed lesions measuring 14 × 10 × 10 mm at the left sphenoid ridge and 8.5 × 8.5 × 5.0 mm at the left middle cranial fossa (Fig. 2B-C). Because of the small size of the lesion, lack of symptoms, lack of family history, and the advanced age of the patient, follow-up was not conducted. However, given the rapid growth and progression of the symptoms, tumor removal was later deemed appropriate. Therefore, we resected the tumors at the left sphenoid ridge and the middle cranial fossa, which were accessed via the same craniotomy.
(A) A CT scan, 3 years prior to admission, shows no significant abnormalities. (B, C) FLAIR MRI 2 years prior to admission shows a suspected extrinsic brain tumor at the left sphenoid ridge and a retrospectively noted suspicious lesion at the middle cranial fossa.
CT: computed tomography; FLAIR: fluid attenuated inversion recovery; MRI: magnetic resonance imaging
On the first day of hospitalization, a preoperative embolization was performed. Angiography of the left internal carotid artery revealed tumor staining on the surface, but no significant feeders for embolization were observed. In contrast, angiography of the left external carotid artery identified feeders to the tumor, primarily from the anterior convexity branch of the middle meningeal artery (MMA), supplying the sphenoid ridge tumor, and the petrosal branch of the MMA, supplying the middle cranial fossa tumor. The anterior convexity branch of the MMA showed no contrast agent flow into the orbit (Fig. 3A). After coil embolization of the anterior branching vessel, embolization was carried out using 100-300 μm Embosphere® microspheres (trisacryl gelatin microspheres; Nippon Kayaku, Tokyo, Japan). Since an arteriovenous fistula within the tumor persisted, additional coil embolization was performed at the origin of the MMA. Although feeders from the accessory meningeal artery remained, most of the tumor was no longer stained, and the procedure was concluded at this point (Fig. 3B).
(A) Initial left external carotid artery angiography shows the anterior convexity branch of the middle meningeal artery supplying the tumor at the sphenoid ridge and the petrosal branch acting as a feeder to the tumor in the middle cranial fossa. (B) Post-embolization left external carotid artery angiography shows that the majority of the tumor is no longer stained, and the arteriovenous fistula has disappeared.
A left frontotemporal craniotomy was performed to remove the tumor completely after dissection from the surrounding normal brain tissue. Adhesion between the tumor and the brain was minimal, making dissection relatively easy. The dura mater at the tumor attachment sites, including the middle cranial fossa and tentorium, was coagulated and cauterized to achieve Simpson grade 2 resection. Postoperative MRI confirmed the complete removal of the tumor. No new postoperative symptoms were observed; however, mild motor aphasia persisted. Therefore, the patient was transferred to a rehabilitation hospital for recovery before discharge. At the 4-month postoperative follow-up with contrast-enhanced MRI, no residual or recurrent tumor was observed. However, the tumor at the anterior cranial fossa had increased to 10 × 8.5 × 12 mm; therefore, the patient underwent radiotherapy.
Consent for publication was obtained from the patient and his family.
Pathological findingsThe pathological diagnosis was "Myxoid meningioma, most likely, cannot exclude WHO Grade 2." The cellular morphology, comprising spindle-shaped cells arranged in fascicles or a complex pattern, was set in a myxoid stroma, suggesting differentiation or metaplasia toward mesenchymal tissue (Fig. 4A-B). The tumor was positive for Alcian blue staining (Fig. 4C) and lacked chordoma-like epithelium and various mesenchymal components, such as bone or fat, leading to the diagnosis of myxoid meningioma. The tumor was also positive for epithelial membrane antigen (EMA), vimentin, progesterone receptor, and somatostatin receptor 2A and negative for neuronal nuclei, cluster of differentiation 56, and S100 (Fig. 4D). Additionally, the clinical course and extensive myxoid tumor necrosis-like changes were observed, despite being within the scope of metaplasia. Moreover, there were areas of increased cellular density and small cell morphology, with Ki-67 showing 2%-3% in most areas but mildly elevated to 7%-8% in some regions (Fig. 4E). However, even in these regions, no clear nucleolar prominence or evidence of mitosis was observed (0/10 high-power fields). Therefore, the diagnosis of atypical meningioma, WHO grade 2, could not be excluded. IDH1-R132, IDH2-H174, TERTC228, and TERTC250 were all wild type, with no 1p-19q codeletion or CDKN2A/B homozygous deletion.
(A, B) H&E staining (A: 40×, B: 100×) reveals spindle-shaped cells with elongated nuclei, sparsely proliferating in fascicular or interlacing patterns against a background of highly edematous myxoid stroma. The degree of atypia is not pronounced, and mitotic figures are absent. (C) Alcian Blue staining (40×) shows diffusely positive cells. (D) EMA staining (40×) shows numerous EMA-positive cells. (E) K-i67 immunohistochemical staining (100×) shows 7%-8% nuclear positivity in some regions.
