DEK::AFF2 Carcinoma of the Sinonasal Tract and Skull Base: A Comprehensive Review.

DEK::AFF2 carcinoma is an emerging entity of the sinonasal tract and skull base, commonly exhibiting exophytic and endophytic papillary growth, complex anastomosing trabeculae, monotonous cytomorphology, acantholytic change, and tumor-infiltrating neutrophils. A subset displays overt infiltration and high-grade features akin to non-keratinizing squamous cell carcinoma. Glandular differentiation may also be rarely present. The tumor shows frequent local recurrence and occasional distant metastasis. An accurate diagnosis requires the recognition of these key histologic features, followed by molecular confirmation. Recently, AFF2 immunohistochemistry has been demonstrated to be a sensitive and specific ancillary marker. This comprehensive review summarizes the current understanding of DEK::AFF2 carcinoma.

Deep learning model using planar whole-body bone scintigraphy for diagnosis of skull base invasion in patients with nasopharyngeal carcinoma.

PURPOSE: This study assesses the reliability of deep learning models based on planar whole-body bone scintigraphy for diagnosing Skull base invasion (SBI) in nasopharyngeal carcinoma (NPC) patients. METHODS: In this multicenter study, a deep learning model was developed using data from one center with a 7:3 allocation to training and internal test sets, to diagnose SBI in patients newly diagnosed with NPC using planar whole-body bone scintigraphy. Patients were diagnosed based on a composite reference standard incorporating radiologic and follow-up data. Ten different convolutional neural network (CNN) models were applied to both whole-image and partial-image input modes to determine the optimal model for each analysis. Model performance was assessed using the area under the receiver operating characteristic curve (AUC), calibration, decision curve analysis (DCA), and compared with expert assessments by two nuclear medicine physicians. RESULTS: The best-performing model using partial-body input achieved AUCs of 0.80 (95% CI: 0.73, 0.86) in the internal test set, 0.84 (95% CI: 0.77, 0.91) in the external cohort, and 0.78 (95% CI: 0.73, 0.83) in the treatment test cohort. Calibration curves and DCA confirmed the models' excellent discrimination, calibration, and potential clinical utility across internal and external datasets. The AUCs of both nuclear medicine physicians were lower than those of the best-performing deep learning model in external test set (AUC: 0.75 vs. 0.77 vs. 0.84). CONCLUSION: Deep learning models utilizing partial-body input from planar whole-body bone scintigraphy demonstrate high discriminatory power for diagnosing SBI in NPC patients, surpassing experienced nuclear medicine physicians.

The impact of arachnoid structures on skull-base meningioma surgical management: a radiological analysis and narrative review.

The presence of intact arachnoid membranes between skull base meningiomas and critical neurovascular structures is crucial for predicting surgical outcomes, understanding tumor development and growth, and planning the feasibility of tumor resection or the need for adjuvant treatments. While neurosurgeons often utilize the subarachnoid cisterns to enhance access to these tumors and facilitate their removal, a comprehensive review aimed at health professionals involved in the diagnosis and treatment of this complex pathology, including radiologists, neurologists, oncologists, ophthalmologists, and neurosurgeons is still lacking. This study aims to summarize the interaction between skull base meningiomas, subarachnoid cisterns, and arachnoid membranes, emphasizing their significance in both the diagnosis and treatment of this pathology. By conducting a thorough radiological assessment of skull base meningiomas, correlating these findings with intraoperative observations, and reviewing relevant literature, we summarize the critical relationship between skull base meningiomas and the surrounding subarachnoid spaces. We concisely describe how arachnoid structures influence tumor growth and interaction with neurovascular elements. We advocate for the inclusion of tumor-arachnoid relationships in the medical literature concerning the treatment of these tumors. A better understanding and description of the interaction between tumors and neurovascular structures will aid in planning and attempting safer treatments, minimizing surgical risks, predicting potential tumor progression, and the need for adjuvant treatments.

