Parapharyngeal meningioma with special reference to cell of origin

A Case of Recurrence of Benign Convexity Primary Intraosseous Meningioma

Meningiomas originating within the bones of the skull are rare and have been reported as primary intraosseous meningiomas (PIOM). Moreover, PIOMs with a skull base location or malignant pathology are predisposed to recurrence; however, recurrence is quite rare among PIOMs characterized by a convexity location and benign pathology. Here, we present a case of extensive recurrence of a convex intraosseous meningioma with benign pathology. A 72-year-old woman presented with a headache to our hospital. Gd contrast-enhanced magnetic resonance imaging revealed an enhanced tumor in the left frontal to the parietal region extending through the calvarial bone and invading the subdural space and subcutaneous tissue. Skull radiograph and computed tomography identified a remarkable osteolytic change in the lesion. Macroscopic complete resection (MCR) of the tumor and the surrounding tissues was performed. The tumor was histopathologically diagnosed as a transitional meningioma (World Health Organization grade 1). Seven years after the surgery, the patient presented with dysarthria, and the recurrence of the tumor was identified as massive lesions extending through the calvarial bone to the orbital bone, partially protruding into the brain and scalp. MCR was performed again, with the reconstruction of the skull for an extensive calvarial area using a titanium plate. This case is unique due to the extensiveness of the recurrent tumor and its rarity. Here, we report the details of the clinical course and discuss the characteristics of this case.

Surgical Resection of Large Primary Intraosseous Meningiomas (6 Case Reports)

OBJECTIVE

The clinical features and surgical techniques related to patients undergoing resection of extracranial large primary intraosseous meningiomas are studied.

METHODS

The clinical characteristics, treatment, and prognosis of 6 patients with primary intraosseous meningiomas larger than 5 cm in diameter were retrospectively reviewed in the 10th Neurosurgical Department of Beijing Tiantan Hospital, Capital Medical University.

RESULTS

Five males and one female (18-57 years old) suffered from large primary intraosseous meningiomas. The main symptoms were headaches accompanied by head swelling. CT showed irregular thickening of the bone diploe with increased density and uneven surface. MRI showed partial bone destruction of the skull, local thickening of the internal and external plates, shell and palisade changes of the external cranial plate, and enhancement of the adjacent meninges. A horseshoe or coronary incision plus the "Mercedes-Benz" incision were chosen to expose the skull bone, and drilling was performed in the normal skull bone at the transition zone between abnormal and normal skull bone. After drilling, the sub flap dura was dissected, the hyperplastic skull was dissected with a milling cutter, and the residual tumor was then resected. A cranioplasty was performed 6 months to 1 year later.

CONCLUSIONS

Surgical treatment and precise perioperative management can achieve a better prognosis for large intraosseous meningiomas.

Primary ectopic meningioma in the thoracic cavity: A rare case report and review of the literature

Background

Meningioma is a common type of intracranial tumor in adults. It rarely arises in the chest, with only a few case reports in the English literature. Here, we report the case of a patient with a primary ectopic meningioma (PEM) located in the thoracic cavity.

Case presentation

A 55-year-old woman presented with exercise-induced asthma, chest tightness, intermittent dry cough and fatigue for several months. Computed tomography revealed the presence of a huge mass in the thoracic cavity, with no connection to the spinal canal. Lung cancer and mesothelioma were suspected, and surgery was performed. Grossly, the mass was a grayish-white solid 9.5 cm × 8.4 cm × 5.3 cm in size. The microscopic morphology of the lesion was consistent with that of typical central nervous system meningioma. The pathological subtype was transitional meningioma. The tumor cells were arranged in a fascicular, whorled, storiform and meningithelial pattern, with occasional intranuclear pseudo-inclusions and psammoma bodies. In focal areas tumor cells were considerably dense, and the cells were round or irregular in shape, with less cytoplasm, uniform nuclear chromatin, and visible nucleoli and mitoses (2/10 HPF). By immunohistochemistry, the neoplastic cells showed strong and diffuse staining with vimentin, epithelial membrane antigen and SSTR2 with variable expression of PR, ALK and S100 protein. However, the cells were negative for GFAP, SOX-10, inhibin, CD34, STAT6, smooth muscle actin, desmin, CKpan, D2-40, WT-1, CK5/6 and CD45. The highest proliferation index by Ki-67 was 15%. The abnormal expression of ALK led to the initial misdiagnosis of an inflammatory myofibroblastic tumor. After 12 months of follow-up, no disease progression was observed.

