Ki‐67 proliferative index predicts clinical outcome in patients with atypical or anaplastic meningioma

Meningiomas represent the second most common central nervous system neoplasms in adults and account for 26% of all primary brain tumors. Although most are benign, between 5% and 15% of meningiomas are atypical (grade II) whereas 1–2% are anaplastic meningiomas (grade III). Although histological grade is the most relevant prognostic factor, there are some unusual cases in which establishing a diagnosis of high‐grade meningioma following 2000 World Health Organization (WHO) histological criteria is extremely difficult. Therefore, the aim of the present study was to evaluate the predictive value of Ki‐67 labeling index and its contribution to current WHO classification in predicting tumor recurrence and overall survival in patients with high‐grade meningiomas. A total of 28 patients (with 16 atypical meningiomas and 12 anaplastic meningiomas) were evaluated for demographic, clinical, radiological and therapeutic variables, and for Ki‐67 immunohistochemistry. Median Ki‐67 labeling index in the whole series was 7.0 (0.5–31.5) with no differences with respect to the histological grade (P = 0.87). In the univariate analysis, Ki‐67 labeling index and postoperative Karnofsky performance status were identified as significant prognostic factors of tumor recurrence and overall survival. The multivariate analysis demonstrated that Ki‐67 labeling index is the only independent predictor of both tumor recurrence and overall survival. More importantly, this predictive value was maintained in both patients with atypical and patients with anaplastic meningioma.     

Clinical Implications of the Mitotic Index as a Predictive Factor for Malignant Transformation of Atypical Meningiomas

ObjectiveIntracranial atypical meningiomas have a poor prognosis and high rates of recurrence. Moreover, up to one-third of the recurrences undergo high-grade transformation into malignant meningiomas. We aimed to investigate the clinical factors that can predict the propensity of malignant transformation from atypical to anaplastic meningiomas. MethodsBetween 2001 and 2018, all patients with atypical meningioma, in whom the tumors had undergone malignant transformation to anaplastic meningioma, were included. The patients’ medical records documenting the diagnosis of atypical meningioma prior to malignant transformation were reviewed to identify the predictors of transformation. The control group comprised 56 patients with atypical meningiomas who were first diagnosed between January 2017 and December 2018 and had no malignant transformation. ResultsNine patients in whom the atypical meningiomas underwent malignant transformation were included. The median time interval from diagnosis of atypical meningioma to malignant transformation was 19 months (range, 7–78). The study group showed a significant difference in heterogeneous enhancement (77.8% vs. 33.9%), bone invasion (55.6% vs. 12.5%), mitotic index (MI; 14.8±4.9 vs. 3.5±3.9), and Ki-67 index (20.7±13.9 vs. 9.5±7.1) compared with the control group. In multivariate analysis, increased MI (odds ratio, 1.436; 95% confidence interval, 1.127–1.900; p=0.004) was the only significant factor for predicting malignant transformation. ConclusionAn increased MI within atypical meningiomas might be used as a predictor of malignant transformation. Tumors at high risk for malignant transformation might require more attentive surveillance and management than other atypical meningiomas.     

Atypical (anaplastic) meningioma: relationship between histologic features and recurrence--a clinicopathologic study

Two-hundred-and-eighty meningiomas of the surgical pathological files of the Taipei Veterans General Hospital from the period 1976-1986 were reviewed by the authors without prior knowledge of clinical circumstances or outcome. Thirty-four cases were regarded as atypical or anaplastic based on high cellularity, pleomorphism and the presence of mitotic figures with 6 cases showing only the above features and the remaining 28 displaying in addition one or more of the following "ominous" variables: papillary formation, necrosis and invasion of the underlying brain. With a median follow-up of three years after surgery the recurrence rate was 44% (15 cases) for this group of tumors whereas the remaining 246 histologically benign meningiomas had a 6% recurrence rate during the same period. This difference was statistically significant (p less than 0.0001). Once the atypical or anaplastic character of a meningioma was established, no difference in the recurrence rate was found related to the number of mitoses and whether the additional ominous variables were present, alone or in conjunction with others. Immunostaining for vimentin, S100, fibronectin and EMA showed variable results in the 34 atypical meningiomas but without significant difference between those that recurred within 3 years and the ones that did not.     

