Ependymoma and intraparenchymal calcifying pseudoneoplasm of the neural axis: incidental collision or unique reactive phenomenon?

Spinal calcifying pseudoneoplasm of the neuraxis (CAPNON) associated with facet joint pathologies: CAPNON diagnostic and pathogenic insights

Calcifying pseudoneoplasm of the neuraxis (CAPNON) is a rare tumor-like fibro-osseous lesion that can develop anywhere in the neuraxis. Approximately a half of reported CAPNONs developed in the spinal region, mostly close to the facet joint (FJ). The diagnosis of spinal CAPNONs is challenging given the existence of mimics and associated pathologies including calcific degeneration of the FJ ligaments (DFJL) and synovial cysts (SCs). The pathogenesis of CAPNON remains elusive, although there have been a few hypotheses including degenerative, reactive, proliferative and immune-mediated processes. Our present study examined clinical, radiological and pathological features of 12 spinal CAPNONs in comparison to 9 DFJL foci, and diagnostic and pathogenic relationship between CAPNONs and FJ pathologies. On imaging, CAPNONs were all tumor-like and typically bigger than DFJL foci. All CAPNONs showed pathologically diagnostic features including characteristic cores, consistently identifiable core-surrounding/peripheral palisading of macrophages and other cells including multinucleated giant cells, variable infiltration of CD8+ T-cells, and multifocal immunopositivity of neurofilament light chain (NF-L). These features were absent or limited in the DFJL foci with statistically significant differences from CAPNONs, except calcifications. Spinal CAPNONs co-existed with DFJL foci in all cases; some had transitional foci with overlapping focal CAPNON and DFJL-like features. These findings, along with our previously reported relationship between CAPNONs and SCs, suggest that spinal CAPNONs may occur in association with or in transition from calcifying/calcified degenerative lesions of FJ ligaments and/or SCs when a reactive proliferative process is complemented by other pathogenic changes such as immune-mediated pathology and NF-L deposition/expression.

Calcified Pilocytic Astrocytomas and Calcifying Pseudoneoplasms of the Neuraxis: A Diagnostic Challenge

Pilocytic astrocytoma (PA), recognized as the most prevalent central nervous system (CNS) tumor, has long been associated with calcifications, a characteristic often attributed to benign or indolent growth patterns. In this study, we explored the calcified attributes in these tumors that beckon a deeper understanding. This is a retrospective study, on a set of seven cases, with a histopathological diagnosis of pilocytic astrocytoma with calcifications and psammoma bodies (PB). Despite an encouraging overall survival outcome, the recurrence in four cases cast some doubt on the conventional classification. The histological study of these cases revealed a spectrum of calcifications, varying in size and morphology, all of which exhibited positive reactivity to glial fibrillary acidic protein (GFAP), osteoconduction, and osteopontin. Notably, the immunohistochemistry showed hyaline bodies displaying an atypical immune profile, strikingly negative for vimentin and GFAP, and a robust positivity for epidermal growth factor receptors (EGFR), tumor necrosis factor-alpha (TNF-α), and interleukin 1 beta (IL-1β). These results stimulated speculation that the identity of these calcified tumors may have extended and potentially embraced the realm of calcifying pseudoneoplasms of the neuraxis (CAPNON), underscored by intense pilot gliosis. This study transcends mere anatomical exploration; it delves into the intricacies of calcified tumors, casting a spotlight on the dynamic interplay between PA and CAPNON. As we traverse the frontiers of neuro-oncology, these findings pave the way for innovative avenues in the diagnostics and therapeutics of these tumors.

Calcifying Pseudoneoplasm of the Neuraxis: An Institutional Series of Ten Cases and Review of the Literature to Date

BACKGROUND

Calcified pseudoneoplasms of the neuraxis (CAPNONs) are rare, fibro-osseous lesions with an unknown cause that may present anywhere along the neuroaxis. Little is known about how intracranial CAPNONs present and about patients' long-term outcomes.

