Endoscopic versus stereotactic procedure for pineal tumour biopsies: Comparative review of the literature and learning from a 25-year experience

Simultaneous Single-Trajectory Endoscopic Biopsy and Third Ventriculostomy in Pineal Region Tumors: A Systematic Review and Single Arm Meta-Analysis

OBJECTIVE

To assess the efficacy and surgical outcomes of the simultaneous single-trajectory endoscopic biopsy and third ventriculostomy (ETV) in pineal region tumors.

METHODS

A systematic review and meta-analysis adhering to Cochrane Standards and PRISMA framework were conducted. PubMed, Embase, and Web Of Science databases were searched until December 2023. Outcomes included rate of histopathologic diagnosis success, ETV success, complications, required VPS, and mortality.

RESULTS

Seventeen studies (N = 388) met inclusion criteria. Histopathologic diagnosis success rate was 90% for general population (95% CI: 86%-95%; I2 = 42%) and 94% for pediatric patients (95% CI: 89%-98%; I2 = 19%). ETV Success rate was 93% (95% CI: 88%-97%; I2 = 60%). An estimated risk of postoperative ETV complications was found to be 16% for the general population (95% CI: 5%-28%; I2 = 90%) and 5% for pediatric patients (95% CI: 0%-13%; I2 = 51%). The risk of requiring VPS was estimated as 2% (95% CI: 0%-4%; I2 = 39%) and for the pediatric population it was 7% (95% CI: 0%-16%; I2 = 69%). Mortality risk was found to be 1% (95% CI: 0%-3%; I2 = 0%).

CONCLUSIONS

Simultaneous endoscopic biopsy and ETV demonstrated high diagnostic and therapeutic success rates. The procedure's safety profile, with low mortality and complications, supports its role in treating hydrocephalus associated to pineal region tumors. Subgroup analyses revealed higher diagnostic success rates and required VPS in the pediatric population, whilst it had lower complication rates.

Machine learning-based classification of pineal germinoma from magnetic resonance imaging

Introduction

Surgical approaches for tissue diagnosis of pineal tumors have been associated with morbidity and mortality. The classification of images by machine learning (ML) may assist physicians in determining the extent of resection and treatment plans for a specific patient. Therefore, the present study aimed to evaluate the diagnostic performances of the ML-based models for distinguishing between pure and non-germinoma of the pineal area. In addition, the secondary objective was to compare diagnostic performances among feature extraction methods.

Methods

This is a retrospective cohort study of patients diagnosed with pineal tumors. We used the RGB feature extraction, histogram of oriented gradients (HOG), and local binary pattern methods from magnetic resonance imaging (MRI) scans; therefore, we trained an ML model from various algorithms to classify pineal germinoma. Diagnostic performances were calculated from a test dataset with several diagnostic indices.

Results

MRI scans from 38 patients with pineal tumors were collected and extracted features. As a result, the k-nearest neighbors (KNN) algorithm with HOG had the highest sensitivity of 0.81 (95% CI 0.78-0.84), while the random forest (RF) algorithm with HOG had the highest sensitivity of 0.82 (95% CI 0.79-0.85). Moreover, the KNN model with HOG had the highest AUC, at 0.845. Additionally, the AUCs of the artificial neural network and RF algorithms with HOG were 0.770 and 0.713, respectively.

Conclusions

The classification of images using ML is a viable way for developing a diagnostic tool to differentiate between germinoma and non-germinoma that will aid neurosurgeons in treatment planning in the future.

Neuroendoscopy in the management of pineal region tumours in children

INTRODUCTION

Pineal region tumours (PRTs) are more common in children and represent a wide variety of lesions. The practise of a radiation test dose is obsolete and a biochemical/histological diagnosis is recommended before further therapy. Many patients present with hydrocephalus. Advances in neuroendoscopic techniques have allowed safe and effective management of this obstructive hydrocephalus with an opportunity to sample cerebrospinal fluid (CSF) and obtain tissue for histopathology. Definitive surgery is required in less than a third. Endoscopic visualisation and assistance is increasingly used for radical resection, where indicated.