Comparative overall survival analysis of chordomas of the base of the skull from the Surveillance, Epidemiology, and End Results (SEER) program between 2000 and 2020.

Chordomas of the skull base are rare, slow growing, locally invasive cancers with limited long-term survival analysis reported in the literature. We seek to provide comparative survival analysis of patients on a long-term (20-year) basis using population-level data. The Surveillance, Epidemiology, and End Results (SEER) program was queried for cases of chordoma relegated to the base of the skull, diagnosed between 2000 and 2020. Demographic, disease, and treatment information were analyzed using Cox proportional hazards and log-rank comparisons. 630 patients with chordoma of the skull base were identified. Age ≤ 49 years at diagnosis was associated with increased five-, 10-, and 20-year overall survival (hazard ratio (HR) = 0.39, 0.33, and 0.30, respectively; p < 0.001 for all). Treatment with surgery and adjuvant radiotherapy was associated with increased five-, 10-, and 20-year survival (HR = 0.71, 0.79, and 0.79, respectively; p < 0.001 for all). On univariate analysis, widowed patients had decreased survival (20-year overall survival = 34.8% [15.3%-34.8%] compared to married patients (74.4% [68.1%-80.8%]. Surgery remains the primary treatment associated with increased survival among patients with chordoma of the skull base, with adjuvant radiotherapy serving a complimentary role. Demographic factors such as marital status are also associated with changes in survival.

Proteogenomic characterization of skull-base chordoma.

Skull-base chordoma is a rare, aggressive bone cancer with a high recurrence rate. Despite advances in genomic studies, its molecular characteristics and effective therapies remain unknown. Here, we conduct integrative genomics, transcriptomics, proteomics, and phosphoproteomics analyses of 187 skull-base chordoma tumors. In our study, chromosome instability is identified as a prognostic predictor and potential therapeutic target. Multi-omics data reveals downstream effects of chromosome instability, with RPRD1B as a putative target for radiotherapy-resistant patients. Chromosome 1q gain, associated with chromosome instability and upregulated mitochondrial functions, lead to poorer clinical outcomes. Immune subtyping identify an immune cold subtype linked to chromosome 9p/10q loss and immune evasion. Proteomics-based classification reveals subtypes (P-II and P-III) with high chromosome instability and immune cold features, with P-II tumors showing increased invasiveness. These findings, confirmed in 17 paired samples, provide insights into the biology and treatment of skull-base chordoma.

Impact of extent of resection and adjuvant radiation therapy in the progression free survival in patients with spheno-orbital meningioma.

BACKGROUND: Spheno-orbital meningiomas (SOM) are known to invaded critical skull base areas. The authors report a series of WHO I SOM, propose a subclassification of this tumor according to its extension to critical positions and analyze the impact of extent of resection and the role of stereotactic radiotherapy in tumor recurrence. METHODS: A prospective maintained university medical center registry was utilized to undertake a retrospective review of patients operated with WHO I SOM. Details related to critical skull base region's extension (superior orbital fissure, cavernous sinus, orbital apex), extent of resection and adjuvant radiosurgery were collected. Statistical calculations were preformed using IBM SPSS Statistics version 25. A p value < 0.05 was considered significant. Survival analysis was performed using Kaplan-Meier survival analysis and the log rank test. RESULTS: A total of 77 patients operated from 2002 to 2021 were included. There were 65 women (84.4 %) and 12 men (15.6 %). Mean age at surgery was 54.8 years (median 53 years, range 23 - 88). Tumors were defined as local in 28 (35.4 %) and with extension into the skull base critical structures in 51 (64.6 %). GTR was achieved in 35 (44.3 %), STR in 40 (50.6 %), and PR in four (5.1 %). Surgical morbidity was 10 %. There was no surgical mortality. 28 patients with STR or PR were treated with adjuvant radiotherapy. The total length of follow up was a mean of 172.3 months. There were 14 recurrences/progressive growth (17.7 %), 63 patients (79.7 %) had no recurrence/progressive growth, and two patients (2.5 %) were lost to follow-up. PFS was significant statistically different in patients with invasive tumors in whom the extent of resection was subtotal, with a longer PFS in patients that were treated with adjuvant radiotherapy. (P value < 0.001). CONCLUSIONS: SOM could be divided in two groups according to its skull base extension facilitating decision management and outcome prediction. Patients with local WHO I SOM had higher rate of GTR and better PFS than tumors extending to involve critical regions. When STR or PR is achieved postoperative adjuvant radiotherapy is advised if there is evidence of previous tumor growth.