METHODS

A retrospective institutional review of intracranial pathology-confirmed CAPNONs was performed. Presenting clinical features, management, and clinical outcomes are highlighted. A literature review of intracranial CAPNON lesions was also performed to build on our series.

RESULTS

Ten patients were identified who met the inclusion criteria. Most patients presented with headaches (n = 6; 60%), seizures (n = 5; 50.0%), and neck and facial pain (n = 3; 30.0%). Most lesions were supratentorial (n = 7; 70.0%), with 3 infratentorial origins. Surgical resection was the most common initial management undertaken (n = 7; 70.0%). No new permanent postoperative neurologic deficits were identified. The median clinical and/or radiographic follow-up for all patients was 6.8 years (range, 0.7-23.3 years), with no recurrence of disease for 5 patients who underwent gross total resection. Four of 5 patients with residual or nonresectable lesions showed no interval growth on radiographic follow-up; 1 patient showed progression and worsening of presenting symptoms 2 months after resection. Resection substantially improved seizures and headaches in patients presenting with these symptoms (80% and 83.3%, respectively).

CONCLUSIONS

Intracranial CAPNONs may present with a wide variety of symptoms characteristic of the site of origin. The outcomes of these symptoms regarding survival and disease control are generally favorable, although resection does not always yield complete resolution of presenting deficits in certain patients, particularly those presenting with headaches or neck/facial pain.

Posterior Fossa Calcifying Pseudoneoplasm of the Neuraxis (CAPNON): Presentation of Three Surgical Cases

BACKGROUND

Calcifying pseudoneoplasm of the neuraxis (CAPNON) is an extremely rare entity with fewer than 150 cases reported in the literature and mostly with a supratentorial or spinal location. Posterior fossa CAPNON has been reported scarcely, and association with perilesional edema is a topic not yet approached which might play a significant role in treatment decision and clinical progression. Our objective is to report, to our knowledge, the first series of 3 posterior fossa CAPNON surgically treated in a single institution and assess features that help provide a systematic approach to diagnosis and timely treatment.

METHODS

This was a monocentric, retrospective study of surgical patients diagnosed with a posterior fossa CAPNON in the last 5 years. A thorough bibliographic research was conducted.

RESULTS

Three patients were included. Locations involved IV ventricle, right cerebellopontine angle with extension to foramen magnum, and cerebellar vermis. Two of them presented with symptoms linked to acute hydrocephalus, and the other one presented with progressive cranial nerve palsy and brainstem compression signs. The 3 of them showed radiological signs of perilesional edema on their preoperative magnetic resonance imaging. Gross total resection was accomplished in one case, with near and subtotal resections in the others. There were no complications. The outcome was favorable in all cases.

CONCLUSIONS

It is essential to contemplate this infrequent diagnosis in cases of calcified lesions involving the posterior fossa. When symptoms manifest, surgery should be considered. Perilesional edema could be associated with symptomatic progression and hence a sign suggesting the need for surgical treatment.

Calcifying Pseudoneoplasm of the Neuraxis in the Posterior Fossa: A Case Report and Literature Review

Calcifying pseudoneoplasm of the neuraxis are rare fibro-osseous lesions that can occur throughout the central nervous system. This paper reports one case of this lesion within the posterior fossa and contains a literature review of all cases documented within the posterior fossa to date. A 53-year-old female patient with a history of epiphora, facial irritation, and headaches was found to have a mass centered in the posterior fossa. The patient underwent surgical resection for removal of the mass. Upon review by pathology, the final diagnosis was consistent with calcifying pseudoneoplasm of the neuraxis.

