Secretory meningioma

Differential expression of CD44 variants among meningioma subtypes

Aims/background-CD44 is a widely distributed cell surface molecule which has numerous isoforms generated by alternative splicing. The diverse functions related to the CD44 variants (CD44v) have been reported in various physiological and pathological conditions. The pattern of expression of CD44v among meningioma subtypes was investigated to ascertain whether CD44 variants play a role in a variety of biological processes, such as epithelial differentiation and extracranial metastasis.Methods-Twenty three meningiomas were studied immunohistochemically using novel antibodies directed against CD44 isoforms. Six of the 23 samples were analysed by reverse transcription polymerase chain reaction (RT-PCR), followed by Southern blotting with CD44v specific probes.Results-In meningothelial, fibrous and anaplastic meningiomas, a standard form of CD44 was detected by RT-PCR and was homogeneously expressed in tumour cells when studied immunohistochemically. CD44v was not detected in these subtypes. In secretory meningiomas, however, CD44v isoforms were strongly expressed in the cell clusters that produce secretory granules and also accumulated in the granules. The population of tumour cells immunopositive for CD44v was similar to that which stained with antibodies directed against carcinoembryonic antigen, epithelial membrane antigen and ezrin. On RT-PCR with Southern blotting, only the secretory type showed high level expression of CD44v.Conclusions-CD44v in meningiomas is expressed in relation to tumour cell differentiation towards the epithelial type.

Secretory meningiomas: a benign subgroup causing life-threatening complications

While meningiomas are known as slow-growing extracerebral neoplasms, the subgroup of secretory meningiomas with histologically benign characteristics tend to cause disproportional peritumoral edema, frequently leading to severe medical and neurological complications in postoperative management. Among 1,484 meningiomas that were resected at our institution between 1990 and 2007, 44 (3%) patients were found to have the histological diagnosis of a secretory meningioma. The clinical course, radiological appearance, and histopathological features were retrospectively analyzed to examine the specifics of these benign lesions. Meningiomas were located at the convexity (n = 14), the cranial base (18), and the sphenoid ridge (12). A severe, nearly hemispheric perifocal edema disproportional to tumor size was seen on preoperative MR imaging in 18 (41%) patients. Following surgical resection, the postoperative course was uneventful in 29 patients. In 15 patients, severe peritumoral edema continued or even increased on postoperative CT imaging. Six patients showed midline shift and clinical worsening necessitating respirator-assisted ventilation and intracranial pressure monitoring. An association between the extent of brain edema and number of periodic acid Schiff-positive pseudopsammomas was found (p < 0.02). Further, the size of the edema correlated with the number of immunohistochemically detected cells expressing carcinoembryonic antigen (CEA) and cytokeratin (CK) (p < 0.01). Mean MIB-1 (Ki-67 antigen) proliferation index was 3.0% (range, 0%-17%) and did not correlate with edema or tumor recurrence. Secretory meningiomas are frequently associated with severe peritumoral edema. The extent of edema correlates with immunohistochemically detected expression of CEA and CK. Extended perifocal edema in meningiomas is an unusual finding and should alert the neurosurgeon that surgery may aggravate edema excessively, leading to a life-threatening postoperative situation.

Merlin Expression in Secretory Meningiomas: Evidence of an NF2-independent Pathogenesis?

One of the most common chromosomal regions implicated in the meningiomas tumorigenesis is 22q12 where the neurofibromatosis 2 (NF2) gene resides. The NF2 tumor-suppressor gene encodes for the merlin/schwannomin protein, which is responsible for the inherited disease neurofibromatosis 2. NF2 gene mutations predominantly occur in transitional and fibroblastic meningiomas, whereas the meningothelial variant is less affected. Secretory meningioma is an infrequent meningioma subtype. Its most typical morphologic feature is the presence of intracytoplasmic or extracytoplasmic round hyaline, eosinophilic, and periodic acid Shiff-positive bodies in a lesion frequently otherwise classifiable as meningothelial meningioma. This study reviews the immunohistochemical merlin expression in 14 consecutive secretory meningiomas. Our purpose was to investigate if secretory meningiomas, analogous to meningothelial meningiomas, follow a molecular route of pathogenesis independent of the neurorofibromatosis 2 gene-associated pathway. All meningiomas showed positive immunocoloration involving the majority of the hyaline inclusions and secretory cells; in 12 (86%) meningiomas, a positive immunoreaction was also documented in nonsecretory tumoral cells. Our results may indicate a molecular, besides morphologic, similarity between secretory and meningothelial meningiomas: the almost constant merlin immunohistochemical expression in our series gives evidence for a possible NF2 gene-independent pathogenesis in secretory meningiomas.

Secretory meningioma: immunohistochemical findings and evaluation of mast cell infiltration

Secretory meningiomas constitute a relatively rare subtype of meningiomas, accounting for only 1.1% at our institution, with a 6:1 predominance of female patients. This study aimed to obtain more information about the immunohistochemical characteristics of this histological entity, and to analyse the effects of histological factors such as the presence of mast cells on the radiological evidence of surrounding tumour oedema that frequently occurred in this subtype of meningioma. Fourteen cases of secretory meningioma were examined. Relevant clinical information was obtained from the patient files. Peritumoural oedema was determined either by CT or MRI scans and graded as small, moderate and severe. In order to perform the quantitative evaluation of mast cells in secretory meningiomas in a comparison with other meningiomas, 14 non-secretory meningiomas were randomly selected and used as a control group. The immunohistochemical staining of carcinoembryonic antigen was positive within the secretory droplets and the cells surrounding them in all cases. Ki 67 (MIB 1) proliferative index mean values were 2.4%, indicating low expression in all secretory meningiomas. Moreover, from our statistical analysis, there is no clear-cut pattern of various types of cytokeratins emerging in secretory meningiomas. The secretory meningiomas were characterized by a significantly increased number of mast cells as compared with non-secretory meningiomas of different grades. As the present clinical findings and laboratory results could not confirm a correlation between mast cell density and radiological evidence of oedema, further studies of mediators are warranted.