Clival chordomas and chondrosarcomas in Denmark-Outcomes in 33 patients following the national centralization of treatment in 2010.

PURPOSE: This 13-year consecutive case series aims to provide a comprehensive overview of all patients operated for clival chordomas and clival chondrosarcomas in Denmark since the centralization of treatment in 2010, comparing outcomes to international series. METHODS: This was a retrospective review of 33 patients with clival tumors, comprising 22 chordomas and 11 chondrosarcomas, who were treated at Copenhagen University Hospital between years 2010 and 2023. Data were collected from digital patient records and pathology reports. RESULTS: The symptoms leading to diagnosis primarily included double vision, headaches, and dizziness. In general, patients were in good health, with a mean Charlson Comorbidity Index score of 1.6. The complication rate of the index surgery was 51.5%. Adjuvant radiotherapy was applied in 51.5% of the cases. In patients with clival chordomas, the mean age was 51.1 years, ranging from 16 to 83 years. At the time of diagnosis, the mean tumor volume was 20.9 cm3 and the five-year overall survival rates were 79.1% (95% confidence interval (CI): 62.4-100). In patients with chondrosarcomas, the mean age was 48.2 years, ranging from 15 to 76 years. At the time of diagnosis, the mean tumor volume was 22.3 cm3 and the five-year overall survival 90% (95% CI: 73.2-100). CONCLUSION: The centralized treatment of clival tumors in Denmark demonstrates incidence, survival, and complication rates comparable to those found in other international series. Given the variations in treatment strategies, tumor localizations across series, and small sample sizes, the further analysis of larger compiled multicenter datasets for clival tumors could provide more solid evidence regarding the management of these rare tumors.

Genomic profiles and clinical presentation of chordoma.

Chordoma is a rare bone cancer with variable clinical outcomes. Here, we recruited 184 sporadic chordoma patients from the US and Canada and collected their clinical and treatment data. The average age at diagnosis was 45.5 years (Range 5-78) and the chordoma site distribution was 49.2% clivus, 26.2% spinal, and 24.0% sacral. Most patients (97.5%) received surgery as the primary treatment, among whom 85.3% also received additional treatment. Except for the most prevalent cancers like prostate, lung, breast, and skin cancer, there was no discernible enrichment for any specific cancer type among patients or their family members. Among a subset of patients (N = 70) with tumor materials, we conducted omics analyses and obtained targeted panel sequencing and SNP array genotyping data for 51 and 49 patients, respectively. The most recurrent somatic driver mutations included PIK3CA (12%), followed by chromatin remodeling genes PBRM1 and SETD2. Amplification of the 6q27 region, containing the chordoma susceptibility gene TBXT, was detected in eight patients (16.3%). Clival patients appeared to be less likely to carry driver gene mutations, chromosome arm level deletion events (e.g., 5p, 5p, and 9p), or 6q27 amplification compared to sacral patients. After adjusting for age, sex, tumor site, and additional treatment, patients with somatic deletions of 14q (OR = 13.73, 95% CI 1.96-96.02, P = 0.008) and 18p (OR = 13.68, 95% CI 1.77-105.89, P = 0.012) were more likely to have persistent chordoma. The study highlights genomic heterogeneity in chordoma, potentially linked to location and clinical progression.

Stereotactic radio-neurosurgery for jugular foramen schwannomas.