Calcifying pseudoneoplasm of neuroaxis (CAPNON): a comprehensive immunohistochemical and morphological characterization of five cases

Calcifying pseudoneoplasm of neuroaxis (CAPNON) is a rare lesion of the central nervous system with uncertain histogenesis. We further explored phenotypic spectrum of the entity with respect to possible histogenesis. We collected 5 cases of CAPNONs, performed a detailed morphological assessment, and performed an extensive immunohistochemical analysis (EMA, progesterone receptors, MUC4, SSTR2A, cytokeratin AE1/3, cytokeratin 18, GFAP, neurofilaments, desmin, nestin, synaptophysin, S100 protein, SOX10, CD56, Podoplanin, SATB2, ERG, CD45, and CD163) to elucidate the histogenesis. Furthermore, we performed NGS analysis of one case. The clinical course was benign in all cases. All lesions showed extensively calcified matrix in multilobular arrangement, with a palisade of osteoblast-like cells. Characteristic fibrohyaline matrix was notable in 4/5 cases, while one case was myxoid with rod-like calcifications. Metaplastic lamellar bone was present in 4/5 cases and psammoma bodies were present in 2/5 cases. In 4/5 cases, areas of entrapped glial tissue were present. Expression of EMA was focally present in 3/5 cases, SSTR2A and nestin in 2/5 cases, and progesterone receptor in 2/5 cases in rare cells. We did not observe concomitant expression of EMA, SSTR2A, and progesterone receptor in the same cellular subsets. In one case, NGS showed multiple chromosomal alterations and missense mutation in PIK3CA, attributable to the admixed meningothelial population compatible with meningioma. In another case, biphasic proliferation with myoepithelial phenotype was present. The lesions showed no lineage-specific immunoprofile. Additional pathology was identified in two cases, furthermore suggestive of a possible reactive origin of the lesion.

Calcified Pseudoneoplasm of the Neuraxis

Calcified pseudoneoplasms of the neuraxis are extremely rare non-neoplastic lesions that can exist anywhere in the CNS. Although benign, the lesions can cause substantial neurologic symptoms, typically related to mass effect on adjacent structures. Calcified pseudoneoplasms of the neuraxis can also mimic other entities such as calcified oligodendrogliomas and meningiomas. Nevertheless, the lesions can usually be strongly suggested at the time of imaging due to a number of fairly unique imaging characteristics. Here, the clinical presentation of a patient with a posterior fossa calcified pseudoneoplasm of the neuraxis is described, along with its imaging and pathologic features.

Calcifying Pseudoneoplasm of the Neuraxis: From Pathogenesis to Diagnostic and Therapeutic Considerations

Calcifying pseudoneoplasm of the neuraxis (CAPNON) is a rare tumefactive lesion that can develop anywhere within the neuraxis. The incidence is likely underreported, given its nonspecific imaging features and because CAPNON has often been overwhelmed by the presence of comorbid disease. CAPNON is typically diagnosed by the histopathological examination findings. However, the histopathological diagnosis is often challenging owing to the existence of similar calcifying pathological entities. Although the pathogenesis of CAPNON has remained elusive, emerging evidence supports a reactive proliferative and immune-mediated process involving the aggregation of neurofilament light chain protein and the infiltration of immune cells. The management of CAPNON is largely dependent on the symptoms, which are mainly related to the location and associated mass effects. Maximal surgical resection will result in excellent patient outcomes with rare recurrence, especially in patients presenting with epilepsy. The discovery of neurofilament light chain protein within CAPNON suggests that neurofilament might be implicated in the pathogenesis of CAPNON, serve as an immunohistochemical marker to improve the diagnostic accuracy of CAPNON, and hold therapeutic potential for the treatment of CAPNON.

Calcifying Pseudoneoplasm of the Neuraxis Involving the Posterior Skull Base: A Case Report and Literature Review

Calcifying pseudoneoplasm of the neuraxis is an uncommon, nonneoplastic fibro-osseous lesion of the central nervous system. At the time of this report, at least 150 cases have been reported in the literature. Because of the rarity of this lesion, it is often diagnostically challenging for radiologists and pathologists alike. In this article, we present a case of a 44-year-old woman with a 5.8-cm intracranial/skull base calcifying pseudoneoplasm of the neuraxis that was concerning for osteosarcoma on initial frozen section. Permanent sections revealed bone and fibrous stroma, calcifications, and nests of histiocytes with granuloma formation. Scattered, focally dense inflammatory foci and spindled cells outlining abundant large nodules of chondromyxoid matrix were also present. In this case report, we also reviewed recent literature for clinical presentations, radiologic findings, and histologic differential diagnoses. Familiarity with this lesion is important to avoid misdiagnosis leading to unnecessary and potentially harmful treatment.