Conclusion

The presence of primary ectopic meningiomas in the thoracic cavity is extremely rare, and this tumor is easily misdiagnosed clinically. Imaging is suggested to determine the location and possible differential diagnosis, while the final diagnosis should be via pathological examination. Immunohistochemistry is crucial for disease diagnosis. Owing to our limited knowledge of PEM, its pathogenesis and tissue of origin remain unclear. Clinicians should pay close attention to such potential patients. The present case report may provide insights into the diagnosis and therapy of patients with this tumor.

Primary intraosseous meningioma with subcutaneous and dural invasion: A case report and literature review

Primary intraosseous meningiomas (PIOMs) are a rare subset of meningiomas, comprising fewer than 1% of all such tumors. Furthermore, PIOMs presenting as osteogenic lesions that invade both the dura and subcutaneous tissue are extremely rare. Unlike intracranial meningiomas, diagnosing and treating PIOMs are challenges due to their insidious clinical behavior and a lack of clear radiological diagnostic criteria. We report the case of a 60-year-old female with headache and a slightly outward protrusion of the parietal region of the skull. CT showed an osteogenic lesion in the right parietal bone. MR imaging indicated mild to moderate homogeneous enhancement with an intense dural reaction. The suggested clinical diagnosis was lymphoma, so we performed a skull biopsy, which revealed an intraosseous benign meningioma. A precise resection strategy was planned with a neuronavigation system accompanied by a one-step customized titanium mesh cranioplasty. The lesion was completely removed, and pathological analysis confirmed a meningothelial meningioma (WHO Grade I) of intraosseous layer origin invading the dura mater and subcutaneous tissue. This case highlights the need for an initial biopsy when the lesion is difficult to diagnose on imaging. Complete resection should be attempted to minimize the risk of recurrence.

Intraosseous meningioma mimicking osteosarcoma

Background

Predominantly intraosseous meningiomas are rare entities that include true primary intraosseous meningiomas (PIM), as well as meningiomas that may show extensive bone involvement, such as en plaque meningiomas. Different hypotheses have been proposed to decipher the origin of PIMs, such as ectopic arachnoid cap cell entrapment during birth or after trauma. Surgical resection is the treatment of choice of such lesions.

Case presentation

We present a case of a 65-year-old man with an enlarging mass in the parieto-occipital region that grew slowly and progressively over 13 years, following head trauma during a motor vehicle accident. One year prior to presentation, he started experiencing daily holocranial headaches and blurry vision. CT and MRI studies revealed a permeative midline calvarial lesion measuring 14 cm in greatest dimension with extensive periosteal reaction, extension into the subcutaneous soft tissues, subjacent dural thickening and intracranial extension with invasion of the superior sagittal sinus. The favored pre-operative clinical diagnosis was osteosarcoma. The abnormal calvarium was excised and histopathological examination confirmed the diagnosis of a predominantly intraosseous calvarial meningioma, WHO grade I.

Conclusions

The present case highlights the importance of histopathologic diagnosis in guiding therapeutic decisions and reiterates the necessity of considering PIM or meningiomas with extensive intraosseous component in the differential diagnosis of calvarial masses, even when imaging suggests a neoplasm with aggressive behavior, such as osteosarcoma.

Intraosseous metaplastic meningioma: A case report

Metaplastic meningioma is a rare World Health Organization Grade I meningioma subtype, accounting for 0.2%-1.6% of all meningiomas. Primary extradural meningiomas represent less than 2% of all meningiomas, with intraosseous meningioma as a subtype of primary extradural meningiomas. Herein, we report the case of a 65-year-old male presenting with headache. His computed tomography scans showed an osteolytic left parietal bone mass, and magnetic resonance imaging revealed hyperintense dots in the mass on T1-weighted images. The mass was then resected and diagnosed on histopathological examination as an intraosseous metaplastic meningioma.

