Haemangiopericytoma diagnosed from a metastasis 11years after surgery for "atypical meningioma"

Meningeal haemangiopericytoma (HPC) is a rare tumour often mistakenly reported as "vascular meningioma". Unlike meningiomas, HPC has a high rate of local recurrence and distant metastases, which may occur several years after initial treatment. We report a patient in whom a HPC was misdiagnosed as benign vascular meningioma and the patient discharged from follow-up. HPC was diagnosed 11 years later from biopsy of a skeletal metastasis. Histological review of the meningeal tumour confirmed the diagnosis of meningeal HPC. Meningeal HPCs resemble meningiomas clinically, radiologically and even light microscopically. As a result, they can be reported as atypical meningioma, as in this case. HPC's are more aggressive than typical meningiomas, with a high rate of recurrence and distant metastasis, often late in the course of the disease. Management of meningeal HPC differs from that of typical meningioma, with a need for post-operative radiotherapy and long-term follow-up.     

MRI of germinomas arising from the basal ganglia and thalamus

We reviewed the MRI findings of germinomas originating from the basal ganglia, thalamus or deep white matter in 13 patients with 14 germinomas, excluding those in the suprasellar or pineal regions. Ten cases were confirmed as germinomas by stereotaxic biopsy, three by partial and one by total removal of the tumour. Analysis was focussed on the location and the signal characteristic of the tumour, haemorrhage, cysts within the tumour and any other associated findings. Thirteen of the tumours were in the basal ganglia and one in the thalamus. Haemorrhage was observed in seven patients, while twelve showed multiple cysts. Associated ipsilateral cerebral hemiatrophy was seen in three patients. The signal intensity of the parenchymal germinomas was heterogeneous on T1- and T2-weighted images due to haemorrhage, cysts and solid portions. We also report the MRI findings of germinomas in an early stage in two patients. Received: 31 July 1997 Accepted: 6 January 1998     

Primary meningeal tumors in children: correlation of clinical and CT findings with histologic type and prognosis.

PURPOSE: To identify the radiologic features that might help in preoperative differentiation of the meningiomas from the remaining primary meningeal tumors, in particular the malignant tumors. METHODS: The clinical and computed tomographic features of 21 children with histologically proved primary meningeal tumors were analyzed. FINDINGS: Benign tumors (meningiomas) are more likely to occur in older children, to have longer symptom duration, and to have CT appearances similar to the "typical" adult meningioma. Atypical CT features suggest a malignant meningeal tumor, such as meningeal sarcoma, melanoma, or meningeal primitive neuroectodermal tumor. The recent identification of a new subtype of meningioma (a "sclerosing" group) is discussed. This is common in children and the CT and clinical features are similar to those seen in other meningiomas. It is frequently mistaken histologically for an intraaxial tumor, or for an atypical or malignant meningioma. These sclerosing meningiomas may also show brain invasion but despite this, in the short term, the prognosis is no different from other meningiomas. CONCLUSION: The bad reputation previously ascribed to childhood primary meningeal tumors should be confined to that small group that are malignant. Meningiomas have a more favorable outlook.     

Utility of proton MR spectroscopy in the diagnosis of radiologically atypical intracranial meningiomas

Our aim was to evaluate the usefulness of proton MR spectroscopy ((1)H MRS) in the diagnosis of radiologically atypical brain meningiomas. We studied 37 patients with intracranial meningiomas with MRI and (1)H MRS (TE 136 ms). Their spectra were quantitatively assessed and compared with those of 93 other intracranial brain neoplasms: 15 low-grade and 14 anaplastic astrocytomas, 30 glioblastomas and 34 metastases. The most characteristic features of meningiomas were the presence of alanine, high relative concentrations of choline and glutamine/glutamate and low concentrations of creatine-containing compounds, N-acetyl-containing compounds and lipids. These resonances were assembled in algorithms for two-way differentiation between meningioma and the other tumours. The performance of the algorithms was tested in the 130 patients using the leave-one-out method, with 94% success in differentiating between meningioma and other tumour. Of the 37 meningiomas, five (14%) were thought atypical on MRI, and in only one of these, found to be malignant on histology, was a diagnosis other than meningioma suggested by the algorithm. The other four were correctly classified. We suggest that (1)H MRS provides information on intracranial meningiomas which may be useful in diagnosis of radiologically atypical cases.     