Collision Lesions of Calcifying Pseudoneoplasm of the Neuraxis and Rheumatoid Nodules: A Case Report With New Pathogenic Insights

Calcifying pseudoneoplasm of the neuraxis (CAPNON) is a rare tumor-like lesion with unclear pathogenesis. Collision lesions of CAPNONs with neoplasms are occasionally reported. In this article, we report the first case of collision lesions between CAPNON and rheumatoid nodules (RNs) in a patient with systemic lupus erythematosus. The patient was a 51-year-old female who presented with lower back pain and subsequently a lower back mass over 2 years. Spinal magnetic resonance imaging demonstrated a heterogeneous, partially calcified mass centered in the L3-4 paravertebral regions. A biopsy of the mass was diagnostic of CAPNON. As the mass grew over the following 5 months, it was resected en bloc. Its pathological examination revealed collision lesions of RNs at different histopathological stages and CAPNON lesions, and transitional lesions exhibiting combined RN and CAPNON features, with immune cell infiltrates. Our findings provide new evidence for an immune-mediated reactive process and insights into the pathogenies of CAPNON.

New insights into calcifying pseudoneoplasm of the neuraxis (CAPNON): a 20-year radiological-pathological study of 37 cases

AIMS

Calcifying pseudoneoplasm of the neuraxis (CAPNON) is a rare entity that can occur anywhere within the central nervous system. Histologically, CAPNON has been characterised as a benign, calcified, fibro-osseous lesion with a characteristic chondromyxoid fibrillary matrix with dense calcification and varying degrees of spindle, epithelioid, fibrous, meningothelial and giant cells. The underlying aetiology of CAPNON is controversial and incompletely understood. The aim of this study was to perform a comprehensive radiological and histological review to further characterise this entity.

METHODS AND RESULTS

In this article, we review our institutional 20-year experience including 37 cases of CAPNON with detailed pathological analysis, evaluation of concurrent lesions, correlation with radiological imaging, and critical review of the literature. The classic histological finding of chondromyxoid matrix was present in one-third of cases. Underlying or dual pathologies were frequent, and included diverse underlying conditions. Radiologically, dense calcification and dural attachment were the most common features. Enhancement was often low, but was more prominent in the setting of inflammatory changes, aggressive growth, and dual pathology.

CONCLUSION

Our results suggest that CAPNON represents a spectrum of reactive processes that can arise in association with diverse underlying pathologies, including inflammatory, degenerative, vascular and neoplastic lesions.

Calcifying pseudoneoplasm of the neuroaxis presenting with refractory seizures: Case report and literature review

Calcifying pseudoneoplasms of the neuraxis (CAPNON) are rare benign lesions that can arise anywhere within the central nervous system. The etiology of these lesions remains unknown and diagnosis is made on pathohistological analysis. We present the case of a 35-year-old male patient with a history of epilepsy since childhood who was evaluated for refractory seizures. MRI revealed a small lesion in the left-posterior temporal lobe suspected to be a cavernoma. A gross total resection of the lesion was achieved via a left temporal craniotomy and pathological analysis revealed CAPNON. At 6 months follow-up, the patient remained neurologically intact and his seizures had ceased.

Incidental multifocal calcifying pseudoneoplasm of the neuraxis: case report and literature review

Calcifying pseudoneoplasm of the neuraxis (CAPNON) is thought to be a rare tumefactive lesion with unknown pathogenesis. Its prevalence is questionable with few previously reported cases of incidental CAPNON, and likely underdiagnosis. We report a unique case of incidental multifocal CAPNON. A 64-year-old female was admitted with loss of consciousness due to a ruptured right middle cerebral artery aneurysm with subarachnoid and intraventricular hemorrhage. She has a craniotomy and clipping. At time of operation, numerous small dural-based nodules were found, and one was excised for biopsy and was diagnosed as CAPNON. Retrospective review of her CT images identified nodules that were all ipsilateral to the ruptured aneurysm. A literature review revealed that incidental and/or multifocal CAPNONs are rare but likely underreported. Our case suggests a reactive process in the pathogenesis of CAPNON.