Secretory meningiomas

Secretory meningiomas are a rare meningioma subtype. Among meningiomas, the frequency of secretory meningiomas is 1.6%. Unlike other meningioma types, most of the patients were female (ratio 3:1). No recurrence was reported during the 24-180 months follow-up period of our secretory meningiomas in which, a low level of 0.3% Ki-67 proliferative index was reported. In this meningioma subtype, the percentage of cases with positive progesterone receptor is 33%. With carcinoembryonic antigen, cytokeratin and epithelial membrane antigen, in all the cases positivity was observed in both, the inclusions and the cells surrounding them. With human milk fat globulin 2, a high ratio (92%) of positivity was observed. Majority of the cases were negative with CA125, only three of the cases had suspicious positivity. Distribution of inclusions was irregular and their positive reactions showed varying staining features. Positivity with alpha-1-antitripsin was seen not only in the inclusions but also in some meningothelial cells as well. Ubiquitin was positive in inclusions of the 83% of cases. Staining features of the inclusions pointed out the possibility of them being in a varying age and/or content. Secretory meningiomas are a different type compared to other meningiomas, not only with their histological features but also with their clinical features as well.

Secretory meningiomas: clinical and immunohistochemical observations

OBJECTIVE

Secretory meningiomas are a rare histological subtype of these benign intracranial tumors. Few reports have been published regarding their tendency to develop peritumoral edema.

METHODS

Between July 1994 and February 1999, 11 patients with secretory meningiomas underwent operations in the Department of Neurosurgery, University of Kiel, Kiel, Germany. The clinical notes and radiological data (computed tomographic and magnetic resonance imaging scans) were reviewed. Immunohistochemistry was used to examine the expression of carcinoembryonic antigen and epithelial membrane antigen as well as progesterone and estrogen receptors.

RESULTS

Secretory meningiomas were found in 11 (5%) of 214 patients with intracranial meningiomas who were operated on in that period. All 11 patients were women. These patients' mean age was 65 years (range, 51-87 yr). The localization of these tumors was at the convexity in seven patients, at the sphenoid ridge in two patients, and in the olfactory groove and petroclival region in one patient each. Two meningiomas had no edema surrounding them, two meningiomas had a small amount of edema, two had moderate edema, and five had severe edema. No recurrences were observed during the mean follow-up period of 26 months (range, 8-65 mo). Immunohistochemically, all tumors contained pseudopsammoma bodies and reacted with epithelial membrane antigen and carcinoembryonic antigen. The MIB-1 antibody staining index showed a mean of 2% (range, 0-7%).

CONCLUSION

Secretory meningiomas are rare tumors, and they are mainly localized at the frontal convexity and the sphenoid ridge. They are surrounded by more edema than usual. The preponderance of female patients with this presentation is striking. The expression of carcinoembryonic antigen and epithelial membrane antigen is a characteristic feature of secretory meningiomas. These meningiomas are also positive for progesterone receptors, which has been shown to be a good prognostic factor.

[Secretory meningioma. Report of two cases]

Two surgically removed meningotheliomatous meningiomas with hyaline inclusions or pseudopsammoma bodies were studied. Both meningiomas showed expression of carcinoembryonic antigen and cytokeratin in the cells surrounding the hyaline bodies. There was widespread vimentin and epithelial membrane antigen except in the cells with hyaline inclusions. Clinically both had a severe cerebral edema. One of the cases showed multiple tumors, probably meningiomas. It is important not to misinterpret this variant of meningioma as metastatic neoplasm which may result in palliative treatment of a potentially curable tumor.

Secretory meningioma: clinical, histologic, and immunohistochemical findings in 31 cases

BACKGROUND

Secretory meningioma is a rare histologic variant characterized by a unique epithelial differentiation of meningothelial cells resulting in the production of hyaline inclusions. Most previous reports have presented single case observations. The authors selected 31 cases for a clinicopathologic study to characterize this type of tumor further.

METHODS

Clinical data were compiled and the extent of peritumoral edema was assessed from preoperative computed tomography or magnetic resonance imaging scans. Preparations of surgical specimens of all tumors were studied after both conventional histologic and immunohistochemical preparations were made. Immunostaining was performed by either the avidin-biotin complex method or the alkaline phosphatase-antialkaline phosphatase method using 22 primary antibodies.

RESULTS

In the tumor collection used in this study, secretory meningiomas represented 3% of meningiomas. The female-to-male ratio was 9:1. Most tumors were located at the sphenoid ridge or at the frontal convexity, and recurrences were not observed. Eighty-four percent of tumors presented with slight to marked peritumoral edema. The MIB-1 staining index showed a mean of 3.8%. Inclusions and surrounding cells consistently expressed epithelial membrane antigen, cytokeratins, carcinoembryonic antigen, and carbohydrate antigen 19-9. In decreasing frequency, they also contained alpha1-antitrypsin, immunoglobulin (Ig)A, alpha1-antichymotrypsin, IgM, and IgG. Cells positive for vimentin and S-100 did not contain inclusions. All tumors were positive for progesterone receptors. Macrophages were stained with antibodies to factor XIIIa, human leukocyte antigen-DR, and alpha1-antitrypsin. In 64% of cases, tumor vessels lacked expression of glucose transporter protein 1.

CONCLUSIONS

The classification of secretory meningioma as a distinct variant has been justified on clinical, histologic, and immunohistochemical grounds. The unique epithelial features call attention to the broad spectrum of differentiation properties found in meningiomas.