Skull Base Tumors and Tumor-Like Lesions: A Pictorial Review

Rosai-Dorfman sphenoorbital histiocytosis with intraparenchymal invasion: Do we have to consider this skull base pathology as a malignant disease?

Background

Rosai-Dorfman disease (RDD) is a rare type of histiocytosis that can manifest with diverse symptoms. It usually presents with systemic involvement, and only a few cases have been reported at the level of the skull base. RDD typically follows a benign course during the progression of the disease. In this particular case reported, after the skull base invasion, the disease started to infiltrate the brain parenchyma. Our objective for this case report was to present this particular progression pattern and the nuances of its surgical treatment. In addition, a revision of the current literature was performed about skull base RDD with intracranial invasion and brain parenchyma infiltration not previously described.

Case Description

We are presenting the case study of a 57-year-old male patient who was experiencing severe headaches and an increase in volume in the right fronto-orbital region. On clinical examination, no neurologic clinical symptoms were observed. Contrast computed tomography and magnetic resonance imaging showed a tumor mass that affected the right orbit, frontal paranasal sinus, greater sphenoid wing, and right frontal lobe with moderate adjacent brain edema. The patient underwent surgery using an extended pterional approach with intracranial, orbital decompression, and frontal sinus cranialization, accompanied by frontal lobe tumor resection. Neuropathologic diagnosis revealed a Rosai-Dorfman histiocytosis disease.

Conclusion

The etiopathogenesis of RDD is still not completely understood. The current literature considers this disease to have a predominantly benign course. Nevertheless, as we have shown in this case, it may, in some cases, present direct parenchymal invasion. We consider that prompt surgical treatment should be ideal to avoid the local and systemic progression of the disease.

Preoperative Diagnosis of a Central Skull Base Giant Schwannoma From Tumoral Microhemorrhages Visualized on Susceptibility-Weighted Imaging

A 64-year-old female presented with extensive osseous erosion of the central skull base from a large tumor, which was evaluated with a combination of CT and MRI. Susceptibility-weighted imaging (SWI) aided the correct preoperative diagnosis of giant skull base schwannoma by demonstrating intratumoral microhemorrhages, later confirmed on histology. Other imaging features on CT and MRI were not helpful to identify the schwannoma in this case.

Giant Cell Tumor of the Central Skull Base

Giant cell tumor (GCT) of bone is an uncommon indolent tumor, typically occurring in the meta-epiphysis of long bones in young adults. GCT arising in the clivus is exceedingly rare, and even more uncommon in the pediatric population. We present a case of a 13-year-old patient diagnosed with a large GCT in the clivus. Initial clinical and radiographic findings were suspicious for a GCT, although other more common skull base tumors were also considered in the differential diagnosis. Certain key radiographic features suggested the diagnosis of a GCT, including the low T2 signal within the mass on MRI and the T2 hypointense rim corresponding with a cortical shell present on CT. An endoscopic biopsy confirmed the diagnosis. This report highlights the unique diagnostic challenges and broad differential in this case while underscoring the role of imaging in detection and precise anatomic delineation that helps guide therapeutic decisions and improve patient prognosis.

Non-chordomatous clival bony tumors: A rare experience and systematic literature review

BACKGROUND

Non-chordomatous bony tumors of the clivus are extremely rare. Site, extent, and aggressiveness of tumor limits the extent of resection. It poses challenge to the neurosurgeons due to the complexity of anatomy. There is paucity of literature exclusively on non-chordomatous bone tumors of the clivus in young adults.

OBJECTIVES

To analyze the clinical presentation, imaging findings, surgical approach, complications, and outcome of primary clival bony tumors in young adults.

METHODS

We retrospectively reviewed children and young adults with primary clival bony tumors excluding chordoma who underwent surgical resection between years 2010 and 2023 in our center. We analyzed the demographic details, imaging findings, operative variables, perioperative complications, length of stay, complications, and outcome at latest follow-up.