Sudden Death Due to Calcifying Pseudoneoplasm of the Neuraxis: A Case Report and a Review of Sudden Death Due to Undiagnosed Central Nervous System Mass Lesions

We present a case of a 22-year-old man who died unexpectedly after a seizure due to a previously undiagnosed calcifying pseudoneoplasm of the neuraxis (CAPNON). Calcifying pseudoneoplasm of the neuraxis is a rare entity, and this is, to our knowledge, the first described case of sudden death due to CAPNON. Sudden death due to undiagnosed central nervous system mass lesions is rare, and most cases are attributable to hemorrhage, hydrocephalus, or increased intracranial pressure due to mass effect. Seizure is a rare cause of sudden death due to central nervous system mass lesions. This case highlights that mass lesions may cause sudden death due to seizure, even without other pathologic evidence of a cause of death, such as hemorrhage or edema. Furthermore, benign, reactive, and low-grade mass lesions may cause sudden death due to seizure. Seizure should remain in the autopsy differential as a cause of death, even where there is no pathologically evident mechanism by which a mass lesion caused death.

Surgically treated intracranial supratentorial calcifying pseudoneoplasms of the neuraxis (CAPNON) with drug-resistant left temporal lobe epilepsy: A case report and review of the literature

Calcifying pseudoneoplasms of the neuraxis (CAPNON) are rare pathological lesions that can present anywhere in the central nervous system. Symptoms vary depending on the location, though they often include seizures, especially in intracranial and supratentorial lesions. A case of intracranial supratentorial CAPNON presenting with drug-resistant left temporal lobe epilepsy is reported. The patient had a history of drug-resistant focal seizures for over 36 years. The lesion was located in the left mesial temporal lobe, but hippocampal sclerosis and hippocampal invasion were not apparent. The lesion was removed without hippocampectomy, and the patient has been seizure-free for one year.

Multiple Calcifying Pseudoneoplasms of the Neuraxis

Calcifying pseudoneoplasms of the neuraxis (CAPNONs) are extremely rare tumors that are frequently misdiagnosed and overlooked by clinicians. To date, only 40 intracranial lesions have been reported, and in all instances, they were found as a solitary calcified mass. To our knowledge, the current case report is the first to illustrate the development of multiple intraaxial CAPNONs and shed more light on the origin of these lesions.

We discuss the case of a 67-year-old woman who presented with a six-year history of recurrent seizures. Magnetic resonance imaging revealed two similar heterogeneous intracranial masses in the ventral midbrain and left frontal white matter with indications of more aggressive behavior in the supratentorial tumor. The lesion was resected, and histopathological analysis showed tissue containing nodules of chondromyxoid material with a coarsely fibrillar matrix and focal alveolar pattern. Palisading cells were noted around the edges as well as dystrophic calcifications and osseous metaplasia, consistent with CAPNON. Interestingly, the patient had a previous history of multiple brain abscesses and a mycotic aneurysm. At her four-month follow-up visit, the patient remained seizure-free and there were no indications of residual tumor or recurrence.

In contrast to previous reports, intracranial CAPNONs may manifest as multiple lesions and clinicians should include these tumors in the differential diagnosis of intra-axial calcified masses. The previous history of brain abscesses raises the suspicion of an abnormal proliferative process following an insult to the brain tissue as the underlying origin of these lesions.

Radiologic and Histopathologic Features of Calcifying Pseudoneoplasm of the Neural Axis

Aim

To describe the radiologic and corresponding histopathologic features of calcifying pseudoneoplasms of the neural axis.

Methods

Two cases of calcifying pseudoneoplasm of the neural axis were retrospectively reviewed. The first case was documented in a 64-year-old woman, who presented with lower back pain with radiation to her left leg. The second case was documented in a 70-year-old man, who presented with headaches. Medical records, radiologic and histologic findings, and related literature were reviewed.