BACKGROUND: Stereotactic radiosurgery (SRS) represents a minimally invasive and valuable alternative for jugular foramen schwannomas (JFS), both as upfront and/or adjuvant treatment (in hybrid approaches). METHODS: We conducted a retrospective review of our cases treated at the Lausanne University Hospital (CHUV) from June 2010 to October 2023. Eleven patients underwent SRS, among whom three had prior surgery, two in our center in the frame of a planned combined approach and one in another center. Two patients received "volume-staged" SRS. The mean age at SRS was 60 years (median 68; range 29-83). Cranial nerve (CN) symptoms were present in six patients, while five were asymptomatic. The mean tumor volume at SRS was 2.1 cc (median 1.2; range 0.068-7.3 cc), with a 12 Gy marginal dose prescribed in all cases. RESULTS: The mean follow-up period was 3.9 years (median 2, range 1-7). Cranial nerve function improved after SRS in six patients, while five remained stable. At the last follow-up, all tumors showed a decrease in volume, except for one patient, who underwent surgery at 18 months after SRS, for volumetric increase at 6 and 12 months, with further XII-th CN palsy and medulla oblongata compression. Although tumor decreased at 18 months, such patient needed microsurgical resection for symptom persistence and was further controlled. The mean tumor volume at 1 year post-SRS was 1.6 cc (median 0.55; range 0.028-7.77 cc), at 2 years was 1.31 cc (median 0.76; range 0.19-5), and at 3 years was 1.32 cc (median 0.59; range 0.23-4.8). No adverse radiation events were observed. CONCLUSIONS: Stereotactic radiosurgery is considered a safe and effective treatment for jugular foramen schwannomas, ensuring high rates of tumor control in all patients over the long term. The cranial nerve function improved after SRS in the 6 patients who had deficits and the other 5 patients who had no deficits remained asymptomatic. For larger tumors, combined/hybrid approaches can be a valuable alternative, to obtain tumor control and to preserve neurological function.

The intrabulbar or extrabulbar growth pattern and its surgical outcomes of jugular foramen paragangliomas.

OBJECTIVE: This study is to define a subclassification system of jugular foramen paragangliomas (JFPs) and to demonstrate corresponding microsurgical outcomes of JFPs. STUDY DESIGN: Retrospective study. SETTING: A single-center study. METHODS: We conducted a retrospective review of the clinical data of 44 patients with JFPs who underwent surgical management. Extrabulbar(Be) tumor and intrabulbar(Bi) tumor are defined based on the growth patterns, receiver operating characteristic (ROC) curves of the imaging profile were generated and was confirmed based on intraoperative findings. Area Under Curve (AUC), accuracy, sensitivity, and specificity for diagnostic imaging were revealed. We also compared the correlation between the two growth patterns with Fisch's classification, blood loss, lower cranial nerves (LCNs) deficit. RESULTS: There are 27 (69%) cases of Bi tumor and 17 (39%) cases of Be tumor. Significant radiomics features between the two growth patterns were demonstrated, ROC curves achieved excellent AUCs for MRI sequences (T1W1 MRI, MR contrast-enhanced sequence, MR complex sequences and MR complex + DSA by 0.833, 0.833, 0.875, 0.944) and had statistically significant in diagnosis of two growth patterns (P<0.05). There was no statistical correlation between growth patterns of JFPs and intra-operative blood loss. Preoperative LCNs deficits and Fisch's classification of tumors were correlated with the growth patterns of JFPs (P < 0.05). CONCLUSION: We proposetd two growth patterns of JFPs in term of the inferior petrous sinus involvement. Identification of Bi or Be growth patterns preoperatively is helpful to design optimal surgical strategies and minimize postoperative complications.

Skull base plasmacytoma in young patients aged below 40 years: Radiological perspectives and clinical outcomes.