RESULTS

The mean age was 17.5 ± 1.73 years (range 16 to 19 years). Headache was the presenting complaint in all four patients (100%). The mean duration of symptom was 7.25 ± 3.2 months (range 5 to 12 months). The tumor was localized in clivus in all four patients (100%). The mean length of stay in hospital was 30.5 ± 13.48 days (range 11 to 40 days). All patients underwent surgical treatment. Surgical approaches used were anterior approach in four patients (100%). Gross total excision was performed in one patient (25%), sub-total excision was performed in two patients (50%), and tumor decompression was performed in one patient (25%). Of these, three were designated as having benign tumors and one had a malignant tumor. There was no perioperative mortality. There was one mortality (25%) on 2 months follow-up due to tumor progression. Three patients (75%) had improved symptomatically at latest follow-up. Two patients (50%) received adjuvant chemoradiotherapy. The mean follow-up was 38 ± 39.29 months (range 2 to 72 months).

CONCLUSION

Non-chordomatous bony tumors of the clivus are rare and often underestimated. Surgery is the treatment of choice. Tumor consistency and adhesion to critical neurovascular structures precludes gross total resection. Various approaches are in the armamentarium. Approach to be decided based on the expertise of the neurosurgeon to achieve safe maximal resection. Multidisciplinary approach is mandatory for streamlined management. Adjuvant therapy is decided based on the residual tumor following surgery.

[Simultaneous occurrence of facial neurinoma in internal auditory canal and middle ear paraganglioma in patient. Unusual combination and difficult surgical task]

CLINICAL CASE

The 59-year-old patient complained of hearing loss on the left, ear murmur for a long time, periodic pain and discomfort in the left ear, dizziness for 6 months. She was found to have concurrent vestibular schwannoma in the internal auditory canal and temporal bone paraganglioma. Both tumors were removed in one operation. The schwannoma was removed by translabirinth access due to preoperative deafness, while the glomus tumor was removed during this access. Postoperative biopsy showed the presence of two unrelated diseases: paraganglioma (ICD-0 code 8690/3) and schwannoma (ICD-0 code 9560/0).

Clinical situations for which 3D printing is considered an appropriate representation or extension of data contained in a medical imaging examination: neurosurgical and otolaryngologic conditions

BACKGROUND

Medical three dimensional (3D) printing is performed for neurosurgical and otolaryngologic conditions, but without evidence-based guidance on clinical appropriateness. A writing group composed of the Radiological Society of North America (RSNA) Special Interest Group on 3D Printing (SIG) provides appropriateness recommendations for neurologic 3D printing conditions.

METHODS

A structured literature search was conducted to identify all relevant articles using 3D printing technology associated with neurologic and otolaryngologic conditions. Each study was vetted by the authors and strength of evidence was assessed according to published guidelines.

RESULTS

Evidence-based recommendations for when 3D printing is appropriate are provided for diseases of the calvaria and skull base, brain tumors and cerebrovascular disease. Recommendations are provided in accordance with strength of evidence of publications corresponding to each neurologic condition combined with expert opinion from members of the 3D printing SIG.

CONCLUSIONS

This consensus guidance document, created by the members of the 3D printing SIG, provides a reference for clinical standards of 3D printing for neurologic conditions.

Correlation Analysis on Anatomical Variants of Accessory Foramina in the Sphenoid Bone for Oncological Surgery

The sphenoid bone presents several anatomical variations, including accessory foramina, such as the foramen meningo-orbitale, the foramen of Vesalius, the canaliculus innominatus and the palatovaginal canal, which may be involved in tumor invasion or surgery of surrounding structures. Therefore, clinicians and surgeons have to consider these variants when planning surgical interventions of the cranial base. The prevalence of each variant is reported in the published literature, but very little information is available on the possible correlation among different variants. Here, 300 CT scans of patients (equally divided among males and females) were retrospectively assessed to investigate the presence of the foramen meningo-orbitale, the foramen of Vesalius, the canaliculus innominatus and the palatovaginal canal. Possible differences in the prevalence of each accessory foramen according to sex were assessed, as well as possible correlations among different variants through the Chi-square test (p < 0.01). Overall, the prevalence of the foramen meningo-orbitale, the foramen of Vesalius, the canaliculus innominatus and the palatovaginal canal was 30.7%, 67.7%, 14.0% and 35.3%, respectively, without any difference according to sex (p > 0.01). A significant positive correlation was found between the foramen of Vesalius and canaliculus innominatus, both in males and in females (p < 0.01). In detail, subjects with canaliculus innominatus in 85.7-100.0% of cases also showed the foramen of Vesalius, independently from sex and side. The present study provided novel data about the prevalence of four accessory foramina of the sphenoid bone in an Italian population, and a correlation between the foramen of Vesalius and the canaliculus innominatus was found for the first time. As these accessory foramina host neurovascular structures, the results of this study are thus useful for appropriate planning surgical procedures that are tailored to the anatomical configuration of the patient and for improving techniques to avoid accidental injuries in cranial base surgery. Knowledge of the topography, frequencies and the presence/absence of these additional foramina are pivotal for a successful procedure. Clinicians and surgeons may benefit from these novel data for appropriate recognition of the variants, decision-making, pre-operative and treatment planning, improvement of the procedures, screening of patients and prevention of misdiagnosis.

