The Clinical Features And Pathogenetic Mechanisms Of Meningiomas With Hemorrhagic Onset

Part1 The clinical analysis of meningiomas with hemorrhagic onsetObjective:Meningiomas are the most common benign intracranial tumors and often grow slowly.They usually present with symptoms such as headache,dizziness,limb weakness,seizures,and gradually progressing neurological deficits;however,the clinical presentation of spontaneous hemorrhage is rare in these tumors.Although uncommon,gross intracranial hemorrhage of meningiomas could have a dramatic effect on outcomes and may even be a life-threatening event due to acute increased intracranial pressure.In addition,most patients did not find coexistence with meningiomas before the hemorrhagic event,meningiomas with hemorrhagic onset can be the first clinical manifestation.Thus,it is the key point of early diagnosis and correct treatment to improve their outcomes.Through collecting patients’ clinical data and by contrast with the patients with non-hemorrhagic meningiomas,the aim of this part is to characterize their clinical features and to identify the possible risk factors for the x spontaneous hemorrhage from meningiomas.Methods:Four hundred and ninety-seven cases of meningiomas between March,2008 and March,2017 from neurosurgical department of our hospital were reviewed,15 patients were diagnosed as meningiomas with hemorrhagic onset by imaging,operation,or histopathology.Data on demography,clinical presentation,radiological results,pathological outcomes,treatment,postoperative complications,and follow-up were analyzed.45 cases with non-hemorrhagic meningiomas were chosen randomly in the same period and served as a comparison group.The above data between these two groups(hemorrhagic group and non-hemorrhagic group)were compared to find their difference and the possible bleeding propensity indexes of the meningiomas.Statistical analysis was performed by the SPSS 11.0 software package.All continuous data are expressed as mean±standard deviation.Differences among groups were analyzed by using Student’s t test and Chi-squared test,and differences were considered significant at P<0.05.Results:1.Clinical presentations and radiological resultsAll hemorrhagic meningioma patients experienced a stroke-like episode characterized by the sudden onset of acute headache,nausea and vomiting,vertigo,epileptic seizures,hemiparesis,and/or altered consciousness.Hemorrhagic symptom was the first clinical presentation for most patients in hemorrhagic group.Computed tomography(CT)and magnetic resonance imaging(MRI)displayed well-defined,dense,contoured extra-axial masses displacing the adjacent brain and acute or subacute hemorrhage.There were three bleeding types including pure intratumoral hemorrhage,pure extratumoral hemorrhage,and mixed hemorrhage.On MRI with gadolinium enhancement,the mass with a dural base showed moderate to strong enhancement except for the portion representing hemorrhage.Hemorrhagic meningiomas usually had significant peritumoral brain edema(PTBE)comparing with non-hemorrhagic meningiomas.In addition,abnormal blood vessels,such as aneurysms or arteriovenous malformations,were not detected on CT angiography.2.Relation of hemorrhagic meningiomas to age and sexThe averages of hemorrhagic group and non-hemorrhagic group were 56.3± 10.6 years old and 53.2±11.5 years old respectively.There was no statistical difference between these two groups.There were 6 men and 9 women in hemorrhagic group,and the other group had 17 men and 28 women.The difference was also not statistically significant(P>0.05).3.Relation of hemorrhagic meningiomas to clinical factorsSuch clinical factors associated with brain hemorrhage,involving hypertension,diabetes,a recent history of head trauma and operation,a medical history of anticoagulant and antiplatelet therapy,pregnancy,radiotherapy history and so on,had no statistical difference between the two groups(P>0.05).4.Relation of hemorrhagic meningiomas to radiological resultsThe hemorrhagic meningiomas were located on the convexity(n=8),parasaitial areas(n=3),skull base(n=2),falx(n=1),and cerebellopontine angle(n=1).Although parasaitial areas is the most common site for meningiomas,however,meningiomas