BACKGROUND: Plasmacytoma of the skull base is a rare manifestation of plasma cell neoplasm with only a few cases documented in literature involving young adults. Plasmacytoma can be an isolated solitary lesion or a secondary manifestation of multiple myeloma (MM). In this study, we report the clinical and radiological characteristics, management, and outcomes of patients under the age of 40 who presented with skull base plasmacytoma and associated neurological manifestations. Additionally, we share our experience in treating a rare case of skull base plasmacytoma diagnosed during pregnancy, in which the patient exhibited a favorable response to myeloma treatment initiated after delivery. CASE SERIES: Four patients were identified, comprising one pregnant female and three male patients, with a median age of 36 years (range 33-37 years). The main presenting symptoms were headache, dizziness, and cranial nerve palsy. All patients received underwent systemic myeloma therapy and radiotherapy with three patients also underwent autologous stem cell transplantation (ASCT). Notably, all patients achieved complete remission. CONCLUSION: Skull base plasmacytoma represents a rare manifestation of plasma cell neoplasms, underscoring the importance of considering it in the differential diagnosis of skull base lesions to ensure early intervention and avoid potential serious complications. Throughout our series, the cornerstone of therapy involved radiotherapy, systemic myeloma therapy, and ASCT, all of which elicited a favorable response in every case.

Full Endoscopic Transcranial Resection of Meningiomas.

OBJECTIVE: Tumors of the skull base can be accessed through different routes. Recent advantages in minimally invasive techniques have shown that very different routes can be applied for optimal tumor resection depending on the technical equipment, the surgeon's preference, and the individual anatomy of the pathology. Here, the authors present their technique for pure endoscopic transcranial tumor resection in meningiomas. METHODS: Out of the cases of the Department of Neurosurgery, Homburg Saar Germany of the last 10 years, all endoscopic procedures for meningiomas were analyzed. Particular attention was given to evaluating the peculiarities of those meningiomas that were treated purely endoscopically. RESULTS: While the endoscope was used in a large number of skull base meningiomas in endonasal approaches or for endoscopic inspection in transcranial skull base surgery, only a small number of meningiomas was selected for a purely endoscopically performed resection. The characteristics of these cases were rather a small lesion, straight access, and a keyhole position of the craniotomy. A complete resection of the tumor was achieved in all cases. Conversion to the microscope was not necessary in any case. There were no technical issues or complications associated with a fully endoscopic resection. DISCUSSION: The endoscope is a valuable tool for visualization in meningioma surgery. In most cases, it is applied for an endonasal route or for endoscopic inspection in transcranial microsurgical cases. However, small to medium-sized meningiomas that can be accessed through the keyhole approach are good candidates for pure endoscopic resection. Because of the very high magnification and the minimally invasive nature of this approach, it should be considered more frequently in suitable lesions.

Fully Endoscopic Supraorbital Approach for Anterior Cranial Base Meningiomas.

BACKGROUND: Anterior cranial base meningiomas include those meningiomas originating from the tuberculum sellae, the planum sphenoidale, or the olfactory groove, with surgical excision being the main treatment modality for these tumors. Conventional microscopic and endoscope-assisted versions of the supraorbital keyhole approach via an eyebrow incision emerged into minimally invasive options that are frequently utilized nowadays for treating these tumors. At the early attempts of endoscope-assisted cranial surgery, it was noted that rigid endoscopes enabled overcoming the problem of suboptimal visualization when small exposures are used. The technical specifications and design of the currently available rigid endoscopes are associated with a group of unique features that define the endoscopic view and lay the basis for its superiority over the microscopic view during brain surgery. Notwithstanding, the fully endoscopic or endoscope-controlled version of the supraorbital keyhole approach is not routinely practiced by neurosurgeons, with few series published so far. In this chapter we elaborate on the surgical technique and nuances of the fully endoscopic supraorbital approach for anterior cranial base meningiomas. METHODS: From a prospective database of endoscopic procedures maintained by the senior author, clinical data, imaging studies, operative charts, and videos of cases undergoing fully endoscopic excision of anterior cranial base meningiomas via supraorbital approach were retrieved and analyzed. The pertinent literature was also reviewed. RESULTS: The surgical technique of the fully endoscopic supraorbital approach for anterior cranial base meningiomas was formulated. CONCLUSION: The fully endoscopic supraorbital approach for anterior cranial base meningiomas has many advantages over the conventional procedures. In our hands, the technique has proven to be feasible, efficient, and minimally invasive with excellent results.