Sphenoid bone localization in the setting of highly aggressive and refractory Multiple Myeloma: A case report

Multiple Myeloma (MM) is the most common primary osseous malignancy in adults, and it mainly affects men aged between 50 and 70 years. Although rare, central nervous system (CNS) involvement in MM is possible, and it has very poor prognosis. Therefore, fast and accurate diagnosis of CNS manifestation of MM is paramount. Here we describe a case of sphenoid bone localization in a patient with highly aggressive and refractory MM.

Imaging of Skull Base Tumors

The skull base provides a platform for supporting the brain while serving as a conduit for major neurovascular structures. In addition to malignant lesions originating in the skull base, there are many benign entities and developmental variants that may simulate disease. Therefore, a basic understanding of the relevant embryology is essential. Lesions centered in the skull base can extend to the adjacent intracranial and extracranial compartments; conversely, the skull base can be secondarily involved by primary extracranial and intracranial disease. CT and MRI are the mainstay imaging methods and are complementary in the evaluation of skull base lesions. Advances in cross-sectional imaging have been crucial in the management of patients with skull base pathology, as this represents a complex anatomical area that is hidden from direct clinical exam. Furthermore, the clinician must rely on imaging studies for therapy planning and to monitor treatment response. It is crucial to have a thorough understanding of skull base anatomy and its various pathologies, as well as to recognize the appearance of treatment-related changes. In this review, we aim to describe skull base tumors and tumor-like lesions in an anatomical compartmental approach and present imaging methods that aid in diagnosis, management, and follow-up.

AS. Clival and Paraclival Lesions: A Pictorial Review

The clivus is a midline anatomical structure in the central skull base. It is affected by a wide range of non-neoplastic, benign and malignant pathologies, some of which typically affect the clivus because of its strategic location and embryological origins. Clival lesions may often be asymptomatic with occasional complaints like headache or cranial neuropathy in few. Cross-sectional imaging techniques, namely, computed tomographic scan and magnetic resonance imaging, thus, play a key role in approximating to the final diagnosis and estimating the disease extent. In this article, we highlight the important imaging features of various clival and paraclival pathologies to facilitate effective diagnosis, therapeutic planning, and management.

Intraosseous schwannoma in the clivus mimicking chordoma treated with endoscopic endonasal surgery: A case report

Background:

Intraosseous schwannomas are extremely rare and they have not yet been reported to occur in the clivus. We report a schwannoma in the clivus mimicking chordoma and review intraosseous schwannomas of the skull.

Case Description:

A 62-year-old man presented with gradually worsening hoarseness with dysphagia and atrophy of the left tongue, trapezius muscle, and sternocleidomastoid muscle. Magnetic resonance imaging showed that the tumor was mainly located in the clivus, and a computed tomography (CT) scan revealed an osteolytic lesion with expansion of the clivus and preservation of the bony cortex. Endoscopic endonasal surgery was performed to diagnose and treat symptoms. The tumor was subtotally removed without any complications. The histopathological findings revealed typical schwannoma, which showed Antoni A and Antoni B patterns positive for S100 protein. Based on the preoperative imaging, intraoperative and histopathological findings, the tumor was considered to be an intraosseous schwannoma in the clivus, and no recurrence was observed after 1 year of postoperative follow-up.

Conclusion:

Even though the intraosseous schwannoma in the clivus is uncommon, it should be considered as a differential diagnosis if an expansive lesion without destruction of the cortical bone is shown on CT as well as iso-hyperintensity on T2-weighted magnetic resonance imaging.