located on the convexity had an increased propensity for spontaneous bleeding.MR examination was performed in 13 patients in hemorrhagic group and the dural tail sign was assessed on Gd-enhanced T1WI.The dural tail sign could be observed in 53.8%of these patients(7/13)and the mean length of dural tail was 3.3±1.3 cm.The incidence and mean length of dural tail were 62.2%(28/45)and 4.2±2.8 cm in non-hemorrhagic group.There were no significant difference of the incidence and mean length of dural tail between the two groups(P>0.05).The mean maximum diameter of hemorrhagic meningiomas was 5.3±2.7cm which was higher than that in non-hemorrhagic group(4.7±3.3cm),but the difference was not significant(P>0.05).PTBE occurred 86.7%(13/15)of patients in hemorrhagic group and the edema index(El)was 3.5±2.1.The incidence rate of PTBE was 51.1%(23/45)and EI was 2.2±1.3 in the non-hemorrhagic group,which were statistically lower than those in the hemorrhagic group(P<0.05).5.Relation of hemorrhagic meningiomas to histopathological typeHistologically,the tumors were subtyped as meningothelial(3 cases),microcystic(2 cases),atypical(2 cases),fibrous(2 cases),angiomatous(2 cases),secretory(1 cases),transitional(1 cases),psammomatous(1 cases),and malignant(1 cases).According to the 2007 WHO classification criteria of pathological grading,12 cases were WHO Grade I tumors,2 cases were WHO Grade II tumors,and 1 case was WHO Grade III tumor.Most histopathological types of meningiomas could occur spontaneous hemorrhage,and the pathological grading in hemorrhagic group had also not significant difference comparing with that in non-hemorrhagic group.6.Surgical resection and tumor recurrence in hemorrhagic meningiomasThe degree of surgical resection was classified according to Simpson classification criteria.Simpson classification in hemorrhagic group was classified as Grade Ⅰ 60%,Grade II 13.3%,Grade III 20%,and Grade IV 6.7%,which was not statistically different from that in non-hemorrhagic group(Grade Ⅰ 46.7%,Grade Ⅱ 24.4%,GradeⅢ 20%,and Grade IV 8.9%,P>0.05).In addition,only 1 patient(6.7%)with tumor recurrence was found in hemorrhagic group and there were 4 patients(8.9%)in non-hemorrhagic group.The difference of tumor recurrence between the two groups was not significant.7.Relation of hemorrhagic meningiomas to pial arteriesIn hemorrhagic group,cerebral-pial supply of meningioma and proliferation of peritumoral pial arteries were found during operation in 12 patients(80%)and 10 patients(66.7%)respectively.35 patients(77.8%)and 11 patients(24.4%)in non-hemorrhagic group had cerebral-pial supply and proliferation of peritumoral pial arteries respectively.It was interesting that cerebral-pial supply had not significant difference between the two groups(P>0.05);however,the rate of proliferation of peritumoral pial arteries was statistically different between these two groups(P<0.05).8.Relation of hemorrhagic meningiomas to complications and prognosisAmount of bleeding during operation,postoperative hemorrhage,postoperative stroke,epilepsy,significant brain edema,and intracranial infection were assessed after surgery.All the cases were evaluated by GOS 6 months after surgery.There were no significant difference(P>0.05)in common complications and prognosis after surgery through the contrast of hemorrhagic group with non-hemorrhagic group.Conclusions:Meningiomas are benign,slow-growing,and highly vascularized tumors;it is unusual that their occurrence is spontaneous hemorrhage.All patients with hemorrhagic meningiomas could experience a stoke-like symptom by the sudden onset of acute headache,nausea and vomiting,vertigo,epileptic seizures,hemiparesis,and/or altered consciousness.Gross intracranial hemorrhage of meningiomas may play a disastrous effect on outcomes;however,these patients could gain good outcomes when the early diagnosis and correct treatment were carried.Examinations of CT and enhanced MRI are very useful for the diagnosis of meningiomas with hemorrhagic onset.Extra-axial mass,tumor-associated hemorrhage,and significant PTBE are the three important features of bleeding meningiomas in neuroimaging.In addition,there are three bleeding types including pure intratumoral