[Jugular Foramen, Foramen Magnum Meningiomas].

The jugular foramen, also known as the foramen magnum, is a highly intricate region of the skull base through which numerous critical blood vessels and nerves traverse. Meningiomas, the most common tumors in neurosurgical pathology, can arise at any location where the meninges are present, posing significant challenges. Meningiomas involving the jugular foramen and sublingual neural tube are particularly notable for their potential to extend from intracranial to extracranial sites, necessitating familiarity with extracranial anatomy, which is not typically encountered in clinical practice. A comprehensive understanding of anatomical characteristics, along with an ample field of view and working space, is crucial for handling the cerebellum, brainstem, and nerves meticulously. The use of surgical support tools such as neuromonitoring and navigation is essential for enhancing the safety of the procedure. Furthermore, preparedness for treatment options, rehabilitation, and adjunctive therapies is vital in the event of neurological symptoms such as those affecting the glossopharyngeal, vagal, or hypoglossal nerves.

Microsurgical resection of a samii type D jugular foramen schwannoma via the carotid triangle without removal of bony structure: how I do it.

BACKGROUND: Samii Type-D jugular foramen schwannomas (JFSs) are the most challenging for neurosurgeons because of anatomical complexity. Various neurosurgical approaches have been described to gain access to JF. METHODS: We present a female with incidental diagnosis of the Type-D JFS. Complete radical resection was achieved via the carotid triangle approach without any bony structure removal. And the patient was discharged asymptomatic and without new-developed neurological deficits. CONCLUSIONS: The carotid triangle is a secure and appropriate approach for some cases of selected Type-D JFSs. However, the specific indications of this approach should be further explored and investigated.

Surgical Management of Extradural Tumors at the Craniovertebral Junction - Insights from a Tertiary Care Center.

BACKGROUND: Craniovertebral junction (CVJ) tumors are challenging due to their unique anatomical location. This study aimed to evaluate the complexities in dealing with such precarious CVJ extradural lesions over the decade. METHODS: Twenty-seven patients of extradural CVJ tumors operated between 2009 and 2018 were included. The demographic details, neurological status, surgical approach, extent of resection, type of fixation, complications, and outcome at final follow-up were recorded for each patient. RESULTS: The mean age of the patients was 39.5 ± 20 years. Most (17/27) of the patients had involvement of a single level. Clivus was the most common (9/17) involved region followed by atlas (7/17) vertebrae. Majority of the patients (13/27) were operated through the posterior-only approach. About 15 patients (55.5%) had instability or extensive lesions that necessitated posterior fixation. None of the patients underwent anterior fixation. Gross and near total excision were achieved in 10 patients (37%) and 3 patients (11%) respectively while 14 patients underwent subtotal excision of tumor. On histopathological analysis, clival chordoma (8/27) was found to be the most common pathology followed by giant cell tumor (6/27), plasmacytoma (4/27), and multiple myeloma (2/27). Most patients (13 out of 27) had the same neurological status after the surgery. Six patients (22%) improved post-operatively with decreased weakness and spasticity. Thirteen (48%) patients underwent adjuvant radiotherapy. CONCLUSIONS: This retrospective study provides valuable insights into managing extradural CVJ tumors and highlights the importance of individualized approaches for optimal outcome.

[Transoral approach in surgery for chordomas extending into craniovertebral junction: a systematic review of the literature]. / Transoral'nyi dostup v khirurgii khordom, rasprostranyayushchikhsya v oblast' kraniovertebral'nogo perekhoda: sistematicheskii obzor literatury.

