Intracytoplasmic lumina in meningioma: an ultrastructural and immunohistological study

Epithelial differentiation with microlumen formation in meningioma: diagnostic utility of NHERF1/EBP50 immunohistochemistry

Meningioma is a primary brain tumor arising from the neoplastic transformation of meningothelial cells. Several histological variants of meningioma have been described. Here we show that NHERF1/EBP50, an adaptor protein required for structuring specialized polarized epithelia, can distinguish meningioma variants with epithelial differentiation. NHERF1 decorates the membrane of intracytoplasmic lumens and microlumens in the secretory variant, consistent with a previously described epithelial differentiation of this subtype. NHERF1 also labels microlumens in chordoid meningioma, an epithelial variant not previously known to harbor these structures, and ultrastructural analysis confirmed the presence of microlumens in this variant. NHERF1 associates with the ezrin-radixin-moesin (ERM)-NF2 cytoskeletal proteins, and moesin but not NF2 was detectable in the microlumens. In a meningioma series from 83 patients, NHERF1 revealed microlumens in 87.5% of the chordoid meningioma (n = 25) and meningioma with chordoid component (n = 7) cases, and in 100% of the secretory meningioma cases (n = 12). The most common WHO grade I meningioma variants lacked microlumens. Interestingly, 20% and 66.6% of WHO grades II (n = 20) and III (n = 3) meningiomas, respectively, showed microlumen-like NHERF1 staining of ultrastructural tight microvillar interdigitations, mainly in rhabdoid, papillary-like or sheeting areas, revealing a new subset of high grade meningiomas with epithelial differentiation. NHERF1 failed to detect microlumens in 12 additional cases of chordoid glioma of the 3rd ventricle, chordoma and chondrosarcoma, neoplasms that may mimic the histological appearance of chordoid meningioma. This study uncovers features of epithelial differentiation in meningioma and proposes NHERF1 immunohistochemistry as a method of discriminating chordoid meningioma from neoplasms with similar appearance.

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.

S100A5: a marker of recurrence in WHO grade I meningiomas

Some WHO grade I intracranial meningiomas resected from the same sites and with the same quality of resection (Simpson's grading scale) recur, while others do not. The reasons for this variability in occurrence of recurrence have not yet been determined. We therefore investigated the prognostic recurrence value of seven biological markers on a series of completely resected WHO grade I meningiomas. For this purpose, we analysed a series of 33 WHO grade I meningiomas totally resected between 1980 and 1990 (a follow-up of 10 years), including 14 cases of recurrence. The fixed tumour material from each meningioma was submitted to histochemical analyses targeting galectin-3 and its binding sites, the S100A5, S100A6 and S100B proteins, and cathepsin-B and -D. The levels of expression were assessed semi-quantitatively (in terms of the staining intensity and the labelling index) and submitted to uni- and multivariate analyses. Of all the markers investigated, only S100A5 expression can be associated with any significant prognostic value in the matter of recurrence. More particularly, the meningiomas with high levels of S100A5 staining intensity either did not recur, or recurred later than those with a low immunopositive S100A5 intensity (P = 0.004). Cox regression analyses demonstrated that this latter marker was associated with significant prognostic values independent of the patients' ages. Furthermore, the combination of the patients' ages and S100A5 staining intensity permitted the identification of a group with a particularly high risk of recurrence, that is, the patients younger than 55 and with meningiomas exhibiting low S100A5 intensities (P = 0.001). In conclusion, the S100A5 protein could play a role in the recurrence of totally resected WHO grade I meningiomas.

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 meningioma: clinicopathologic features of eight cases

The clinical and morphological features of eight patients with meningothelial meningiomas with numerous pseudopsammoma bodies (secretory meningiomas) are presented. The six female and two male patients ranged in age from 43 to 68 years. Tumours were located at the petroclival region in two, the lateral parasellar region in two, the petrous apex in one and the sphenoid ridge in three patients. On magnetic resonance imaging, they were iso or hypointense on T1-weighted images, and hyper or isointense on T 2-weighted images. Peritumoral brain edema was absent in five cases, and was mild to moderate in three cases. Serum carcinoembryonic antigen (CEA) levels were measured preoperatively in three patients, with one having an elevated serum CEA level which re turned to normal following tumour resection. Immunohistochemical analysis on the resected tumour tissues, pseudopsammoma bodies and surrounding tumour cells were shown to be CEA-positive. Ultrastructurally, pseudopsammoma bodies were composed of granular and filamentous materials located predominantly in the intracellular lumina, which were lined by microvilli. While these morphological features of focal epithelial and secretory differentiation of tumour cells call attention to the broad spectrum of differentiation properties of meningiomas, the biological behavior of the eight tumours reported herein corresponded to those of meningiomas in general.