A contemporary and a historical patient with an ectopic meningioma

Introduction: Ectopic meningiomas are rare tumors which can be encountered by all surgical specialties. Patients and methods: We report on two different cases, a contemporary one and a historical one, highlighting the diversity of clinical presentations and prognoses of these lesions. Furthermore epidemiological aspects, clinical features, and diagnostic and therapeutic work-up in patients with an ectopic meningioma are reviewed. Results: Typically, ectopic meningiomas present as gradually expanding lesions, causing a variety of symptoms by their mass effect. Diagnosis is based on histological characteristics, which are similar to those of intracranial meningiomas. Treatment is primarily surgical. Conclusions: The cases we report are at different ends of the clinical and prognostic spectrum. Therapeutic options for different clinical scenarios are discussed.

Primary intraosseous osteolytic meningioma: a case report and review of the literature

BACKGROUND

Primary intraosseous meningioma is a subset of extradural meningioma that arises in the bone, and only a few cases have been reported to date.

CASE PRESENTATION

An 80-year-old man presented with decreased hearing on the right side accompanied by a disturbance of balance 10 months prior to admission. Magnetic resonance imaging revealed an 8 × 7 cm osteolytic mass in the right posterior fossa related to the petrous bone, with extension to the cervical region. During surgery, the tumor was found to be located extradurally, with no invasion of the dura. The tumor was removed entirely, apart from a small portion around the jugular foramen to avoid lower cranial nerve injury.

CONCLUSION

The final diagnosis was primary intraosseous osteolytic meningioma with atypical pathology. Here, we report a rare case of an osteolytic skull lesion in the skull base not invading the dura and with extensive bone destruction.

A rare case of extracranial meningioma in parapharyngeal space presented as a neck mass

BACKGROUND

Meningiomas are the most common intracranial tumor, but rarely, they can develop extracranially, usually in the neck. There are very few cases of parapharyngeal meningioma reported in literature and little is known about their biological behavior and operative management. We present a patient with a primary parapharyngeal meningioma that presented as an anterior neck mass.

CASE PRESENTATION

The patient is a 55-year-old female who presented with neck mass. A CT scan and MRI revealed a large, well defined, mildly enhancing soft tissue mass located in the right carotid sheath extended from the level of the thyroid gland into the skull base jugular foramen superiorly. Cervical exploration with partial excision of the mass was performed. Histological examination revealed meningiothelial cells with intranuclear inclusions, arranged in a syncytial pattern. Mutiple psamoma bodies these findings are consistent with the diagnosis of meningioma.

CONCLUSION

Extracranial meningiomas are quite rare. The diagnosis of these types of tumors is challenging due to the non specific nature of the symptoms. The anatomic complexity of the region of parapharyngeal space also makes their detection difficult. Imaging modalities can aid in the diagnosis, but pathological examinations are essential in confirming a definite diagnosis.

Calvarial ectopic meningothelial meningioma

BACKGROUND

Meningiomas are the most common benign neoplasm of the brain whereas ectopic presentation, although reported, is rare. Among these ectopic tumors, there are a group of purely intraosseous meningiomas, which usually are diagnosed differentially from common primary osseous tumor such as fibrous dysplasia and osteoid osteoma.

CASE DESCRIPTION

We report a 62-year-old female with a history of headaches and 6 months of progressive right parietal bulging, with no neurological signs. Parietal craniotomy was performed with immediate titanium cranioplasty of the parietal convexity. Histopathology exams revealed an ectopic intradiploic meningioma without invasion of cortical layers, with positive staining for progesterone receptors and epithelial membrane antigen.

CONCLUSIONS

Ectopic intraosseous meningiomas remain a rare neoplasm with only a few cases reported. The main theories to justify the unusual topography appear to be embryological remains of neuroectodermal tissue or cellular dedifferentiation. Surgical treatment seems the best curative option.

Primary Benign Intraosseous Meningioma on (18)F-FDG PET/CT Mimicking Malignancy

We present a case of primary benign intraosseous meningioma in the sphenoid bone mimicking malignancy. A 44-year-old female patient who had a protruding right eye and headache came to our hospital. MRI showed a large, destructive, heterogeneously well-enhancing soft tissue mass in the right sphenoid bone suggesting malignancy. ¹⁸F-FDG PET/CT showed a hypermetabolic mass in the same site with an SUV_max of 9.1 The pathological diagnosis by surgery revealed that this tumor was a WHO grade I transitional meningioma. This case suggests that primary benign intraosseous meningioma may show high ¹⁸F-FDG uptake mimicking a malignancy.