Results

In the first case, imaging of the lumbar spine revealed a 3.8 × 2.2-cm calcified lesion at the level of vertebrae L5 and S1. A subsequent excision exposed an extradural lesion at L5. Histopathologic examination showed amorphous and granular calcifying material with occasional fibrohistiocytic and giant cell reaction, consistent with calcifying pseudoneoplasm of the neural axis. In the second case, imaging of the head revealed a 2.4 × 2.6-cm well-circumscribed, lobulated, calcified lesion within the basal frontal lobe. Subsequent resection exposed an intradural mass with a nodular arrangement of amorphous and granular calcifying material associated with fibrohistiocytic and giant cell reaction. Both patients had a favorable postoperative course and failed to show any clinical or radiologic sign of recurrence.

Conclusion

Calcifying pseudoneoplasm of the neural axis is an uncommon condition with an excellent prognosis but is often misdiagnosed due to its nonspecific clinical presentation and varied findings on radiology.

Occipital calcified pseudoneoplasms of the neuraxis (CAPNON): understanding a rare pathology

Calcifying pseudoneoplasms of the neuraxis (CAPNON) are rare and typically benign lesions that can occur anywhere within the central nervous system. Aetiology of this lesion is unclear and surgical removal is usually curative. We present a 24-year-old male patient with a history of occipital migraines who was admitted after sudden onset seizure and loss of vision. CT and MRI demonstrated a small calcifying lesion in the right temporo-occipital lobe. The patient underwent gross total resection of the tumour mass and pathological analysis revealed a CAPNON. The preoperative diagnosis of CAPNON remains difficult due to unspecific radiological findings, yet a clear understanding of characteristic pathological findings and prognosis of CAPNON remains paramount.

Supratentorial calcified pseudotumour: experience of a single institution and review of the literature

BACKGROUND

Calcified pseudotumours (CPTs) are rarely found in the central nervous system (CNS). Information on supratentorial CPT is limited. We add our experience treating three supratentorial CPTs. Clinical presentation, pathological findings and clinical course are discussed, and a literature review is provided.

METHOD

Between September 2011 and December 2012, three patients (age range 33-60 years) were diagnosed with symptomatic supratentorial CPTs, for which they underwent resection. Their clinical, radiological, and surgical data were retrospectively retrieved from their medical records and reported.

RESULTS

Symptoms at presentation included headache (n = 1), blurred vision (n = 1), and cognitive decline (n = 1). One tumour was in the left frontal lobe very close to the convexity surface, and the other two were in the midline adjacent to the corpus callosum. Radiological features included a calcified mass on computerised tomography (n = 3), a hypointense (n = 2) or hyperintense (n = 1) signal on T2 and a rim of enhancement with some non-homogenous lesional enhancement on T1-gadolinium (Gd) sequences on magnetic resonance imaging (n = 2). Two patients underwent gross total resection and had an uneventful postoperative course. The third underwent partial removal due to the tumour's adherence to adjacent vascular structures and suffered postoperative complications. On pathology, all lesions had low cellularity fibrovascular tissue mixed with lobules of a haematoxylinophilic, chondromyxoid-like matrix surrounded at its periphery by a variable layer of palisading spindle, epithelioid or multinucleated giant cells. All three CPTs had focal inflammatory infiltrates and variable degrees of metaplastic calcification and ossification.

CONCLUSIONS

Surgical removal is recommended for benign intracranial CPTs that are symptomatic, are associated with brain oedema, or show tumour growth. Stable and asymptomatic CPTs can be followed.

Posterior fossa calcifying pseudoneoplasm of the central nervous system

Calcifying pseudoneoplasms of the neuraxis are rare, poorly understood masses that may arise throughout the CNS. Although these lesions are generally considered benign and noninfiltrative, reports exist that document growth of these masses on serial plain radiographs. The authors report a case of a posterior fossa calcifying pseudoneoplasm of the neuraxis demonstrating interval development of peritumoral edema on serial MRI. Their findings suggest that these lesions may sometimes behave in a more aggressive manner than commonly thought.