[Supratentorial meningiomas. Diagnosis, surgical results and complications]

Meningiomas are benign tumors arisising from arachnoid cells and represent the commonest asymptomatic intracranial tumors. We analysed 69 supratentorial meningiomas managed by the Neurosurgical Tumor Group of the Clinics Hospital of Medicine School of São Paulo University (September 1995 to September 1997). Age, sex, edema degree, tumor site, surgical complications and mortality were studied. Edema degree was defined by radiological methods (CT and MRI). Forty-seven patients were women and average age was 58 years. Type II of edema degree was predominant (38.7%). Twenty-nine patients had parasagital meningiomas and 40 presented convexity tumors. Simpson I resection was obtained in 48 procedures, II in 18 and III in two surgical removals. Nine cases complicated (transitory deficits, 6; permanent deficit, 1; and infection, 2). Death occurred in two patients. Morbity and mortality had relation with age, falx tumors and attempt of radical surgical removal. Edema degree did not modify mortality and morbidity rates.

Carcinoembryonic antigen production associated with an osteolytic meningioma. Case report

An elevated serum carcinoembryonic antigen (CEA) without evidence of neoplasia was noted in an 84-year-old woman. She subsequently developed a lytic skull lesion, which at surgery proved to be an atypical meningioma. Immunohistochemical analysis demonstrated that this tumor was producing CEA. This aggressive meningioma required two further resections and adjuvant radiotherapy in the following 18 months. Serum elevation of CEA has been reported only twice in association with meningiomas; both of those tumors were of the secretory subtype.

Novel eosinophilic intracytoplasmic inclusions in a meningioma

BACKGROUND

Two forms of inclusion, extracellular and intracytoplasmic, have been reported in meningiomas. The authors recently encountered a case of meningothelial meningioma with unusual round eosinophilic intracytoplasmic inclusions.

METHODS

Ultrastructural and immunohistochemical studies were performed on the surgically removed tissue.

RESULTS

Ultrastructurally, the inclusions were found in the cytoplasm and processes of the tumor cells. Each inclusion consisted of a dense central mass of filaments with a looser, less dense periphery of radiating filaments. At the periphery, crystalloid lamellar structures and granules were intermingled frequently. No limiting membrane was observed. Immunohistochemically, the inclusions were unreactive for five classes of intermediate filaments, actin, ubiquitin, and amyloid.

CONCLUSION

The intracytoplasmic inclusions were ultrastructurally distinct from those reported previously. The molecular aspect of these novel eosinophilic intracytoplasmic inclusions remained uncertain.

Secretory meningioma with elevated serum carcinoembryonic antigen level

We recently encountered a 68-year-old woman with right sphenoid wing meningioma of the secretory type accompanied by an elevated serum carcinoembryonic antigen level. This case was neuroradiologically characterized by marked brain edema. Histologically, the lesion was rated as having meningothelial components and was rich in blood vessels and pseudopsammoma bodies. Carcinoembryonic antigen, epithelial membrane antigen, keratin, and cytokeratin were immunohistochemically detected in the pseudopsammoma bodies and the cells producing these bodies.

Filamentous inclusions of unusual composition and architecture in a metastatic tumor showing myoepithelial differentiation

A hyaline/eosinophilic cytoplasmic inclusion is described in a metastatic tumor occurring in the omentum and bowel of a 32-year-old white woman. The tumor was essentially of round cell type; was positive for cytokeratin, actin, and S-100 protein by immunohistochemistry; and showed desmosomes (maculae adherentes), tonofibrils, modestly developed myofilaments with focal densities, and a basal lamina by electron microscopy. It was therefore interpreted as showing myoepithelial differentiation. Nearly all cells possessed a large, rounded cytoplasmic inclusion that was architecturally unusual, consisting of intermediate filaments intermingled with lattices of fine filaments. The inclusions exhibited an additionally unusual immunohistochemical staining for both cytokeratin and actin. A comparison with cases described in the literature is made.

Incidence and clinicopathological features of meningioma

The incidence of intracranial meningioma in Manitoba, Canada, was reviewed from 1980 through 1987. During that time, 193 tumors were diagnosed, with a male:female ratio of 1:2. This occurrence corresponded to crude incidence rates of 2.3/100,000 for all meningiomas and 0.17/100,000 for malignant meningiomas. Among malignant meningiomas, the male:female ratio was 1:1. The age-specific annual incidence rate increased with age up to the eighth decade where it peaked at 8.4/100,000. The distribution of histopathological subtypes was: 74 meningotheliomatous (38%), 64 transitional (33%), 14 malignant (7%), 14 fibroblastic (7%), seven psammomatous (4%), four angioblastic (2%), and 16 unknown (8%). The diagnosis of malignant meningioma was based on the World Health Organization criteria, with only Grade III and IV tumors included in this subtype. Clinical features did not allow for differentiation of benign from malignant neoplasms. Individuals with malignant tumors were, however, more likely to suffer paresis (50%) and less likely to be without deficit (14%) than their benign counterparts. The radiographic appearance of "mushrooming" was observed only in patients with malignant meningioma. All malignant tumors showed evidence of peritumoral edema; however, none exhibited calcification. During the 8-year study interval, the tumor recurred in 10 (71%) of the 14 patients with malignant meningioma. Tumor recurrence was accompanied by dedifferentiation from a more benign histology in four patients (2% of the total material).