A case of intraosseous microcystic meningioma without a mass lesion

Both intraosseous and microcystic meningiomas are rare tumor types. We report the case of a 66-year-old woman with intraosseous microcystic meningioma without a mass lesion. She presented with a rare intraosseous microcystic meningioma manifesting as pain. Radiological examination revealed an osteolytic lesion in the right parietal bone. Magnetic resonance (MR) images showed iso- to hypointensity on T₁-weighted images and hyperintensity on T₂-weighted images corresponding to the lesion. T₁-weighted MR imaging with gadolinium enhancement better defined the marginal area. The inner table of the skull was disrupted prominently, and both sides of the outer table were eroded. There was fluid leakage during surgery but no obvious tumor mass. Histological examination revealed microcystic meningioma in the inner part of the defective bone. A macroscopic lesion was not found, because most of the tumor comprised microcysts, and their contents leaked out during the surgical procedure. Intraosseous microcystic meningioma may be considered as one of the differential diagnoses when the intraosseous tumor in the skull has fluid leakage and does not have a mass lesion during the surgery.

71-year-old female with right eye proptosis

Meningiomas that arise outside the cranial vault without a dural connection comprise about 1–2% of all meningiomas and are referred to as primary extradural meningiomas (PEMs), intraosseous type 1. When these tumors occur within bone, they may be initially misinterpreted radiologically as a primary bone lesion.We report the case of a 71-year-old woman found to have a right lateral orbital wall mass without dural involvement. Pathology confirmed a PEM and we review the clinical, radiologic, and pathologic features of this case.

Fine-needle aspiration cytology of orbital meningiomas

Meningiomas are benign tumors derived from arachnoid cells. Most commonly they arise within the cranial cavity, but they may arise extracranially in various anatomic sites. We present four cases of orbital meningiomas diagnosed on fine-needle aspiration cytology (FNAC) and confirmed on histopathology. All the cases are presented with orbital mass. FNAC smears showed classical whorling and syncytial pattern of cells, with round to oval nucleus, inconspicuous nucleoli and one each case showed intranuclear inclusion and psammoma bodies. FNAC diagnosis of such lesions is difficult, because cytological features may mimic other soft tissue lesions located in orbital region. Awareness of this entity and its cytological appearance is important to allow correct diagnosis.

Primary intraosseous meningioma

✓Primary intraosseous meningiomas are a subtype of primary extradural meningiomas and constitute fewer than 2% of meningiomas overall, but they represent approximately two thirds of all extradural meningiomas. These types of meningiomas originate within the bones of the skull and thus can have a clinical presentation and radiographic differential diagnosis that is different from those for intradural meningiomas.

Primary intraosseous meningiomas are classified based on their location and histopathological characteristics. Treatment primarily involves resection with wide margins if possible. Very little literature exists regarding the use of adjuvant therapies such as radiation and chemotherapy for these tumors. In fact, the literature regarding primary intra-osseous meningiomas consists mostly of clinical case reports and case series. This literature is reviewed and summarized in this article.

Meningioma of the mandible: imaging with CT

We present the first description of CT of a meningioma of the mandible in the literature. Extracranial meningiomas are exceedingly rare. There have been 3 cases of meningioma of the mandible described in the literature, but none characterized with cross-sectional imaging. We describe the clinical and CT features used to establish the diagnosis as well as how to differentiate this lesion from other pathology of the mandible.

Dural involvement in primary extradural meningiomas of the cranial vault

Object

The authors retrospectively analyzed a consecutive series of patients with cranial vault primary extradural meningioma (PEM), with particular regard to the tumor’s dural involvement. The pertinent literature was reviewed.

Methods

Clinical data were retrospectively obtained in a consecutive series of 16 patients treated for a PEM at two institutions between 1992 and 2004. The authors created a classification system based on dural involvement of the tumors.

Nine women and six men (mean age 55 years) presented with a painless, slowly progressive swelling. Preoperative magnetic resonance (MR) imaging revealed dural enhancement at the site of tumor in 11 patients. On surgical inspection, the tumor infiltrated the dura in all but three patients. Histological examination of tissue samples demonstrated tumor infiltration of the dura in all 14 patients in whom the dura had been resected. Three recurrent tumors were observed on follow-up examination during a mean period of 5.8 years (range 1.5–13 years) and required extirpation. In addition to one patient in whom there was histological evidence of malignancy, the other two cases involved two patients in whom no apparent dural involvement was observed during the first surgery. In a review of the literature, the authors found that histological examination showed dural involvement in 22%; the dura was not histologically evaluated in the remaining patients (78%). Postoperative follow-up data exceeding 2 years were only provided in two of the reported cases.