EMA: epithelial membrane antigen; H&E: hematoxylin and eosin
Currently, there are 15 subtypes of meningiomas.1) Among them, metaplastic meningioma is a rare subtype classified as WHO grade 1. According to a 15-year study conducted in France, the incidence of meningiomas is 0.04% (62 of 13,038).15) Based on the predominant mesenchymal components, this subtype is further divided into categories such as osseous, lipomatous, cartilaginous, myxoid, and xanthomatous, either singly or in combination,1) with osseous and lipomatous being the most common.16) Among these, myxoid meningiomas are rare, with only 17 cases reported to date.2-14)
Pathological and immunohistochemical analyses are crucial for the diagnosis of myxoid meningiomas, which are characterized by the excessive presence of mucinous substances, such as hyaluronic acid and chondroitin sulfate, within the cytoplasm and stain positively with Alcian blue.2) Furthermore, it has been noted for its lack of reactivity with laminin.4) Immunohistochemically, myxoid meningiomas are positive for vimentin and EMA, suggesting a meningeal epithelial origin. To rule out other malignant diseases, additional markers such as cytokeratin (positive in myxoid tumors and chordomas), S-100 (positive in schwannomas and neurofibromas), and glial fibrillary acidic protein (positive in chordoid glioma) are used.8,9) Chordoid meningioma, classified as WHO grade 21) is an important differential diagnosis owing to its pathological similarities with myxoid meningiomas and higher malignancy risk. Chordoid meningioma is characterized by chordoma-like epithelium with strong nuclear atypia and fewer cytoplasmic vacuoles arranged in a reticular pattern or by lymphocyte infiltration associated with Castleman disease.17)
In the present case, the pathological diagnosis was myxoid meningioma, and the criteria for meningioma, corresponding to WHO grade 2, were not met. Although the influence of preoperative embolization cannot be excluded, some specimens exhibited necrosis-like changes in the myxoid tumors. Additionally, partial increases in cellular density, the presence of small cells, and elevated Ki-67 (7%-8%) suggested the possibility of atypical meningioma. However, no findings suggestive of a genetic malignancy were observed.
Multiple meningiomas have been reported to occur in 1%-10% of patients with meningioma;18) however, a recent Surveillance, Epidemiology, and End Results study reported an incidence as high as 19%.19) The causes of multiple meningiomas can be categorized into idiopathic cases and those associated with genetic mutations, such as neurofibromatosis type 2 and radiation-induced tumors.18) Each additional lesion is associated with a decrease in overall survival.19) Pathologically, the likelihood of finding at least one meningioma with WHO grade 2 or higher is reported to be 22%,20) suggesting that the malignancy level is comparable to or slightly higher than that of single meningioma. Furthermore, individual meningiomas commonly differ in subtype or grade.20)
Table 1 summarizes the age, sex, tumor size, T2 intensity, presence of calcification, presence of edema and surgical decision outcomes of 17 previous cases of myxoid meningioma. The average age of the patients was 40.0 years (standard deviation, 18.7), with a predominance of females (11/17). The median maximum tumor diameter at the time of resection was 42 mm (interquartile range, 20-60). All patients with available MRI data exhibited T2 hyperintensities. In the 11 cases where gross total resection was achieved, there were no reports of recurrence. Conversely, there have been reports of tumors that increased in size from 3 × 3 mm to 74 × 124 × 110 mm over 3 years,9) cases with recurrence after 2 years in lesions extending to the inferior turbinate despite surgery,9) and cases where rapid growth requiring reoperation occurred just 8 months after partial resection.12)
Summary of previous cases of myxoid meningioma
| Authors | age/sex | size (mm) | T2 intensity | calcification | edema | surgical decision |
|---|---|---|---|---|---|---|
| Abbreviations: NA, not available; GTR, gross total resection; PR, partial resection | ||||||
| D. Harrison and P. E. Rose2) | 23/M | NA | NA | NA | NA | NA |
| D. Harrison and P. E. Rose2) | 70/F | NA | NA | NA | NA | NA |
| Lois R. Bégin3) | NA | NA | NA | NA | NA | NA |
| Yoko Kimura, et al.4) | 25/M | NA | NA | - | + | GTR |
| Mahlon D. Johnson, et al.5) | 31/F | 78×46 | NA | NA | + | GTR |
| Mohanpal Singh Dulai, et al.6) | 7/F | 48 | hyper | NA | + | GTR |
| Khaled M. Krisht, et al.7) | 50/F | 60×60×40 | hyper | - | NA | GTR |
| Javier Ortiz, et al.8) | 43/F | 10 | NA | NA | NA | GTR |
| Mahlon D. Johnson and Ali Hussain9) | 33/F | 3×3→74×124×110 | hyper | - | - | NA |
| Mahlon D. Johnson and Ali Hussain9) | 64/F | 13 | hyper | - | + | GTR |
| Mahlon D. Johnson and Ali Hussain9) | 74/F | 37×35×37 | hyper | + | + | NA |
| Mahlon D. Johnson and Ali Hussain9) | 36/M | NA→19×20×15 | NA | NA | NA | NA |
| Akiko Marutani, et al.10) | 44/F | 9×9 | hyper | - | + | GTR |
| Seema Rehar, et al.11) | 40/F | 80×50×50 | NA | NA | + | GTR |
| Henri Salle, et al.12) | 33/M | 42×31×37 | NA | NA | NA | PR→GTR |
| Aziz Bedioui, et al.13) | 14/M | 48×37.5×49 | hyper | NA | + | GTR |
| Norris C. Talbot, et al.14) | 46/F | 21×23×28→26×26×28 | NA | NA | NA | GTR |
This myxoid meningioma case is unique among the 17 previously reported cases owing to the presence of multiple lesions that rapidly enlarged and became symptomatic, necessitating surgery. The pathological examination revealed partial necrosis and nuclear abnormalities. Although myxoid meningiomas are classified as WHO grade 1, they have the potential to follow a clinically malignant course and warrant careful attention.
We report a case of a multiple myxoid meningioma that rapidly enlarged and became symptomatic, necessitating surgery. Although myxoid meningiomas are classified as WHO grade 1, they have the potential to follow a clinically malignant course and warrant careful attention.
We sincerely thank Dr. Shinya Tanaka from the Department of Cancer Pathology at Hokkaido University for his invaluable support with the pathological diagnosis in this study. We would also like to thank Editage (www.editage.jp) for English language editing.
Informed consent was obtained from the patient for the publication of this case report and the accompanying images.
All authors have no conflict of interest.