METHODOLOGY

Our experience of endoscopic surgery for paediatric PRTs from 2002 to 2021 is presented. All patients underwent MRI with contrast. Serum tumour markers were checked. If negative, endoscopic biopsy and endoscopic third ventriculostomy (ETV) were performed; and CSF collected for tumour markers and abnormal cells. For radical surgery, endoscope-assisted microsurgery procedures were performed to minimise retraction, visualise the extent of resection and confirm haemostasis.

RESULTS

M:F ratio was 2:1. The median age of presentation was 11 years. Raised ICP (88.88%) was the commonest mode of presentation. Nineteen patients had pineal tumours, one had a suprasellar and pineal tumour, one had disseminated disease, while six had tectal tumours. The ETB diagnosis rate was 95.45%, accuracy rate was 83.3% and ETV success rate was 86.96%.

CONCLUSION

Neuroendoscopy has revolutionised the management of paediatric PRTs. It is a safe and effective procedure with good diagnostic yield and allows successful concurrent CSF diversion, thereby avoiding major surgeries and shunt implantation. It is also helpful in radical resection of lesions, where indicated.

Benign and Malignant Tumors of the Pineal Region

Pineal region tumors fall into five broad categories: benign pineal region tumors, glial tumors, papillary tumors, pineal parenchymal tumors, and germ cell tumors. Genetic and transcriptional studies have identified key chromosomal alterations in germinomas (RUNDC3A, ASAH1, LPL) and in pineocytomas/pineoblastomas (DROSHA/DICER1, RB1). Pineal region tumors generally present with symptoms of hydrocephalus including nausea, vomiting, papilledema, and the classical Parinaud's triad of upgaze paralysis, convergence-retraction nystagmus, and light-near pupillary dissociation. Workup requires neuroimaging and tissue diagnosis via biopsy. In germinoma cases, diagnosis may be made based on serum or CSF studies for alpha-fetoprotein or beta-HCG making the preferred treatment radiosurgery, thereby preventing the need for unnecessary surgeries. Treatment generally involves three steps: CSF diversion in cases of hydrocephalus, biopsy through endoscopic or stereotactic methods, and open surgical resection. Multiple surgical approaches are possible for approach to the pineal region. The original approach to the pineal region was the interhemispheric transcallosal first described by Dandy. The most common approach is the supracerebellar infratentorial approach as it utilizes a natural anatomic corridor for access to the pineal region. The paramedian or lateral supracerebellar infratentorial approach is another improvement that uses a similar anatomic corridor but allows for preservation of midline bridging veins; this minimizes the chance for brainstem or cerebellar venous infarction. Determination of the optimal approach relies on tumor characteristics, namely location of deep venous structures to the tumor along with the lateral eccentricity of the tumor. The immediate post-operative period is important as hemorrhage or swelling can cause obstructive hydrocephalus and lead to rapid deterioration. Adjuvant therapy, whether chemotherapy or radiation, is based on tumor pathology. Improvements within pineal surgery will require improved technology for access to the pineal region along with targeted therapies that can effectively treat and prevent recurrence of malignant pineal region tumors.

Diagnosis and Treatment of Pineal Region Tumors in Adults: A EURACAN Overview

Simple Summary

Pineal region tumors are rare intracranial tumors. A deeper knowledge of these tumors’ molecular mechanisms has been gained in recent years, which has led to a new classification and new potential systemic treatments. Surgery remains the mainstay of treatment, while radiotherapy and systemic therapy depend on histological, molecular, and clinical characteristics. This paper highlights recent developments in the diagnosis and treatment of these tumors.