Chordoma at the skull base, spine, and sacrum: A pictorial essay

Chordomas are rare tumors believed to be arising from the notochord remnant in the axial skeleton. Diagnosis is often difficult since they show overlapping imaging features with other more common disease including metastases. Since individualized papers are only discussing the imaging features at different locations, the aim of this pictorial review is to have a comprehensive review on the common imaging findings of chordomas along the entire neuroaxis with a series of pathological proven cases in a local tertiary hospital in Hong Kong.

Intraosseous Venous Malformations of the Head and Neck

Intraosseous venous malformations represent a subtype of venous vascular malformations that arise primarily in bone. In the head and neck, intraosseous venous malformations are most frequently found in the skull, skull base, and facial skeleton, with location at the geniculate ganglion of the facial nerve perhaps the most widely recognized. These non-neoplastic lesions are characterized by dilated venous channels with characteristic internal bony spicules on CT but may present with a more complex appearance on MR imaging and may share features with more aggressive lesions. Further confounding the imaging-based diagnosis of intraosseous venous malformation is the frequent misrepresentation of these lesions as hemangiomas in the radiology and clinical literature, as well as in daily practice. Because most intraosseous venous malformations can be left alone, their correct diagnosis may spare a patient unnecessary concern and intervention.

A practical overview of CT and MRI features of developmental, inflammatory, and neoplastic lesions of the sphenoid body and clivus

The sphenoid bone is an unpaired bone that contributes to the formation of the skull base. Despite the enormous progress in transnasal endoscopic visualisation, imaging techniques remain the cornerstones to characterise any pathological condition arising in this area. In the present review, we offer a bird's-eye view of the developmental, inflammatory, and neoplastic alterations affecting the sphenoid body and clivus, with the aim to propose a practical diagnostic aid for radiologists based on clinico-epidemiological, computed tomography, and magnetic resonance imaging features.

Rapid Automated Analysis of Skull Base Tumor Specimens Using Intraoperative Optical Imaging and Artificial Intelligence

BACKGROUND

Accurate specimen analysis of skull base tumors is essential for providing personalized surgical treatment strategies. Intraoperative specimen interpretation can be challenging because of the wide range of skull base pathologies and lack of intraoperative pathology resources.

OBJECTIVE

To develop an independent and parallel intraoperative workflow that can provide rapid and accurate skull base tumor specimen analysis using label-free optical imaging and artificial intelligence.

METHODS

We used a fiber laser-based, label-free, nonconsumptive, high-resolution microscopy method (<60 seconds per 1 × 1 mm2), called stimulated Raman histology (SRH), to image a consecutive, multicenter cohort of patients with skull base tumor. SRH images were then used to train a convolutional neural network model using 3 representation learning strategies: cross-entropy, self-supervised contrastive learning, and supervised contrastive learning. Our trained convolutional neural network models were tested on a held-out, multicenter SRH data set.

RESULTS

SRH was able to image the diagnostic features of both benign and malignant skull base tumors. Of the 3 representation learning strategies, supervised contrastive learning most effectively learned the distinctive and diagnostic SRH image features for each of the skull base tumor types. In our multicenter testing set, cross-entropy achieved an overall diagnostic accuracy of 91.5%, self-supervised contrastive learning 83.9%, and supervised contrastive learning 96.6%. Our trained model was able to segment tumor-normal margins and detect regions of microscopic tumor infiltration in meningioma SRH images.

CONCLUSION

SRH with trained artificial intelligence models can provide rapid and accurate intraoperative analysis of skull base tumor specimens to inform surgical decision-making.

Racial disparity in recommendation for surgical resection of skull base chondrosarcomas: A Surveillance, Epidemiology, and End Results (SEER) analysis

INTRODUCTION

There is increased appreciation of racial disparities in the delivery of neurosurgical care. Here, we explore whether race influences surgical recommendations in the management of skull base chondrosarcomas.

METHODS

We identified 493 patients with skull base chondrosarcoma using the Surveillance, Epidemiology, and End Results (SEER) registry (November 2017 submission). Regression analyses were performed to identify demographic variables associated with recommendation against surgery. Univariate and multivariate cox proportional hazards models were used for survival analysis.