Anaplastic meningioma: Progression from atypical and chordoid morphotype with morphologic spectral variation at recurrence

The current WHO 2007 classification divides meningiomas into a 3‐grade prognostic hierarchy. Recent literature evokes two pathways to disease progression in meningiomas akin to a comparable paradigm in gliomas, but without similar prognostic connotation: de novo anaplastic meningioma (better prognosis), and transformed meningioma (worse prognosis). We present two adult cases of transformed meningiomas that display a spectrum of morphologic progression. Case 1 at presentation showed a random admixture of meningothelial, atypical and anaplastic meningioma. The tumor recurred as anaplastic meningioma. Case 2 presented as a chordoid meningioma, but recurred as anaplastic meningioma mainly at the invasive front in transition with residual chordoid pattern. Of interest, portions of tumor also showed papillary configuration. In accordance with the dire prognosis for anaplastic meningioma, both patients succumbed to their disease within 2 months of recurrence. The present study highlights two main points: First, that proper recognition of focal high‐grade areas in a heterogeneous low‐grade meningioma (case 1) provides critical morphologic clues to spatial histologic progression and predicts aggressive biologic behavior, as evidenced by progression to frankly anaplastic meningioma at recurrence. Second, the presence of papillary in addition to anaplastic areas, in the recurrence of a previously diagnosed chordoid meningioma supports the ostensibly heightened transforming potential of grade II meningiomas, but also reflects on the morphologic heterogeneity of high‐grade meningiomas, and their potentially diverse pathways of progression. We propose that grading of meningiomas as outlined by WHO is of more critical prognostic import than histologic sub‐typing, and must include a thorough survey of the tumor‐brain interface. Future molecular genetic correlates, akin to those characterized in gliomas, could help stratify prognostic subcategories to refine meningioma grading, and govern optimal therapeutic strategies.     

非典型性脑膜瘤与良性脑膜瘤MRI征象的对比分析

目的 对比分析非典型性脑膜瘤与良性脑膜瘤的MRI征象特点,提高对非典型性脑膜瘤的认识。方法 回顾性分析经病理证实的37例非典型性脑膜瘤与288例良性脑膜瘤的MRI征象。结果 非典型性脑膜瘤直径>6.5 cm比例、肿瘤呈分叶型比例、瘤脑界面不清晰比例、重度瘤周水肿比例、邻近骨质改变比例均明显高于良性脑膜瘤（P<0.05）。多因素Logistic回归分析显示,肿瘤较大及瘤脑界面不清晰为非典型性脑膜瘤的可能性显著增加,肿瘤大小每增加1.5 cm,非典型性脑膜瘤的概率是良性脑膜瘤的1.507倍,瘤脑界面不清晰为非典型性脑膜瘤的概率是良性脑膜瘤的2.605倍。结论 肿瘤大小及瘤脑界面对于非典型性脑膜瘤与良性脑膜瘤的鉴别诊断具有重要价值。     

E-钙粘素和β-连环素在脑膜瘤中的表达及意义

Objective To analyze the expressions of E-cadherin and β-catenin in meningioma by immunohistochemistry for further understanding of biological behaviors of meningiomas. Methods The specimens included in this study were collected form 49 meningioma cases. EnVision was used in immunohistochemieal staining. The results were graded depending on the positive rate and intensity of the immunoreactivity. E-cadherin and β-catenin in meningiomas were analyzed in relationship with WHO2000 grading and invasion. Results The positive rates of E-adhesion in meningioma WHO Ⅰ,Ⅱ,Ⅲ were 92.69%, 33.33% and 0, respectively (P<0.05). The positive rates of β-catenin in meningioma WHO Ⅰ,Ⅱ,Ⅲ were 82.93%, 33.33% and 20.00%, respectively (P<0.05). The positive rate of E-adhesion in meningiomas without invasion (94.12%) was higher than that in ones with invasion (46.67%), and the difference was of statistical significance (P<0.05). The difference in positive rate of β-catenin was statically significant between meningiomas without invasion (88.24%) and the ones with invasion (33.33%, P<0.05). Conclusions The levels of E-adhesion and β-catenin are in close correlations with the WHO2000 grading of meningioma. In the atypical or anaplastic meningiomas, the expressions of E-adhesion and β-catenin are lower significantly. The levels of E-adhesion and β-catenin are also in close correlations with the aggressiveness of meningioma. The lower the expressions of E-adhesion and β-catenin, the more invasive meningioma will possibly be.     