Abstract

Pineal region tumors are rare intracranial tumors, accounting for less than 1% of all adult intracranial tumor lesions. These lesions represent a histologically heterogeneous group of tumors. Among these tumors, pineal parenchymal tumors and germ cell tumors (GCT) represent the most frequent types of lesions. According to the new WHO 2021 classification, pineal parenchymal tumors include five distinct histotypes: pineocytoma (PC), pineal parenchymal tumors of intermediate differentiation (PPTID), papillary tumor of the pineal region (PTPR), pinealoblastoma (PB), and desmoplastic myxoid tumor of the pineal region, SMARCB1-mutant; GCTs include germinoma, embryonal carcinoma, yolk sac tumor, choriocarcinoma, teratoma, mixed GCTs. Neuroradiological assessment has a pivotal role in the diagnostic work-up, surgical planning, and follow-up of patients with pineal masses. Surgery can represent the mainstay of treatment, ranging from biopsy to gross total resection, yet pineal region tumors associated with obstructive hydrocephalus may be surgically managed via ventricular internal shunt or endoscopic third ventriculostomy. Radiotherapy remains an essential component of the multidisciplinary treatment approach for most pineal region tumors; however, treatment volumes depend on the histological subtypes, grading, extent of disease, and the combination with chemotherapy. For localized germinoma, the current standard of care is chemotherapy followed by reduced-dose whole ventricular irradiation plus a boost to the primary tumor. For pinealoblastoma patients, postoperative radiation has been associated with higher overall survival. For the other pineal tumors, the role of radiotherapy remains poorly studied and it is usually reserved for aggressive (grade 3) or recurrent tumors. The use of systemic treatments mainly depends on histology and prognostic factors such as residual disease and metastases. For pinealoblastoma patients, chemotherapy protocols are based on various alkylating or platinum-based agents, vincristine, etoposide, cyclophosphamide and are used in association with radiotherapy. About GCTs, their chemosensitivity is well known and is based on cisplatin or carboplatin and may include etoposide, cyclophosphamide, or ifosfamide prior to irradiation. Similar regimens containing platinum derivatives are also used for non-germinomatous GCTs with very encouraging results. However, due to a greater understanding of the biology of the disease’s various molecular subtypes, new agents based on targeted therapy are expected in the future. On behalf of the EURACAN domain 10 group, we reviewed the most important and recent developments in histopathological characteristics, neuro-radiological assessments, and treatments for pineal region tumors.

Evaluation of the Perioperative and Postoperative Course of Surgery for Pineal Germinoma in the SIOP CNS GCT 96 Trial

Background: CNS germinoma, being marker-negative, are mainly diagnosed by histological examination. These tumors predominantly appear in the suprasellar and/or pineal region. In contrast to the suprasellar region, where biopsy is the standard procedure in case of a suspected germ-cell tumor to avoid mutilation to the endocrine structures, pineal tumors are more accessible to primary resection. We evaluated the perioperative course of patients with pineal germinoma who were diagnosed by primary biopsy or resection in the SIOP CNS GCT 96 trial. Methods: Overall, 235 patients had germinoma, with pineal localization in 113. The relationship between initial symptoms, tumor size, and postoperative complications was analyzed. Results: Of 111 evaluable patients, initial symptoms were headache (n = 98), hydrocephalus (n = 93), double vision (n = 62), Parinaud syndrome (n = 57), and papilledema (n = 44). There was no significant relationship between tumor size and primary symptoms. A total of 57 patients underwent primary resection and 54 underwent biopsy. Postoperative complications were reported in 43.2% of patients after resection and in 11.4% after biopsy (p < 0.008). Biopsy was significantly more commonly performed on larger tumors (p= 0.002). Conclusions: These results support the practice of biopsy over resection for histological confirmation of pineal germinoma.