RESULTS

In a univariate analysis, we found that the African-American race was associated with an increased likelihood of surgeon recommendation against surgery (OR = 4.416, 95% CI = 1.893-10.302, p = 0.001). This association remained robust in the multivariate model that controlled for other covariates, including age of diagnosis (OR = 5.091, 95% CI = 2.127-12.187, p < 0.001). For patients who received a recommendation against surgery, the likelihood of dying from non-chondrosarcoma causes was comparable between Caucasian and African-American patients, suggesting that the prevalence and severity of medical conditions that increase the risk of death were comparable between these cohorts (HR = 0.466, 95% CI = 0.057-3.802, p = 0.475). The likelihood of dying from chondrosarcoma was comparable between Caucasian and African-American patients who underwent surgery (HR = 0.982, 95% CI = 0.353-2.732, p = 0.973), suggesting absence of race-specific surgical benefits.

CONCLUSION

We identified a racial disparity against African-Americans in recommendations for surgical resection of skull base chondrosarcomas.

Olfactory Neuroblastoma Managed with Endoscopic Sinus Surgery

Olfactory neuroblastoma (ONB) or esthesioneuroblastoma is a rare malignancy of the nose and paranasal sinuses that originates from the upper nasal vault. We report a rare case of ONB in a 27-year-old female patient with a 2-year history of nasal obstruction, sneezing, nasal discharge, and left eye protrusion. The patient was successfully treated with endoscopic sinus surgery and adjuvant radiotherapy (RT) with 5-year follow-up duration. Studying ONB cases is of great importance due to its rare occurrence, and the lack of literature regarding its management often creates a dilemma leading to nonstandardized treatment methods. Prolonged surveillance is essential due to its late recurrence and endoscopic resection followed by adjuvant RT, which may be a feasible and effective treatment. There is no single case of ONB published yet in Saudi Arabia, and to our knowledge, this is the first case report.

Endoscopic endonasal resection of sinonasal teratocarcinosarcoma with intracranial breakthrough: illustrative case

BACKGROUND

Teratocarcinosarcoma traversing the anterior skull base is rarely reported in literature. The heterogenous and invasive features of the tumor pose challenges for surgical planning. With technological advancements, the endoscopic endonasal approach (EEA) has been emerging as a workhorse of anterior skull base lesions. To date, no case has been reported of EEA totally removing teratocarcinosarcomas with intracranial extensions.

OBSERVATIONS

The authors provided an illustrative case of a 50-year-old otherwise healthy man who presented with left-sided epistaxis for a year. Imaging studies revealed a 31 × 60-mm communicating lesion of the anterior skull base. Gross total resection via EEA was achieved, and multilayered skull base reconstruction was performed.

LESSONS

The endoscopic approach may be safe and effective for resection of extensive teratocarcinosarcoma of the anterior skull base. To minimize the risk of postoperative cerebrospinal fluid leaks, multilayered skull base reconstruction and placement of lumbar drainage are vitally important.

Central Skull Base Anatomy and Pathology: A Review

The central skull base is an anatomically complex region of the head and neck which hosts a variety of neoplastic, vascular, infectious, inflammatory, and developmental pathologies. Evaluation of its intricate anatomy requires dedicated and complementary imaging modalities of MRI and CT. This article will provide a brief review of the anatomy of the central skull base, followed by an overview of common pathologies encountered in this region and their characteristic radiological characteristics.

Cavernous sinus lesions

The cavernous sinus is a complex structure susceptible to a wide variety of vascular, neoplastic and inflammatory pathologies. Vascular pathologies include ICA aneurysms, carotid-cavernous fistulas, cavernous sinus thrombosis, and cavernous hemangioma. Neoplasms that involve the cavernous sinus include pituitary adenoma, meningioma, schwannoma, lymphoma, perineural tumor spread, metastases, and direct tumor invasion. Infectious and inflammatory diseases include Tolosa-Hunt syndrome, sarcoidosis, granulomatosis with polyangiitis, IgG-4 related disease and invasive fungal infections. In this article, we review the clinical and imaging findings of a number of pathologies involving the cavernous sinus, focusing on key features that can narrow the differential diagnosis and, in some cases, support a particular diagnosis.

