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Author Affiliations: University of Massachusetts Medical School, Worcester.
A 59-year-old man presented with a 6-month history of headaches. Magnetic resonance imaging of the brain showed an enhancing extraaxial mass in the right frontal area and marked midline shift (Figure 1A). Histologic features of the tumor (Figure 2A and B) were consistent with an atypical meningioma (World Health Organization grade II). The Ki-67 proliferative index was 8.9% with a mitotic index of 12.6 mitoses/10 hpf. CD44 immunostaining was slightly positive in only a few regions. Recurrence a year later showed histologic features of an anaplastic meningioma (World Health Organization grade III) with a Ki-67 proliferative index of 32%, mitotic index of 18 mitoses/10 hpf, and more intense and diffuse immunoreactivity for CD44. A technetium Tc 99m–methylene diphosphate bone scan (Figure 1B) was performed 2 months after resection of the recurrence showing multiple lytic lesions in the ribs, sternum, and L4 vertebra. A large soft tissue mass in the right gluteus maximus muscle was also seen (Figure 1C), with the biopsy specimen showing spindle and epithelioid-appearing cells that were morphologically identical to the patient's anaplastic meningioma (Figure 2C). Epithelial membrane antigen (Figure 2D) and CD44 immunostains were positive.
Figure 1. Magnetic resonance imaging and bone scan. A, Postcontrast coronal magnetic resonance imaging sequence showing a right frontal extraaxial enhancing mass with midline shift. B, Bone scan showing several areas of increased uptake corresponding to lytic lesions. C, Magnetic resonance image of the pelvis with gadolinium showing an enhancing soft tissue mass (arrow) in the right gluteus maximus muscle.
Figure 2. Histologic analyses. A and B, Atypical meningioma showing focal necrosis (A), sheetlike growth (B), and cells with prominent nucleoli (B) (hematoxylin-eosin, original magnification ×20 [A] and ×40 [B]). C and D, Metastatic meningioma in gluteal muscle. The histologic features are nearly identical to the intracranial tumor (hematoxylin-eosin, original magnification ×20 [C] and epithelial membrane antigen, original magnification ×20 [D]). E and F, CD44 immunohistochemistry. The initial intracranial tumor (E) shows only slight focal CD44 staining compared with more intense diffuse staining in the recurrent tumor (F) (CD44, original magnification ×10 [E and F]).
Extracranial metastases occur in 0.1% of patients with meningioma, with the lungs and intra-abdominal organs being the preferred site of metastasis.1 While metastases to bone, though rare, have been described, to our knowledge, this is the first biopsy-proven metastasis of a meningioma to muscle. Bock2 and Batson3 both showed how the connection between the internal iliac veins, which drain the gluteus maximus via the gluteal veins and the epidural venous plexus, could lead to “paradoxical metastasis.” Extracranial metastases are rare not just for meningioma but also for other more malignant primary brain tumors like glioblastoma multiforme (incidence <1%) and medulloblastoma (incidence around 7.1%). While the lungs are the most frequent site involved in glioblastoma multiforme, medulloblastoma preferentially metastasizes to bone.
The progression in histological grade from atypical to anaplastic in this case is also unusual, with the chance of progression being about 2%.4 This is in contrast to gliomas, where molecular and genetic studies have identified alteration of a number of genes that may play an important role in glioma progression including amplification of epidermal growth factor receptor, loss of heterozygosity of chromosome 10, and mutation of p53. In our patient, there were 2 immunohistochemical markers that are associated with aggressive behavior. CD44 is a cell-surface adhesion protein whose presence is thought to be associated with a higher histologic grade and local invasion (though large studies with consistent results are not available). CD44 staining was only minimally and focally apparent in the initial atypical tumor but was much more intense and diffuse in the recurrent anaplastic tumor (Figure 2E and F). The Ki-67 proliferative index, which in our patient increased from 8.9% in the original tumor to 32% in the recurrence, measures the percentage of cells in the active phase of the cell cycle, generally showing good correlation with the histologic grade of a meningioma.5 It may be especially useful in predicting the growth rate and propensity for recurrence within tumors of the same grade. This case further underscores the importance of immunohistochemical markers of tumor proliferation in the histologic evaluation of meningioma.
Correspondence: Dr Cachia, University of Massachusetts Medical School, 55 Lake Ave N, Worcester, MA 01655 (email@example.com).
Published Online: July 9, 2012. doi:10.1001/archneurol.2012.1
Author Contributions:Study concept and design: Cachia, Alderson, Smith, and Yunus. Acquisition of data: Cachia, Smith, and Yunus. Analysis and interpretation of data: Cachia, Smith, and Yunus. Drafting of the manuscript: Cachia, Alderson, Smith, and Yunus. Critical revision of the manuscript for important intellectual content: Yunus. Administrative, technical, and material support: Cachia and Smith. Study supervision: Alderson and Yunus.
Financial Disclosure: None reported.
Cachia D, Alderson L, Smith T, Yunus S. Widely Metastatic Meningioma. Arch Neurol. 2012;69(10):1372–1373. doi:10.1001/archneurol.2012.1
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