脑膜瘤生物学特性与MRI信号特征的相关性研究

目的探讨脑膜瘤手术前MRI信号特征对手术中肿瘤生物学特性的预测价值。方法以WHO 2000年脑膜瘤病理分类为基础，追踪研究85例脑膜瘤患者，寻找肿瘤MRI信号特征与生物学特性，包括供血、质地以及瘤一脑界面是否清楚及其内在联系。结果不同病理亚型的脑膜瘤，表现出不同的MRI信号特征和生物学特性。多数良性脑膜瘤MRI信号均匀、形态规则，肿瘤周围水肿由肿瘤生长部位决定。非典型脑膜瘤MRI信号不均匀、形态不规则，肿瘤周围水肿不明显，间变型脑膜瘤周围水肿则非常明显。血管瘤型、间变型和部分非典型脑膜瘤血供丰富。微囊型、多数上皮型和多数血管瘤型脑膜瘤质地偏软，纤维型、化生型和砂粒体型则质地偏韧、硬。间变型、部分非典型和部分血管瘤型脑膜瘤的瘤一脑界面不清楚。结论脑膜瘤MRI信号特征的分析能为判断其病理亚型和生物学特性提供线索，有助于临床上制定手术策略，提高疗效。     

MMP-9、TIMP-1及其mRNA在脑膜瘤中的表达

目的探讨基质金属蛋白酶-9（MMP-9）、MMP-1组织抑制剂（TIMP-1）以及MMP-9 mRNA、TIMP-1 mRNA在脑膜瘤中的表达及其与脑膜瘤侵袭性的关系。方法采用免疫组化技术法测定手术切除的70例不同组织学类型脑膜瘤标本中MMP-9及TIMP-1的蛋白表达，并用原位杂交技术检测在不同组织类型脑膜瘤中MMP-9、TIMP-1基因在转录水平的表达，并测量其吸光度比值进行对比。结果MMP-9和TIMP-1在良性脑膜瘤中的阳性表达率分别为35.00％和52.50％，在恶性脑膜瘤中的阳性表达率分别为76.67％和53.33％。MMP-9在恶性脑膜瘤和良性脑膜瘤中的表达存在显著性差异（P〈0.05），而TIMP-1在二者之间差异无显著性（P〉0.05），但MMP-9 mRNA及TIMP-1 mRNA的表达在不同组织学类型脑膜瘤中存在显著性差异（P〈0.05）。结论MMP-9与脑膜瘤的生物学特性相关，促进脑膜瘤的侵袭性生长，其表达在基因转录水平已经上调，MMP-9和TIMP-1表达的失衡与脑膜瘤的恶性程度和侵袭能力相关，MMP-9、TIMP-1基因参与了脑膜瘤的发展过程，与脑膜瘤的生物学行为有关。     

High-dose radiation-induced meningiomas following acute lymphoblastic leukemia in children

The authors review three personal cases of patients who developed cerebral meningiomas following high-dose radiotherapy for acute lymphoblastic leukemia. Two patients were female and one male. Their ages when the leukemia appeared were between 11 and 15 years. All patients were treated with a course of prophylactic irradiation to the neuraxis for a total dose of 24 Gy. After an average interval of 10.4 years, all three patients presented a meningioma; histologically, one was meningothelial and two were fibrous. All three meningiomas presented atypical features. At follow-up 1, 4, and 4 years respectively after surgery, none of these patients presents neurological deficits or neuroradiological signs of recurrence. Forty-nine cases of high-dose radiation-induced meningioma are also reviewed.     

Falx Meningiomas: Surgical Results and Lessons Learned from 68 Cases

Objective

The purpose of this study was to review the characteristics of falcine meningioma retrospectively and to identify the parameters associated with tumor recurrence.

Methods

The analysis included; age, sex, extent of resection, and radiologic and pathologic findings. Falcine meningiomas were classified by location as anterior, middle, or posterior as described for parasagittal meningiomas.

Results

Of the 795 meningioma patients treated between 1990 and 2004 at the authors'' institution, 68 patients with meningiomas arising from the falx underwent craniotomies. There were 22 male and 46 female patients (1 : 2.1). Mean age was 55 years and ranged from 14 to 77 years. Locations of falcine meningioma were; the anterior third in 33 cases, middle in 20, and posterior in 15. Mean tumor volume was 42 cc and ranged from 4 to 140 cc. In 58 of the 68 patients tumors were totally removed. Additional surgery for recurrence was performed in 6 patients over 15 years. Of these 6 patients, only two patients underwent gross total tumor resection at first operation; the other four underwent subtotal tumor resection. Based on pathologic reports, the largest tumor subtype was transitional. There were four patients with a high grade tumor-three atypical and one anaplastic meningioma. Of the 68 patients, 59 achieved a good outcome (no neurological deficit or recurrence), six had temporary complications, two suffered new permanent postoperative deficits, and the remaining one died due to severe brain swelling despite postoperative intensive care. Extent of surgical resection was found to be significantly related to tumor recurrence.