Radiotherapy After Endoscopic Biopsy in an Adult with Pineocytoma, the Rare Brain Tumor in an Adult: A Case Report and Literature Review

Tumors in the pineal region usually present with acute hydrocephalus. Histologic diagnosis is most important, as it greatly influences treatment, because over 17 tumor types occur in this area. Biopsies of these lesions play an important role in further management. Pineocytomas are benign and rare tumors that typically exhibit a slow progression. However, the appropriate treatment for pineocytoma varies. Surgical excision was considered for good long-term outcomes; however, this may not always be possible. Radiotherapy also appears to be effective in patients with residual pineocytomas. We report a case of pineocytoma with hemorrhagic transformation and complicated hydrocephalus. The patient refused to undergo aggressive tumor excision. Thus, the patient only underwent endoscopic biopsy and external ventricular drain (EVD) implantation, but the outcome was acceptable. In addition, we reviewed the current management strategies for pineocytomas in the literature.

A bi-foraminal craniometric-guided approach to endoscopic third ventriculostomy and biopsy of a pineal tumour

Background:

Pineal tumors are very rarely encountered, with an incidence of <1% of intracranial lesions in adults. Life-threatening hydrocephalus due to obstruction of the third ventricle can result from the location of these tumours. Endoscopic third ventriculostomy (ETV) and tumor biopsy is a safe and feasible strategy, particularly if the tumor appears benign. This mitigates the high risks of uncontrollable venous bleeding from open and stereotactic biopsies. While typically performed using either ipsilateral single or dual bur holes, the location of the tumor may require modifications to the standard endoscopic techniques.

Case Description:

A 55-year-old male presented with signs of intracranial hypertension and was found to have obstructive hydrocephalus due to a pineal tumour. The tumour displayed a right-sided dominance when the pre-operative imaging was assessed, which would risk forniceal injury if biopsied via a right-sided burr hole. Craniometric measurements revealed a superior trajectory to the tumour via the left foramen of Monro. A biforaminal approach was performed, with a traditional ETV using a right coronal bur hole and biopsy via a left frontal bur hole. This minimized forniceal stretching and allowed a safe biopsy.

Conclusion:

The bi-foraminal approach has not been widely described in the literature but can potentially avoid morbidity with biopsy in patients with right-sided pineal tumours. We believe this technique should be considered, particularly in low-resource settings where neuroendoscopy is not commonly done, and where the use of ipsilateral single or dual-bur holes may lead to forniceal injury.

Endoscopic versus stereotactic biopsies of intracranial lesions involving the ventricles

Stereotactic biopsies of ventricular lesions may be less safe and less accurate than biopsies of superficial lesions. Accordingly, endoscopic biopsies have been increasingly used for these lesions. Except for pineal tumors, the literature lacks clear, reliable comparisons of these two methods. All 1581 adults undergoing brain tumor biopsy from 2007 to 2018 were retrospectively assessed. We selected 119 patients with intraventricular or paraventricular lesions considered suitable for both stereotactic and endoscopic biopsies. A total of 85 stereotactic and 38 endoscopic biopsies were performed. Extra procedures, including endoscopic third ventriculostomy and tumor cyst aspiration, were performed simultaneously in 5 stereotactic and 35 endoscopic cases. In 9 cases (5 stereotactic, 4 endoscopic), the biopsies were nondiagnostic (samples were nondiagnostic or the results differed from those obtained from the resected lesions). Three people died: 2 (1 stereotactic, 1 endoscopic) from delayed intraventricular bleeding and 1 (stereotactic) from brain edema. No permanent morbidity occurred. In 6 cases (all stereotactic), additional surgery was required for hydrocephalus within the first month postbiopsy. Rates of nondiagnostic biopsies, serious complications, and additional operations were not significantly different between groups. Mortality was higher after biopsy of lesions involving the ventricles, compared with intracranial lesions in any location (2.4% vs 0.3%, p = 0.016). Rates of nondiagnostic biopsies and complications were similar after endoscopic or stereotactic biopsies. Ventricular area biopsies were associated with higher mortality than biopsies in any brain area.