Conclusions

Tumor infiltration of the dura should be assumed in PEMs of the cranial vault, and resection of the dura at the site of craniotomy is recommended to prevent tumor recurrence.

Méningiome intra-osseux de la voûte du crâne : confrontation anatomo-radiologique

Intraosseous meningiomas are rare ectopic meningiomas. The authors report the case of a hyperostotic intraosseous meningioma of the parietal bone without dural extension. The preoperative imaging findings, as well as imaging features of the surgical specimen and pathologic findings are discussed.

Psammomatous extra-calvarial meningioma of the neck

A case of Primary extraraniul meningioma of the parapharyngcal space arising simulitueouly as two distinct tumour masses from two sepurae cranial nerves is reported. The paucity of reported eases is the evidence for its rarily.

Intraosseous meningioma of the posterior fossa--Case report

A 62-year-old male presented with a rare intraosseous meningioma with intradural extension manifesting as frequent vomiting and floating sensation that had persisted for 3 months. Neuroimaging detected a mass lesion that was mainly located extradurally in the right posterior fossa with a daughter lesion inside the dura. He underwent surgical excision of the mass lesion. Craniectomy exposed the main lesion of the tumor just beneath the thinned outer table of the skull, and in the extradural space, with the daughter lesion penetrating the dura. Both portions of the tumor were resected. There was no attachment to the adjacent dura mater. Histological examination showed meningotheliomatous meningioma containing scattered bony tissue. This intraosseous meningioma probably originated from the occipital bone with a small intradural extension caused by mechanical compression.

Primary extradural meningiomas: a report on nine cases and review of the literature from the era of computerized tomography scanning

OBJECT

Primary meningiomas arising outside the intracranial compartment (primary extradural meningiomas [PEMs]) are rare tumors. To develop a better understanding of these tumors and to establish a comprehensive classification scheme for them, the authors analyzed a series of patients treated at the M. D. Anderson Cancer Center (MDACC) and reviewed all cases reported in the English-language literature since the inception of the use of computerized tomography (CT) scanning.

METHODS

Clinical records, results of radiographic studies, and histological slides were reviewed for all cases of PEM at MDACC. Demographic features, symptoms, tumor location, histological grade, and patient outcome were assessed in all cases. A comprehensive literature search identified 168 PEMs in 142 patients reported during the CT era. These reports were also analyzed for common features. Tumors for both data sets were classified as purely extracalvarial (Type I), purely calvarial (Type II), and calvarial with extracalvarial extension (Type III). Type II and Type III tumors were further categorized as convexity (C) or skull base (B) lesions. The incidence of PEMs at MDACC was 1.6%, which was consistent with the rate reported in the literature. In both data sets, the male/female ratio was nearly 1:1. The most common presenting symptom was a gradually expanding mass. The age of patients at diagnosis of PEM was bimodal, peaking during the second decade and during the fifth to seventh decades. In all MDACC cases and in 90% of those reported in the literature the PEMs were located in the head and neck. The majority of tumors originated in the skull (70%). In the MDACC series and in the literature review, the majority (67% and 89%, respectively) of tumors were histologically benign. Although fewer PEMs were malignant or atypical (33% at MDACC and 11% in the literature), their incidence was higher than that observed for primary intracranial meningiomas. Distant metastasis was not a common feature reported for patients with PEMs (6% in the literature). Outcome data were available in 96 of the cases culled from the CT-era literature. The combination of the MDACC data and the data obtained from the literature demonstrated that patients with benign Type IIB or Type IIIB lesions were more likely to experience recurrence than patients with benign Type IIC or Type IIIC tumors (26% compared with 0%, p < 0.05). The more aggressive atypical and malignant tumors were associated with a statistically significant higher death rate (29%) relative to benign tumors (4.8% death rate, p < 0.004).

CONCLUSIONS

Defining a tumor as a PEM is dependent on the tumor's relation to the dura mater and the extent and direction of its growth. Classification of PEMs as calvarial or extracalvarial and as convexity or skull base lesions correlates well with clinical outcome.