Conclusion

Falcine meningioma accounted for 8.5% of intracranial meningiomas and the transitional meningioma was the most common subtype of falcine meningioma. Gross total resection of tumor was the single most important predictor of an improved surgical outcome.     

Two cases of atypical meningioma with pulmonary metastases: A comparative cytogenetic analysis of chromosomes 1p and 22 and a review of the literature

We present two cases of atypical meningioma WHO grade II with a history of multiple local recurrences and late pulmonary metastases. Comparative cytogenetic analyses on 1p and 22q confirmed clonal origin of the primary intracranial meningiomas and the pulmonary metastases in both cases. These cases illustrate the importance of close neuroradiological follow‐up to detect tumor recurrence in patients with atypical meningiomas WHO grade II even with clinically stable disease and should sensitize clinicians to late extracranial metastases of these tumors, especially to the lung. In an effort to elucidate common clinical features of metastatic meningiomas, especially to the lung, the literature was reviewed from 1995 to 2014, identifying a total of 45 published cases.     

脑膜瘤复发因素的术前评估及对策

目的 探讨脑膜瘤复发的相关因素，做到术前预测，为选择合适术式提供依据。方法 对125例脑膜瘤患的术前CT／MRI等影像学资料进行回顾性研究，将可能影响脑膜瘤复发的相关因素进行统计学分析，发现其中规律。结果 脑膜瘤的密度、形状与复发密切相关。结论 密度不均匀且较低、界限不清伴瘤周水肿的脑膜瘤及扁平形脑膜瘤明显易复发；肿瘤附着点处硬膜的广泛切除是防止脑膜瘤复发的关键。     

Gain of chromosome arm 1q in atypical meningioma correlates with shorter progression-free survival

M. Jansen, G. Mohapatra, R. A. Betensky, C. Keohane and D. N. Louis (2012) Neuropathology and Applied Neurobiology 38, 213–219 Gain of chromosome arm 1q in atypical meningioma correlates with shorter progression‐free survival Aims: Atypical (World Health Organization grade II) meningiomas have moderately high recurrence rates; even for completely resected tumours, approximately one‐third will recur. Post‐operative radiotherapy may aid local control and improve survival, but carries the risk of side effects. More accurate prediction of recurrence risk is therefore needed for patients with atypical meningioma. Previously, we used high‐resolution array comparative genomic hybridization to identify genetic variations in 47 primary atypical meningiomas and found that approximately 60% of tumours show gain of 1q at 1q25.1 and 1q25.3 to 1q32.1 and that 1q gain appeared to correlate with shorter progression‐free survival. This study aimed to validate and extend these findings in an independent sample. Methods: Eighty‐six completely resected atypical meningiomas (with 25 recurrences) from two neurosurgical centres in Ireland were identified and clinical follow‐up was obtained. Utilizing a dual‐colour interphase fluorescence in situ hybridization assay, 1q gain was assessed using Bacterial Artificial Chromosome probes directed against 1q25.1 and 1q32.1. Results: The results confirm the high prevalence of 1q gain at these loci in atypical meningiomas. We further show that gain at 1q32.1 and age each correlate with progression‐free survival in patients who have undergone complete surgical resection of atypical meningiomas. Conclusions: These independent findings suggest that assessment of 1q copy number status can add clinically useful information for the management of patients with atypical meningiomas.     

Clinical and histopathological analysis of proliferative potentials of recurrent and non-recurrent meningiomas