Management of pineal region tumors in a pediatric case series

Pineal region tumors commonly present with non-communicating hydrocephalus. These heterogeneous histological entities require different therapeutic regimens. We evaluated our surgical experience concerning procurance of a histological diagnosis, management of hydrocephalus, and choice of antitumoral treatment. We analyzed the efficacy of neuroendoscopic biopsy and endoscopic third ventriculocisternostomy (ETV) in patients with pineal region tumors between 2006 and 2019 in a single-center retrospective cross-sectional study with regard to diagnostic yield, hydrocephalus treatment, as well as impact on further antitumoral management. Out of 28 identified patients, 23 patients presented with untreated hydrocephalus and 25 without histological diagnosis. One patient underwent open biopsy, and 24 received a neuroendoscopic biopsy with concomitant hydrocephalus treatment if necessary. Eighteen primary ETVs, 2 secondary ETVs, and 2 ventriculoperitoneal shunts (VPSs) were performed. Endoscopic biopsy had a diagnostic yield of 95.8% (23/24) and complication rates of 12.5% (transient) and 4.2% (permanent), respectively. ETV for hydrocephalus management was successful in 89.5% (17/19) with a median follow-up of more than 3 years. Following histological diagnosis, 8 patients (28.6%) underwent primary resection of their tumor. Another 9 patients underwent later-stage resection after either adjuvant treatment (n = 5) or for progressive disease during observation (n = 4). Eventually, 20 patients received adjuvant treatment and 7 were observed after primary management. One patient was lost to follow-up. Heterogeneity of pineal region tumor requires histological confirmation. Primary biopsy of pineal lesions should precede surgical resection since less than a third of patients needed primary surgical resection according to the German pediatric brain tumor protocols. Interdisciplinary decision making upfront any treatment is warranted in order to adequately guide treatment.

Complications of stereotactic biopsy of lesions in the sellar region, pineal gland, and brainstem: A retrospective, single-center study

Stereotactic biopsy (STB) is commonly used in the pathological diagnosis of intracranial lesions. The associated complication and mortality rates are low, but few reports with large sample sizes have assessed the complications of STB for lesions in the brain midline.To evaluate the complications of STB of lesions in the sellar region, pineal region, and brainstem.This was a retrospective analysis of patients who underwent STB of lesions in the sellar region, pineal region, and brainstem at the Neurosurgery Department, Sixth Medical Center, PLA General Hospital, China, between January 2015 and December 2017. The rates of and possible reasons for surgical complications (including bleeding) and mortality were analyzed.A total of 145 patients underwent STB of midline brain lesions, including 16 (11.0%) in the sellar region, 18 (12.4%) in the pineal region, and 111 (76.6%) in the brainstem. Successful biopsy of the sellar region, pineal region, and brainstem was achieved in 16/16 (100%), 18/18 (100%), and 107/111 (96.4%) patients, respectively. There were no complications following STB of lesion in the sellar or pineal regions. Complications occurred in 17/111 patients (15.3%) during/after brainstem biopsy, three of whom died (2.7%). The main clinical manifestations were facioplegia, facial pain, changes in blood pressure and heart rate, and difficulty breathing.STB of lesions in the sellar region, pineal region, and brainstem had a high success rate, but mortality was 2.7%. The occurrence of complications (15.3%) was closely related to the anatomical and functional characteristics of the region biopsied.

Tectal gliomas: assessment of malignant progression, clinical management, and quality of life in a supposedly benign neoplasm