恶性脑膜瘤的MRI诊断

目的：探讨恶性脑膜瘤的MRI表现,提高其诊断准确率.方法：回顾性分析14例经手术病理证实的恶性脑膜瘤病例资料.结果：肿瘤边缘多不规则（11/14）,T1WI呈等、低信号9例,等、高信号2例,较均匀信号3例;T2WI像呈不均匀信号12例,呈较均匀信号2例;增强扫描均呈不均匀强化.结论：恶性脑膜瘤的MRI表现具有一定的特异性,但需注意和良性脑膜瘤鉴别.     

Extradural spinal meningioma: MRI

We report a case of extradural spinal meningioma with pathologically proven features of malignant transformation. The MRI findings of extradural spinal meningioma and differences in the findings from intradural meningiomas are discussed. Received: 16 August 1996 Accepted: 19 August 1996     

Intracranial meningeal melanocytoma: CT and MRI

We report the MRI and CT findings of an intracranial meningeal melanocytoma (IMM) arising from Meckel's cave and review the imaging characteristics of IMM. On CT, IMM constantly appear as well-circumscribed, isodense to slightly dense, extra-axial tumours with homogeneous contrast enhancement. This appearance is nonspecific and similar to that of meningiomas or small neuromas. On MRI, the signal of IMM is strongly related to the amount of melanin pigment: the more melanin, the more shortening of T1 and T2 relaxation times. Only when it shows as a homogeneous mass, bright on T1 and dark on T2 weighting, can a specific diagnosis of a melanin-containing tumour be made. However, this still cannot provide a distinction between IMM and malignant meningeal melanoma. Received: 31 January 1997 Accepted: 17 February 1997     

Primary choroid plexus papilloma of the cerebellopontine angle: magnetic resonance imaging, computed tomographic and angiographic appearances.

The computed tomographic, angiographic and magnetic resonance imaging (MRI) appearances of a benign primary choroid plexus papilloma of the cerebellopontine angle are reported. Although benign, this tumour showed local invasion of the petrous temporal bone and mastoid air cells. The differential diagnosis of cerebellopontine angle lesions is discussed. Papilloma is suggested by the presence of a vascular, calcified, enhancing extra-axial mass in or around the cerebellopontine angle. MRI may show evidence of high vascularity and internal haemorrhage. Differentiation from other cerebellopontine tumours, most particularly meningioma, may not be possible on radiological features.     

Primary nerve-sheath tumours of the trigeminal nerve: clinical and MRI findings

We reviewed the clinical and MRI findings in primary nerve-sheath tumours of the trigeminal nerve. We retrospectively reviewed the medical records, imaging and histological specimens of 10 patients with 11 primary tumours of the trigeminal nerve. We assessed whether tumour site, size, morphology or signal characteristics were related to symptoms and signs or histological findings. Histological proof was available for 8 of 11 tumours: six schwannomas and two plexiform neurofibromas. The other three tumours were thought to be schwannomas, because they were present in patients with neurofibromatosis type 2 and followed the course of the trigeminal nerve. Uncommon MRI appearances were observed in three schwannomas and included a large intratumoral haemorrhage, a mainly low-signal appearance on T2-weighted images and a rim-enhancing, multicystic appearance. Only four of nine schwannomas caused trigeminal nerve symptoms, including two with large cystic components, one haemorrhagic and one solid tumor. Of the five schwannomas which did not cause any trigeminal nerve symptoms, two were large. Only one of the plexiform neurofibromas caused trigeminal nerve symptoms. Additional neurological symptoms and signs, not related to the trigeminal nerve, could be attributed to the location of the tumour in three patients. Received: 30 June 1998 Accepted: 17 July 1998     