Proliferative potentials of meningiomas from 127 patients were examined immunohistochemically using the anti-Ki-67 monoclonal antibody, MIB-1, on paraffin sections, and the correlation among MIB-1 staining index (SI), histopathological finding, and clinial course of the disease was analyzed retrospectively. The mean MIB-1 SI of 50 male patients with meningioma was 5.5%, whereas that of 77 female patients was 2.7%. Higher MIB-1 SI were observed for younger patients. These age- and sex-related differences in MIB-1 SI were statistically significant. The patients were assigned to one of three groups: those with non-recurrent meningioma (n = 73); those with recurrent meningioma in whom the specimens obtained during the initial surgery were used to calculate the MIB-1 SI (n = 21); and those with recurrent meningioma for whom the specimens obtained during the surgery for recurrent tumors were used to calculate the MIB-1 SI (n = 33). The mean MIB-1 SI in these patients were 1.6%, 3.6%, and 8.8%, respectively, and there were statistically significant differences among these three groups. Statistical analyses reveal that meningiomas with a MIB-1 SI of 3% or more have a significantly high tendency for recurrence during the clinical courses, especially within the first 10-year follow-up periods. Moreover, there is statistically significant correlation between MIB-1 SI and recurrence in each Simpson’s grade. The time interval to the next recurrence for recurrent meningiomas is associated with the proliferative potential represented by the MIB-1 SI, and a correlation equation has been proposed to predict the date of the next recurrence. Analyses on cellularity of meningiomas revealed no statistically significant difference in cellularity between non-recurrent and recurrent meningiomas. There was no statistically significant relationship between cellularity and MIB-1 SI of meningiomas. In conclusion, examination on proliferative potentials of meningiomas using MIB-1 SI is very important for biological and histopathologicl analyses and the prediction of future recurrence. Received: 21 February 1995 / Revised: 28 September 1995 / Revised, accepted: 13 November 1995     

Cytoplasmic iron deposition is associated with the expression of oxidative DNA damage marker in meningiomas

Angiomatous meningiomas are rare meningioma subtypes, which are characterized by abundant, well‐formed vessels. We encountered two cases of newly diagnosed angiomatous meningiomas exhibiting tumor cells with brown pigments, which were histochemically proven to be iron. In an attempt to understand its pathological significance, we assessed this unusual finding in representatives for each grade of meningiomas and immunoexpression of transferrin receptor (CD71) and the oxidative DNA damage marker, 8‐hydroxy‐2′‐deoxyguanosine (8‐OHdG). Iron deposition in the tumor cells was observed in 8/15 (53%) angiomatous meningioma cases, 2/6 (33%) microcystic meningiomas and 2/20 (10%) meningothelial meningiomas, which included clustered microvessels, but not in fibrous, atypical or anaplastic meningiomas (P = 0.001). Cytoplasmic CD71 expression was largely negative in angiomatous meningioma cases, but positive in meningothelial and high‐grade meningiomas, suggesting that the transferrin‐dependent iron transporter was involved in iron uptake in meningiomas. Nuclear expression of 8‐OHdG was observed in ≥50% of the tumor cells in all 15 cases of angiomatous meningioma and was associated with the presence of regressive histopathological findings, such as hyalinized vessels and cystic changes. In addition, the fraction of iron‐containing tumor cells was correlated to those expressing 8‐OHdG (P = 0.005). Our finding indicates that cytoplasmic iron deposition in tumor cells is characteristic of highly vascularized benign meningiomas and related to increased oxidative DNA damage markers.     

MIB‐1 immunolabeling: A valuable marker in prediction of benign recurring meningiomas

Histological analysis has limited value to predict biological behavior of meningiomas. We investigated the utility of cell proliferative indicator in the evaluation of histologically benign meningiomas. We selected 25 benign non‐recurrent meningiomas, 15 benign recurrent meningiomas after complete surgical resection, 30 atypical meningiomas, and 15 anaplastic meningiomas out of 384 cases studied. MIB‐1 Labeling Index was evaluated by two methods: Highest Labeling Index (HLI) and Random Labeling Index (RLI). There was no dependable histological parameter to predict recurrence among benign‐looking meningiomas. HLI had significant difference when compared with RLI in all categories. The mean MIB‐1 HLI values ± SD were 3.47 ± 2.0% for benign meningiomas, 5.08 ± 4.0% for atypical meningiomas and 11.66 ± 7.06% for anaplastic meningiomas. In comparison, the mean MIB‐1 HLI of benign non‐recurrent meningiomas were 2.66 ± 1.7% and with recurrence were 4.21 ± 2.78% (P = 0.0339). Using receiver operating characteristic, it was seen that neoplasm recurred with the MIB‐1 HLI of > 2.6 having the sensitivity of 64.6% and specificity of 68% among benign (grade I) meningiomas. MIB‐1 positive tumor cells were maximally aggregated at the periphery of excised specimen. MIB‐1 HLI, integrated with standard histopathology can provide better information about the disease biological nature in benign meningiomas.     