Diffuse calvarial meningioma. Case report and review of the literature

An extremely unusual calvarial meningioma in a 77-year-old woman is reported. The meningioma spread widely and symmetrically within the calvaria and grew extracranially within the scalp as well as intracranially. Reactive dural hyperplasia induced narrowing of the intracranial space and occlusion of the superior sagittal sinus, resulting in intracranial hypertension. After external decompression, the patient's symptoms markedly resolved. The authors review the literature on calvarial meningioma, discuss its pathogenesis, and propose mechanisms responsible for the patient's intracranial hypertension.

Ectopic dural osteolytic meningiomas

Intracranial meningiomas usually originate from the arachnoidal cells of the internal dural layer: meningiomas that originate from different sites are ectopic. The authors describe the case of a small meningioma adhering to the external dural layer without involvement of the internal layer, accompanied by osteolysis of the internal surface of the skull. A review of the literature on cranial ectopic meningiomas yielded only four cases described as originating from the external dural layer. Osteolysis of the skull was always present and was not found to have prognostic significance. The authors suggest that these four primary ectopic meningiomas originating from the external dural layer should be differentiated from intraosseous meningiomas of the skull.

Primary intraosseous meningioma. Case report

Primary intraosseous meningioma of the skull is an uncommon lesion often confused preoperatively with a primary bone tumor of the skull. The case of an intraosseous meningioma without dural connection or association with a cranial suture is reported that was radiographically diagnosed as Paget's disease and initially treated conservatively. Persistent headache prompted a biopsy, yielding a benign, heavily ossified, and psammomatous meningioma. The lesion was treated with wide surgical excision and acrylic cranioplasty. Subsequent review of the literature has revealed 35 additional cases of purely intraosseous meningioma. An analysis of these 36 cases demonstrates a mean patient age at diagnosis of 45 years and a 2:1 female preponderance, with the majority of lesions associated with cranial sutures. Sixty-four percent of the lesions were hyperostotic on plain skull x-ray films; the rest were osteolytic or a mixture of both. There was no relationship to prior trauma. The treatment of choice is wide surgical resection followed by cranial reconstruction.

Association of primary intraspinal meningiomas and subcutaneous meningioma of the cervical region: case report and review of literature

A report is made of a unique combination of occurrences of primary intraspinal epidural and subdural meningiomas and primary subcutaneous meningioma in the cervical region of a 15-year-old boy. The subcutaneous meningioma was detected at birth. Review of 92 recorded cases of primary dermal meningiomas revealed that they tended to occur in young patients, with an average age of 34 years for both sexes. The female-to-male ratio was 4:5. Most cutaneous meningiomas occurred in the head and neck, and the scalp was the most common site.

Extracranial meningioma of the oral cavity

A case of a maxillary tumour resembling an extracranial meningioma is reported. So far as can be ascertained no other instance of this same tumour has been recorded occurring in the oral cavity.

Meningioma: a case of transcranial recurrence managed by base-of-skull technique and a review of the tumor

Meningiomas are the most common benign intracranial neoplasms, and although the otolaryngologist rarely sees these lesions, he or she may encounter them in surgery of the skull base. Surgical removal is the primary treatment modality for these meningiomas. To avoid recurrent disease, the best initial therapy is the most extensive procedure that can reasonably be effected. Chemotherapy and irradiation therapy have, at best, only limited roles in treatment.

Pathology consultation. Extracranial meningiomas

Extracranial meningiomas are most often due to extension from an intracranial primary and less so from meningocytic cells found with arachnoid clusters or modified mesenchymal cells. The most common presentation of all forms is cutaneous, either primary or secondary. Orbital, paranasal, temporal bone and oral presentations follow in that order.