To date, treatment of chordomas involves maximal tumor resection followed by proton therapy. Various approaches are used depending on location of tumor (transcranial and through natural anatomical openings (nose, mouth), as well as their combinations). Although transoral approach has been introduced into neurosurgical practice for a long time, it is routinely used in patients with chordoma only in certain hospitals in the world. OBJECTIVE: To analyze postoperative outcomes in patients with chordomas of skull base and craniovertebral joint after transoral surgery. MATERIAL AND METHODS: We analyzed literature data devoted to patients with chordomas of skull base and craniovertebral joint after transoral surgery or another approach combined with transoral access. Among 111 primary articles, we selected 38 manuscripts including description of 109 patients with skull base chordoma who underwent transoral surgery or combination of approaches including transoral one. RESULTS: Gross total resection was achieved in 45.9% (n=50) of cases including 1 patient after en bloc resection. Subtotal resection was carried out in 28.4% of cases, partial - in 24.8%, biopsy - in 0.9% of cases. The complication rate in this group was 30%. The most common events were swelling of the tongue (10%) and diastasis of posterior pharyngeal wall sutures (8.2%) that required redo surgery. CSF leakage and meningitis were rare (1.8% and 3.6%, respectively). CONCLUSION: Transoral access allows for gross total resection of midline tumors with low incidence of severe complications. Combination of transoral and transcranial approaches is advisable to increase extent of resection.

Interdisciplinary Management of Skull Base Tumors. / Interdisziplinäre Behandlung von Schädelbasistumoren.

OBJECTIVE: Endoscopic endonasal skull base surgery has gained acceptance worldwide. Comparative analysis has demonstrated that endoscopic skull base surgery may have advantages for many pathologies of the anterior skull base, e. g., sinonasal malignant tumors; pathologies of the central skull base, e. g., pituitary adenomas, craniopharyngiomas; well-selected cases of planum sphenoidale and tuberculum sellae meningiomas; or for clival lesions, e. g., chordomas, chondrosarcomas, or selected meningiomas. Over the past three decades, interdisciplinary surgical teams, consisting of otolaryngologists and neurosurgeons, have provided detailed anatomical knowledge, suggested new approaches or modifications of established surgical techniques, and offered continued surgical education. METHOD: A review of pertinent literature was conducted with an emphasis on interdisciplinary endoscopic surgery of skull base lesions. RESULTS: Based on the authors̓ surgical experience in two different interdisciplinary endoscopic skull base centers, the authors classify approaches for endoscopic endonasal skull base surgery, describe indications, and key anatomic landmarks for common pathologies, and highlight surgical techniques to avoid complications. CONCLUSION: Interdisciplinary endonasal endoscopic surgery combines surgical expertise, improves resection rates for many pathologies, and minimizes morbidity by reducing the incidence of surgical complications.

Skull base surgery for malignant tumors: The 2nd international collaborative study (1995-2015).

BACKGROUND: The current study presents the effort of a global collaborative group to review the management and outcomes of malignant tumors of the skull base worldwide. PATIENTS AND METHODS: A total of 28 institutions contributed data on 3061 patients. Analysis evaluated clinical variables, survival outcomes, and multivariable factors associated with outcomes. RESULTS: The median age was 56 years (IQR 44-67). The open surgical approach was used in 55% (n = 1680) of cases, endoscopic resection was performed in 36% (n = 1087), and the combined approach in 9.6% (n = 294). With a median follow-up of 7.1 years, the 5-year OS DSS and RFS were 65%, 71.7% and 53%, respectively. On multivariable analysis, older age, comorbidities, histology, dural/intracranial involvement, positive margins, advanced stage, and primary site were independent prognostic factors for OS, DSS, and RFS. Adjuvant RT was a protective prognostic factor. CONCLUSION: The progress across various disciplines may have contributed to improved OS and DSS in this study compared to previous reports.