X-ray computed tomographic aspects of benign primary cerebral melanomas. Apropos of 4 cases

Benign primitive melanomas are rare tumours usually involving the leptomeninges. Four cranial localizations are reported: 2 tumours of the foramen magnum, 1 of the cerebellopontine angle and 1 supratentorial. The clinical symptomatology is variable according to the level. Slow medullary compression is frequent. One can emphasize the special and difficult problem of foramen magnum tumours that present with a very variable clinical status frequently simulating a non surgical disease of the central nervous system. The benign and primitive appearance of these tumours is evocated by the slow and favourable evolution and by the absence of extraneurologic melanotic tumour. Our purpose is essentially to emphasize the radiological and particularly the computed tomographic (CT) findings poorly described in the literature. Benign melanomas have resemblance with meningiomas: osseous or meningeal relationship, homogeneity and high density. On the other hand the angiography shows poor vascularization. One can think that a tumor simulating a meningioma by CT but not by angiography is perhaps a benign melanoma. The special problem of the radiological diagnosis of foramen magnum tumours is evocated: Computed myelography, tridimensional imaging by NMR.     

An unusual intraventricular haemangiopericytoma: MRI and spectroscopy

We present a 43-year-old woman with a tumour within the left lateral ventricle with the typical appearances of meningioma on MRI. (1)H MR spectroscopy demonstrated an increased choline peak, suggesting a malignant form of meningioma. Histologically a haemangiopericytoma was found, an exceptionally rare tumour at this site.     

Pituitary macroadenoma and diaphragma sellae meningioma: differential diagnosis on MRI

Diaphragma sellae meningiomas are unusual tumours often not distinguished from pituitary macroadenomas. Preoperative differentiation is essential, because the trans-sphenoidal approach is used for surgical removal of adenomas, while meningiomas are approached via a craniotomy. We reviewed five patients in whom a diaphragma sellae meningioma was initially diagnosed as a nonsecreting pituitary macroadenoma. MRI criteria for differential diagnosis are discussed. The main findings considered are visibility of the pituitary gland, contrast enhancement, the centre of the lesion and sellar enlargement. These criteria, applied to a blind review, allow correct identification of the tumours. Received: 10 September 1997 Accepted: 22 April 1998     

MRI of primary meningeal sarcomas in two children: differential diagnostic considerations

Meningeal sarcomas are very rare, highly aggressive tumours affecting children more frequently than adults. The clinical course and MRI of meningeal sarcomas in two cases are discussed with special regard to possible misinterpretation. In one case MRI demonstrated a circumscribed mass in contact with the meninges, with central areas of haemorrhage. In the other, a case of primary leptomeningeal sarcomatosis, several MRI examinations over the course of almost a year were unhelpful, despite severe neurological complaints. Then MRI revealed meningeal contrast enhancement all over the brain and spinal canal, together with cerebral infarcts. MRI of meningeal sarcomas has not been discussed in the literature. MRI did not permit specific diagnosis, but enabled visualisation of the extent of the tumour and/or meningeal involvement. Early histological diagnosis is indispensable for adequate treatment. Received: 16 January 1996 Accepted: 30 April 1996     