hemorrhage,pure extratumoral hemorrhage,and combined intra/extratumoral hemorrhage.Most histopathological types and all the pathological grading of meningiomas could occur spontaneous hemorrhage.Increased bleeding tendency was found to only be associated with the location of tumor,PTBE,and the proliferation of peritumoral pial arteries.The other clinical bleeding propensity index of meningiomas was not found.The pathogenetic mechanisms underlying the bleeding of meningiomas remain unclear;therefore,a more complete understanding of this hemorrhagic condition is needed.Part 2 The pathogenetic mechanisms underlying meningiomas with hemorrhagic onsetObjective:Meningiomas are most often slow-growing intracranial benign tumors and usually present with symptoms as headache,dizziness,seizures,and gradually progressing neurological deficits;however,the clinical presentation of spontaneous hemorrhage is uncommon in these tumors.Although this condition is unusual,gross intracranial hemorrhage from meningiomas could have a dramatic effect on outcomes and may even be a life-threatening event due to acute increased intracranial pressure.Bleeding in malignant tumors generally result from weakness of the neoplastic vessels,infiltration of tumor cells into the vessel,and tendency of the mural endothelium to proliferate,which lead to vessel destruction and necrosis;however,the pathophysiological mechanisms underlying the bleeding from meningiomas remains unclear.In the clinical study of part Ⅰ,increased bleeding tendency was found to be associated with the location of tumor,PTBE,and proliferation of peritumoral pial arteries.In this section of part Ⅱ,a more complete understanding of pathogenetic mechanisms underlying the hemorrhagic condition in meningiomas was further identified.Methods:A series of 497 surgically removed meningiomas had been collected from patients undergoing craniotomy surgery from 2008.3 to 2017.3,15 hemorrhagic tissues were obtained and 18 non-hemorrhagic tissues from above meningiomas were randomly pick out.The experimental tissues included fresh tissue get from operation then preserved in ultra-low temperature freezer and paraffin block tissues filed by pathobiology department.These chosen tissues were divided into three groups:intratumoral hemorrhage group(n=9),extratumoral hemorrhage group(n=6),and non-hemorrhagic group(n=18).Factors,having close correlation with tumor cell proliferation,apoptosis,invasion,angiogenesis,and PTBE such as CD31、CD34、SMA、VEGF、HIF-1α、MMP-9、Ki-67 were selected to be tested by hematoxylin and eosin(HE)staining,immunohistochemistry,Western bloting(WB),and Tunel staining in these groups.The above experimental results were compared to find out their different expression among the three groups.These protein expression levels,proliferation index,and apoptosis rate were further made correlation analysis with PTBE and proliferation of peritumoral pial arteries to provide information for clarifying the pathogenetic mechanisms of hemorrhagic onset.Statistical analysis was performed by the SPSS 11.0 software package.All continuous data are expressed as mean±standard deviation.Student’s t test or One-Way ANOVA was used in comparison between measurement data groups,and Chi-squared test was used in comparison between enumeration data groups.Spearman’s or Pearson’s correlation analysis was used to analyze the correlations among associated factors.Differences were considered significant at P<0.05.Results:1.Two distinct types of blood vessels in meningiomasOf all the vasculature in meningiomas revealed by anti-CD31 antibody staining,most vessels could be also stained by anti-CD34 antibody;however,some blood vessels were stained only by anti-CD31.Thus,there are two distinct types blood vessels in meningiomas:undifferentiated vessel(CD31+/CD34-)and differentiated vessel(CD31+/CD34+).Through staining for the marker of SMA,the pericyte coverage of above different tumor vessels was further assessed and experimental results showed that differentiated vessels were frequently surrounded by pericytes,whereas undifferentiated vessels had few surrounding pericytes.2.Different amounts of tumor vessels in different groupsThe vascular density of differentiated