非典型脑膜瘤的临床分析

目的探讨非典型脑膜瘤的诊断、治疗及预后相关影响因素。方法回顾性分析2001~2011年首都医科大学附属北京天坛医院收治的89例经病理证实的非典型脑膜瘤,应用Log-rank法和Cox回归进行统计分析,并结合文献对本病的特点、治疗方法和预后进行分析。结果 89例非典型脑膜瘤中72例肿瘤全切除,40例术后行放疗;中位PFS 72.6个月(2~102个月),2年、5年PFS率为74.5%、67.5%,OS率为93.6%、89.1%。单因素分析显示,继发肿瘤、女性、肢体瘫痪、KPS80的非典型脑膜瘤患者复发的风险增加(均P0.05)。多因素分析显示,继发肿瘤、肢体瘫痪患者的复发风险增加(均P0.05),KPS≥80患者有更长的存活时间(P0.05)。结论手术全切除是改善非典型脑膜瘤患者预后的重要手段;对未全切除者,术后推荐放疗。对于全切除的非典型脑膜瘤,首发症状为偏瘫、继发肿瘤、肿瘤存在骨侵袭、肿瘤存在脑侵袭。核有丝分裂象高、MIB-1指数高的患者为高危患者,存在这些危险因素中1项及以上者,推荐术后放疗。     

Involvement of disregulated c-myc but not c-sis/PDGF in atypical and anaplastic meningiomas

We investigated the expression of c-myc and c-sis/PDGF mRNA and protein products in 20 cases of meningiomas of various grades: 10 benign, 5 atypical and 5 anaplastic meningiomas. All cases of atypical and anaplastic meningiomas were positive for c-myc protein and mRNA by immunohistochemistry and in situ hybridisation, respectively, while all 10 benign meningiomas were negative for c-myc immunostaining, with only one benign tumour positive for c-myc mRNA. Expression of PDGF-BB protein and c-sis mRNA were seen in more than 80% of the meningioma cases and was not restricted to the histological grades of meningiomas. Semiquantitative analysis showed that the frequency of c-myc immunopositive cells positively correlated with Ki-67 proliferative indices. Our findings suggest that c-myc, but not c-sis/PDGF, has some concern to the malignancy of meningiomas.     

脑膜瘤全切除术后复发的组织病理学因素分析

目的 通过对患者的年龄、性别、脑膜瘤组织学分型及分级等因素的分析,了解它们与肿瘤复发间的关系.方法 56例脑膜瘤标本分为复发组(n=30)、初发组(n=26),对全部病理标本进行组织学分级,统计学分析组织学分级与肿瘤复发之间的关系.结果 复发组上皮型17例(56.67%),纤维型7例(23.33%),两型比较,P＜0.05.复发组组织病理学分级Ⅱ级、Ⅲ级者比率显著高于初发组(P＜0.01).患者的年龄、性别2组对比差异无统计学意义(P＞0.05).结论 脑膜瘤复发在组织病理学分型上以上皮型居多,脑膜瘤组织学分级越高复发率越高.     

Clinicopathologic features and pathogenesis of melanocytic colonization in atypical meningioma

Only two prior cases of benign dendritic melanocytes colonizing a meningioma have been reported. We add a third case, describe clinicopathologic features shared by the three, and elucidate the risk factors for this very rare phenomenon. A 29 year‐old Hispanic woman presented with headache and hydrocephalus. MRI showed a lobulated enhancing pineal region mass measuring 41 mm in greatest dimension. Subtotal resection of the mass demonstrated an atypical meningioma, WHO grade II, and the patient subsequently underwent radiotherapy. She presented 4 years later with diplopia, and MRI showed an enhancing extra‐axial mass measuring 47 mm in greatest dimension and centered on the tentorial incisura. Subtotal resection showed a brain‐invasive atypical meningioma with melanocytic colonization. The previous two cases in the literature were atypical meningiomas, one of which was also brain invasive. Atypical meningiomas may be at particular risk for melanocytic colonization as they upregulate molecules known to be chemoattractants for melanocytes. We detected c‐Kit expression in a minority of the melanocytes as well as stem cell factor and basic fibroblast growth factor in the meningioma cells, suggesting that mechanisms implicated in normal melanocyte migration may be involved. In some cases, brain invasion with disruption of the leptomeningeal barrier may also facilitate migration from the subarachnoid space into the tumor. Whether there is low‐level proliferation of the dendritic melanocytes is unclear. Given that all three patients were non‐Caucasian, meningiomas in persons and/or brain regions with increased dendritic melanocytes may predispose to colonization. The age range spanned from 6 years old to 70 years old. All three patients were female. The role of gender and estrogen in the pathogenesis of this entity remains to be clarified. Whether melanocytic colonization may also occur in the more common Grade I meningiomas awaits identification of additional cases.