Intracranial ganglioglioma: clinicopathological and MRI findings in 16 patients

AIM: To record the clinical findings and magnetic resonance imaging (MRI) characteristics of intracranial gangliogliomas in 16 patients. MATERIALS AND METHODS: Sixteen patients were imaged using unenhanced and contrast-enhanced MRI. Eight patients underwent unenhanced CT and of these, three underwent contrast-enhanced CT. Two radiologists read the images retrospectively. The images were studied with regard to location, size, margin, signal intensity, enhancement characteristics, cystic changes, and presence of calcifications. Clinical data, such as presenting signs and symptoms, physical findings, and medical histories, were collected. Histopathological and immunohistochemical studies were performed and analysed by two pathologists. RESULTS: In 12 cases the tumours were located in one of the cerebral hemispheres; in the other cases they were located in the brainstem, cerebellum, suprasellar area or the thalamus. The tumour dimension varied from 1-7 cm, with a mean of 3.6 cm+/-1.8 cm. The MRI features of ganglioglioma in the present cohort can be divided into three patterns: cystic (n=2), cystic-solid (n=6), and solid (n=8). Solid lesions had a predilection for the temporal lobe; cystic and cystic-solid tumours had a wide anatomical distribution. Cystic lesions were significantly smaller than both cystic-solid and solid lesions (F=4.28, P<0.05). Cystic changes in the cystic-solid tumours showed one of the following patterns: those with walls showing contrast enhancement, those containing an enhancing nodule, or cysts without an obvious wall. The solid portion of cystic-solid gangliogliomas and the entire tumour in solid tumours showed homogeneous enhancement of variable degrees on T1-weighted (T1W) spin-echo (SE) images. Five tumours had mild or moderate oedema. In one patient two separate gangliogliomas were found, each lesion exhibiting different MRI features: solid and cystic-solid. One case of cortical ganglioglioma was found, causing bone erosion due to pressure. One tumour with chronic haemorrhage was found in the study. CONCLUSION: MRI features of gangliogliomas are non-specific. A ganglioglioma should be suspected when a tumour shows the following features: (1) a solid lesion located in the temporal lobes with mild or no oedema and homogeneous enhancement on SE T1W images; or (2) a small cystic lesion or cystic-solid mixed mass with a wall enhancement or a markedly enhanced nodule. We report a patient with two separate gangliogliomas and a case with bone erosion.     

脑膜血管外皮细胞瘤的影像诊断与鉴别诊断

目的 提高对脑膜血管外皮瘤的认识。资料与方法 回顾性分析经手术病理证实的4例脑膜血管外皮瘤的CT和MRI表现，并结合文献进行复习。结果 脑膜血管外皮瘤的CT和MRI表现类似脑膜瘤，但具有恶性征，无颅骨增生和硬膜强化（硬膜尾征），与脑膜瘤不同。结论 CT和MRI表现类似脑膜瘤的颅内肿瘤，具有恶性征，没有颅骨增生和硬膜强化者要考虑脑膜血管外皮瘤的可能。     

Primary malignant lymphoma of the maxillary sinus: CT and MRI

We reviewed the CT and MRI of seven patients with primary malignant lymphoma of the maxillary sinus to find if there are characteristic imaging findings suggestive of the disease. The images were analysed for appearance, size, signal, internal characteristics, extent of tumour, bone change and lymph node enlargement. In two patients, the tumour first presented with mucosal thickening. In the remaining five, the tumours were an expansile mass 4–6 cm in diameter at the time of detection. Although it was difficult to distinguish tumour from mucosa or obstructed fluid on CT, T2-weighted MRI enabled us to separate tumour from normal mucosa or fluid. In two patients, the tumours were heterogeneous. Calcification and haemorrhage were observed in one patient. Periantral soft-tissue infiltration was always present, even when tumour appeared as slight mucosal thickening. Posterior extension was seen in all patients. Permeative and lytic bone destruction accompanied most cases of periantral soft-tissue infiltration; mixed destruction and sclerosis was also observed. Mucosal thickening with periantral soft-tissue infiltration may suggest malignant lymphoma of the maxillary sinus in its early form. Various types of bone change may accompany the periantral soft-tissue infiltration. Received: 25 January 1999 Accepted: 21 July 1999     