vessels was determined as the CD34+ vessel count,and the number of undifferentiated vessels was obtained by subtracting the CD34+ vessel count from the CD31+vessels count.The mean number of CD31+vessels in intratumoral hemorrhage group,extratumoral hemorrhage group,and non-hemorrhagic group was 66.2±15.5,69.1±14.3,and 63.7±17.1 respectively.There was no significant difference among three groups(P>0.05);the mean number of differentiated vessels intratumoral hemorrhage group is 42.6±13.9,compared with 39.8±12.3 in extratumoral hemorrhage group and 51.8±14.8 in non-hemorrhagic group,there was also no significant difference(P>0.05);the mean numbers of undifferentiated vessels in intratumoral hemorrhage group(23.7±5.1)and extratumoral hemorrhage group(29.6±6.9)were both significantly higher than that in non-hemorrhagic group(13.2±3.4)(P<0.05).However,the difference between the two hemorrhagic groups was not statistically significant(P>0.05).3.Expression levels of VEGF,HIF-1α,and MMP-9 proteins among groupsWB showed that all the tissues in three groups could express VEGF protein and expression levels of VEGF in intratumoral hemorrhage group and extratumoral hemorrhage group were both significantly higher than that in non-hemorrhagic group(P<0.05).However,there was no significant difference between the two hemorrhagic groups(P>0.05).In addition,the expression levels of HIF-1α and MMP-9 proteins were low in all groups and displayed no significant difference among the three groups(P>0.05).4.The relationship between VEGF protein and clinical factorsThe above Part I and Part II results had showed that increased bleeding tendency was found to be associated with the undifferentiated vessels,PTBE,and proliferation of peritumoral pial arteries.Pearson’s analysis further showed that there was a significant association between the expression level of VEGF protein and the amount of undifferentiated vessels(P<0.05).In addition,the significant correlation was also found between the expression level of VEGF protein and EI.The expression level of VEGF protein also had significant correlations with PTBE and proliferation of peritumoral pial arteries by the Spearman’s analysis(P<0.05).The other significant relationships were not found between VEGF protein and other clinical factors(P>0.05).5.The proliferation and apoptosis of tumor cells in different groupsKi-67 expression by Immunohistochemical method and apoptosis by Tunel staining showed low level in all groups.Neither the labelling index of Ki-67 nor the apoptosis index had significant difference among the three groups(P>0.05).Conclusions:The tumoral vasculature in meningiomas is heterogeneous,and there are two distinct types of blood vessels including differentiated vessel and undifferentiated vessel.The morphological characteristics of undifferentiated vessel included absent or small lumen,no or less pericyte coverage,a thinner vessel wall,and smaller size in contrast with differentiated vessel.So undifferentiated vessels contribute to a fragile state of tumor vasculature that can be disrupted by a precipitating event,thus directly leading to spontaneous hemorrhage from meningiomas in certain conditions.VEGF protein showed higher expression level in the two hemorrhagic groups than that in non-hemorrhagic group.The higher expression of VEGF protein could induce proliferation of undifferentiated vessels and may play an indirect role in the hemorrhagic onset in meningiomas.Meanwhile,VEGF protein high expression also promotes the formation of meningioma PTBE and proliferation of peritumoral pial arteries.Thus,the PTBE could be served as a neuroimaging marker of bleeding propensity in meningiomas.The expression of VEGF protein is closely associated with HIF-1α and MMP-9 protein in most tumors;however,their correlations among them were not found in meningiomas and the expression of VEGF protein in meningiomas was induced by other factors.In addition,the proliferation and apoptosis of tumor cells may play no significant role in the spontaneous hemorrhage from meningiomas.In sum,VEGF protein cannot alone reliably account for all the spontaneous hemorrhage in meningiomas,but that play an important role in the hemorrhagic onset of meningiomas.