Meningiomas invading the temporal bone with extension to the neck

Meningiomas are the second largest group of brain tumors after gliomas. They account for 13 to 18 per cent of all primary intracranial neoplasms. The majority occur in the cerebral chamber; only 8 to 9 per cent are located in the cerebellar chamber. Meningiomas are hamartomatous, not truly neoplastic tumors, which arise from dural fibroblasts and particularly from arachnoid cells that tend to cluster around the tips of the arachnoid villi. Their preferential sites correspond closely with the locations where arachnoid villi are most frequently encountered, namely, along the major venous sinuses and their contributory veins, at the foramina of exit of the cranial nerves, and where arachnoid cell clusters are found within the trunk or the perineural sheaths of cranial nerves within or adjacent to the basal foramina. Of all intracranial meningiomas, 20 per cent eventually develop an extracranial extension. These extracranial extensions project, in order of decreasing frequency, to 1) the orbit, 2) the external table of the calvaria, 3) the nasal cavity and paranasal sinuses, and 4) the parapharyngeal (cervical) space. Once a meningioma has gained access to the temporal bone, its tendency to extend beyond the confinements of the skull increases to 43 per cent. The most frequent pathway is through the jugular and lacerate foramina into the parapharyngeal space, where it may manifest as a nasopharyngeal, oropharyngeal, retromaxillary, retromandibular, or cervical neck mass. A meningioma in the parapharyngeal area can represent 1) an extracranial extension of a primary intracranial tumor, 2) a neoplasm arising in the jugular foramen, 3) a neoplasm originating from an arachnoid cell cluster within the trunk of a cranial nerve or its perineural sheaths within or near a neural foramen, or 4) a metastasis to a cervical lymph node from a primary intracranial meningioma. Meningiomas extending to the neck are unique because of their tendency toward extracranial expansion, higher incidence of local recurrence, multicentric growth, and frequent combination with other neoplasms of the central nervous system. They are frequently an expression of the central form of neurofibromatosis (von Recklinghausen's disease).

Extracranial meningioma

A patient is presented with findings of separate intracranial and extracranial meningiomas, each of a different histologic type. A calcified fibrous meningioma, with secondary psammomatous features, presented as a left neck mass associated with hoarseness, dysphagia, a unilateral facial weakness and hearing loss. A noncalcified asymptomatic intracranial syncytial meningioma was discovered in the left frontal lobe after computerized tomographic and angiographic study of the cranial contents. The origin of the extracranial meningioma producing multiple unilateralcranial nerve disturbances and serous otitis media is discussed. The noncontiguous tumors in this patients are felt to have separate origins, with the extracranial lesion most likely arising in the temporal bone.

Intra and extracranial meningiomas involving the temporal bone

Meningiomas involving the temporal bone are very rare. Until 1964, only 39 cases had been reported in the world literature. Most series reported are very small and a physician is unable, based on his own experience, to acquire a sufficient knowledge about this entity and may raise serious doubts regarding the diagnosis and management of these tumors. In the past nine years the author has encountered five cases of meningiomas involving the temporal bone. This became a stimulus for a thorough research of the world literature of meningiomas in general, with emphasis on temporal bone involvement. Nine more cases were collected from cooperative physicians with whom the author has been associated. These 14 cases are the clinical material analysed in this study. This thesis is divided into three sections: 1. Exhaustive review of the world literature on meningiomas with emphasis on involvement of the temporal bone. 2. A detailed presentation and discussion of the clinical material stressing the importance of the newer diagnostic methods available and the most modern microsurgical techniques used in otological and neurological surgery procedures, applied to the treatment of those lesions. A light microscopic histopathological study of all cases reported is presented. Electronmicroscopy demonstrates the true intracellular nature of an atypical, recurrent meningioma occurring in a child. 3. A critical evaluation of the cases presented and the value of the diagnostic and therapeutic methods applied in this series of patients are here analysed. Conclusions are then drawn based on the experience and knowledge accumulated in this study. The histopathological diagnosis of meningiomas sometimes is difficult. Probably those tumors involve the temporal bone more commonly than has been reported in the literature. Some of these lesions probably are being misdiagnosed as chemodectomas or other neoplasias. Computerized axial tomography, particularly applied to the diagnosis of brain lesions, is the major break-through of recent modern medicine. A noninvasive technique, when used with contrast enhancement, offers great diagnostic possibilities. Early diagnosis of meningiomas and their complete surgical excision are the key factors necessary for a successful result with a good prognosis and a low recurrence rate. Although these tumors are classically considered radioresistant, radiotherapy may play a role in the treatment of incompletely excised lesions or in patients of a poor surgical risk. Further experiences and time will probably lead to more definite conclusions regarding the role of radiation therapy or the combined surgical and postoperative radiation treatment. Of all brain tumors, meningiomas offer the best prognosis.