Cystic lesions accompanying extra-axial tumours

We examined the mechanism of cyst formation in extra-axial tumours in the central nervous system (CNS). Cyst fluid, cerebrospinal fluid (CSF) and blood plasma were analysed in eight patients with nine peritumoral cysts: four with meningiomas, two with intracranial and two spinal intradural schwannomas. Measuring concentrations of various proteins [albumin, immunoglobulin G (IgG), IgA, α₂-macroglobulin and IgM] in cyst fluid, CSF and blood plasma provides insight into the state of the semipermeability of the blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier. Peritumoral cysts accompanying intra-axial brain tumours are the end result of disruption of the BBB and oedema formation. Unlike intra-axial tumours which lie embedded within nervous tissue, extra-axial tumours tend to be separated from nervous tissue by arachnoid and pia mater. High concentrations of proteins were measured in the cyst fluid, approaching blood plasma levels, suggesting a local barrier disruption, and passage across the arachnoid, pia mater and cortical/medullary layer into the CNS parenchyma, leaving the protein concentrations of CSF practically unchanged. We confirmed that very high concentrations of protein are to be found in tumour cysts, plasma proteins forming almost 90 % of the total protein in the cyst. We review current hypotheses on the pathogenesis of cysts accompanying neoplasms, particularly meningiomas and schwannomas, and conclude that the majority of proteins in cyst fluid in extra-axial, intradural meningiomas and schwannomas are plasma proteins. This provides a strong argument for pathogenesis of extra-axial intradural tumour cysts in favour of leakage of plasma proteins out of the tumour vessels into the nervous tissue. Received: 16 May 1998 Accepted: 6 February 1998     

Meningioangiomatosis: advanced imaging and pathological study of two cases

Meningioangiomatosis (MA) is a rare benign intracranial tumour of uncertain pathogenesis, with only 33 cases reported in the literature. Imaging features have been described in 21 cases, only 3 with contrast-enhanced MRI. We present two cases of MA with MRI and/or CT findings and gross, ultrastructural, and immunohistochemical characteristics. MRI is particularly helpful for establishing the origin of the lesion and its anatomical location, while CT shows calcification, if present. The pathological characteristics establish the diagnosis and underline the differences from other entities such as malignant meningioma, one of the most important differential diagnostic considerations.     

脑膜瘤影像诊断误诊分析

目的:探讨颅内影像表现不典型的脑膜瘤MRI与CT表现,分析其误诊原因,以提高脑膜瘤诊断的准确性.方法:回顾性分析经手术病理证实的术前第一诊断误诊的35例脑膜瘤相关病例,所有病例均行MRI平扫和增强扫描,21例同时行CT扫描,MRI与CT表现与手术病理相对照.结果:脑膜瘤误诊为其他肿瘤27例;其他病例误诊为脑膜瘤8例.结论:因组织学结构复杂及一些特殊部位构成了对脑膜瘤误诊的不可避免性;而注重典型MRI特征结合CT征象、仔细阅片及结合病史等,是提高诊断符合率的关键.     

恶性脑膜瘤MRI表现与病理对照研究

目的：研究ＭＲＩ诊断恶性脑膜瘤特征性表现的可靠性及限制。材料和方法：回顾性分析５０例恶性脑膜瘤的ＭＲＩ表现，与手术病理相对照，同时随机抽取同期５０例良性脑膜瘤加以比较研究。结果：５０例恶性脑膜瘤中，男女之比为１．５：１；ＭＲＩ显示恶性脑膜瘤多呈不规则形（３５／５０），轮廓常呈分叶状（１５／５０），结节状（１２／５０）和锯齿状（８／５０），包膜常不完整（２８／５０），瘤内信号多不均匀（２１／５０），造影后瘤内不均匀强化多见（２６／４０），脑膜尾征以粗短不规则为特征（９／１３），与良性组比较有统计学意义（ｘ２检验：Ｐ＜０．０５）。病灶部位、大小、边缘及瘤周水肿良、恶性者比较无统计学意义。结论：本组术前定位诊断正确率为１００％，定性诊断正确者仅１例，回顾性分析定性诊断正确率可达８６％。因此提高认识、足够重视，恶性脑膜瘤的术前定性诊断正确率将明显提高。