Ophthalmic and orbital considerations in the evaluation of skull base malignancies

INTRODUCTION

The orbital contents, afferent and efferent visual pathways, and the cranial nerves involved in eye movement, corneal sensation and eyelid closure traverse the skull base, a region bounded by the intracranial cavity, the paranasal sinuses, and the deep spaces of the face and head. As such, tumors from above or below have potential to affect some aspect of the visual system.

METHODS

We discuss here the clinical ophthalmologic and orbital considerations in the evaluation of patients with these tumors, as well as the ophthalmic sequelae of treatment with radiation or surgery (or both). And for the surgeon, we discuss the ophthalmic and orbital considerations in surgical planning, the role of the orbital surgeon in skull base surgery, and briefly discuss transorbital approaches to the skull base.

RESULTS AND CONCLUSION

Ophthalmic and orbital dysfunction may be the main source of disability in patients with skull base malignancy; it is thus incumbent on those who manage patients with tumors of this region to be aware of the ophthalmic, neuro-ophthalmic and orbital manifestations, so as to best tailor therapy and monitor treatment outcomes.

Untargeted Contrast-Enhanced Ultrasound Versus Contrast-Enhanced Computed Tomography: A Differential Diagnostic Performance (DDP) Study for Kidney Lesions

OBJECTIVES

Histopathology is the 'gold standard' for diagnosing renal cell carcinoma but is limited by sample size. Contrast-enhanced ultrasound can differentiate malignant and benign lesions, but the Chinese guidelines on the management of renal cell carcinoma do not include this method. The purpose of this study was to compare the diagnostic parameters of contrast-enhanced ultrasound against those of contrast-enhanced computed tomography for detecting kidney lesions, with histopathology considered the reference standard.

METHODS

Patients with suspected kidney lesions from prior grayscale ultrasonography and computed tomography were included in the analysis (n=191). The contrast-enhanced ultrasound, contrast-enhanced computed tomography, and histopathology data were collected and analyzed. A solid, enhanced mass was considered a malignant lesion, and an unenhanced mass or cyst was considered a benign lesion. The Bosniak criteria were used to characterize the lesions.

RESULTS

Contrast-enhanced ultrasound and contrast-enhanced computed tomography both detected that 151 patients had malignant tumors and 40 patients had benign tumors. No significant differences in the tumors and their subtypes were reported between contrast-enhanced ultrasound and histopathology (p=0.804). Chromophobe renal cell carcinoma was detected through contrast-enhanced computed tomography (n=1), but no such finding was reported by contrast-enhanced ultrasound. A total of 35 cases of papillary renal cell carcinoma were reported through contrast-enhanced ultrasound while 32 were reported through histopathology.

CONCLUSIONS

Contrast-enhanced ultrasound might be safe and as accurate as histopathology in diagnosing kidney lesions, especially renal cell carcinoma. Additionally, this study provides additional information over histopathology and has an excellent safety profile.

LEVEL OF EVIDENCE

III.

[Malignant tumors of the skull base]

Malignant skull base tumors consist of a heterogeneous group of malignancies that can be divided into primary and secondary (metastatic) skull base tumors. In addition, according their anatomical location, they can be further divided into tumors of the anterior, middle, or posterior cranial fossa. Although malignant skull base tumors do not rigorously respect anatomical borders, their anatomical occurrence can potentially be helpful for possible differential diagnosis. This article is focused on the most common malignant tumors of the skull base and their imaging and clinical presentations.

Fossa navicularis in a pediatric patient: anatomical skull base variant with clinical implications

The fossa navicularis is an anatomical variant of the skull base thought to be a rare finding. It represents a bony depression in the skull base. The authors here report the case of a fossa navicularis magna in a 9-year-old female who had been treated for recurrent episodes of meningitis.A literature review was also done to highlight the unique features and clinical importance of this distinctive radiological skull base finding. The literature search covered papers from the 19th century up to 2018. Earlier authors described "fossa navicularis" as a very rare skull base finding. So far, only three cases of fossa navicularis with associated clival or intracranial infection have been reported in the literature. This is the fourth reported case, and the defect was closed endoscopically via a transnasal route. This morphological skull base anomaly should be considered in the differential diagnoses for an unexplained skull base infective pathology.Skull base surgeons should be aware of the existence of the fossa navicularis because of its clinical importance in rendering a prompt diagnosis and appropriate treatment.