Calcifying pseudoneoplasms of the skull base presenting with cranial neuropathies: case report and literature review

Objectives We report our institutional experience with calcifying pseudoneoplasms of the skull base that presented with cranial neuropathies. These lesions are also known as fibro-osseous lesions, cerebral calculi, or brain stones.

Results One patient presented with facial numbness and retro-orbital pain secondary to compression of the maxillary branch of the trigeminal nerve at the anterior portion of the infratemporal fossa. The other patient presented with occipital headaches and hypoglossal nerve palsy. This patient was found to have a calcified lesion in the posterior fossa, which eroded the left occipital condyle.

Conclusion Calcifying pseudoneoplasms are benign, slow-growing masses that are apparently cured by gross total resection. Even with incomplete tumor resection, the prognosis is considered to be favorable. We advocate a minimally invasive surgical resection of such tumors involving the cranial nerves.

Calcifying pseudoneoplasm of the cerebellopontine angle: case report

BACKGROUND AND IMPORTANCE

Calcifying pseudoneoplasms are rare tumors of the neuraxis. To our knowledge, this is only the second reported case in the literature of calcifying pseudoneoplasm of the cerebellopontine angle. The etiology and natural history of these neoplasms are not well understood. This case report provides a thorough review of the histology and potential origins of calcifying pseudoneoplasm.

CLINICAL PRESENTATION

A 34-year-old previously healthy man presented with a 6-month history of progressive worsening headaches, fatigue, tinnitus, dizziness, and blurry vision. Neurological examination was notable for tongue deviation, tongue atrophy, and left uvula deviation. Computed tomography (CT) scanning showed a 3.3 × 3.5 cm densely calcified posterior fossa mass appearing to arise from the occipital bone. Magnetic resonance imaging (MRI) revealed a 4.3 × 2.9 × 2.9 cm left posterior fossa enhancing mass with the margin tip from the left occipital condyle. A transcondylar approach was used to resect the lesion. The mass was found to have eroded through the bone into the foramen magnum. Histopathological examination confirmed the diagnosis of calcifying pseudoneoplasm of the cerebellopontine angle.

CONCLUSION

Calcifying pseudoneoplasms should be considered in the differential diagnosis of calcified cerebellopontine angle tumors. Histopathologic diagnosis is extremely important in the characterization of these lesions in order to direct the course of appropriate management. An inaccurate diagnosis of a malignant tumor can result in potentially harmful and unnecessary therapies, as prognosis for these lesions is generally favorable.

Simultaneously occurring tumours within the same cerebello-pontine angle: refining literature definitions and proposal for classification

We report on an unusual case of a patient, not affected by neurofibromatosis, harbouring two radiologically spatially contiguous tumours within the same cerebello-pontine angle. Pathological findings were consistent with the diagnosis of two spatially distinct primary tumours, namely a meningioma and a schwannoma. We proposed a classification of tumours occurring at the same location consistent with the different spatial arrangement and histological nature of these conditions. The correct classification of these nosological entities will allow further more accurate evaluations of these cases in order to clarify the pathogenesis, prognosis and best treatment of each one.

The 2007 WHO classification of tumors of the nervous system: controversies in surgical neuropathology

Controversy surrounds the recent 2007 WHO Classification of Tumours of the Nervous System. A number of nosologic issues remain to be resolved, some a reflection of conceptual disagreement, others the result of inadequate data to permit their definitive resolution. Among these and discussed herein are (i) the nosologic place of highly anaplastic oligoastrocytic tumors, (ii) the forms and significance of microvascular changes in high-grade gliomas, (iii) the makeup of the glioneuronal tumors category, (iv) the subclassification of pineal parenchymal tumors of intermediate type, and (v) the classification of principle forms of mesenchymal neoplasms, specifically hemangiopericytoma and solitary fibrous tumor. These issues and others are the substance of this and an upcoming companion article.