OBJECTIVE Tectal gliomas constitute a rare and inhomogeneous group of lesions with an uncertain clinical course. Because these supposedly benign tumors are frequently followed up by observation over many years, the authors undertook this analysis of their own case series in an effort to demonstrate that the clinical course is highly variable and that there is a potential for a progressive biology. METHODS Clinical data analysis of 23 cases of tectal glioma (involving 9 children and 14 adults) was performed retrospectively. Radiographic data were analyzed longitudinally and MR images were evaluated for tumor volume, contrast enhancement, and growth progression. Quality of life was assessed using the EORTC BN20 and C30 questionnaires during follow-up in a subgroup of patients. RESULTS The patients' mean age at diagnosis was 29.2 years. The main presenting symptom at diagnosis was hydrocephalus (80%). Six patients were treated by primary tumor resection (26.1%), 3 patients underwent biopsy followed by resection (13.1%), and 3 patients underwent biopsy only (13.1%). For additional treatment of hydrocephalus, 14 patients (60.9%) received shunts and/or endoscopic third ventriculostomy. Radiographic tumor progression was observed in 47.9% of the 23 cases. The mean time between diagnosis and growth progression was 51.5 months, and the mean time to contrast enhancement was 69.7 months. Histopathological analysis was obtained in 12 cases (52.2%), resulting in 5 cases of high-grade glioma (3 cases of glioblastoma multiforme [GBM], grade IV, and 2 of anaplastic astrocytoma, grade III), 5 cases of pilocytic astrocytoma, 1 diffuse astrocytoma, and 1 ganglioglioma. Malignant progression was observed in 2 cases, with 1 case progressing from a diffuse astrocytoma (grade II) to a GBM (grade IV) within a period of 13 years. Quality-of-life measurements demonstrated distinct functional deficits compared to a healthy sample as well as glioma control cohorts. CONCLUSIONS Analysis of this case series shows that a major subpopulation of tectal gliomas show progression and malignant transformation in children as well as in adolescents. These tumors therefore cannot be considered inert lesions and require histological confirmation and close follow-up. Quality-of-life questionnaires show that tectal glioma patients might benefit from special psychological support in emotional, social, and cognitive functionality.

Ventriculostomy and endoscopic biopsy of pineal mass with hydrocephalus and unexpected definitive diagnosis

A 72-year-old female with no relevant medical history consulted in the emergency room for a two-week history of headache, vomiting and gait disturbance. Head CT scan revealed obstructive hydrocephalus secondary to a pineal mass with compression of the third ventricle. Magnetic Resonance showed another mass located in the right Lushcka foramen. Endoscopic third-ventriculostomy and biopsy of pineal mass were performed. Pathological analysis was consistent with metastasis of carcinoma. Full-body CT scan showed a lung mass related to primary carcinoma. The patient received systemic treatment for metastatic lung cancer. She died two months after diagnosis.

Clinical Management of Prostate Cancer Metastasis to Pineal Gland: Case Report and Review of Literature

BACKGROUND

Prostate cancer is the most common cancer among American men, with an incidence of approximately 233,000 cases per year. Intracranial metastases are rare and, specifically, metastasis to the pineal gland has only been reported in 2 postmortem cases in the literature.

CASE DESCRIPTION

We present the first documented case of confirmed prostate cancer metastasis to the pineal gland in a living patient. The patient underwent an endoscopic third ventriculostomy and pineal lesion biopsy with complete resolution of his hydrocephalus and presenting symptoms. His biopsy results confirmed the prostate origin of the metastasis, and he subsequently underwent stereotactic radiosurgery for treatment of this lesion.

CONCLUSIONS

This is the first report of the clinical management of metastatic prostate cancer to the pineal region and description of the clinical outcome. Although prostate cancer is the most common cancer in American men, metastasis to the pineal has only been reported twice from autopsy examinations. Overall, pineal tumors in the geriatric population are exceedingly rare and the age and comorbidities in this patient made management quite unique.

Neuroendoscopic Intraoperative Ultrasound-Guided Technique for Biopsy of Paraventricular Tumors

Different tumors can be encountered in the paraventricular regions, and whereas their deep location often make them difficult to access surgically, they may be amenable to chemotherapy and/or radiotherapy. Therefore, tumor biopsy and histologic diagnosis are mandatory to optimize treatment. Different technical procedures have been recommended; the neuroendoscopic approach is accepted and widely used, in particular with an enlarged ventricular system. However, specifically with paraventricular tumors, tissue sampling may be challenging. In such a scenario, the use of intraoperative ultrasonography technique can add some advantages regarding diagnostic accuracy and procedure safety. Accordingly, in this study we describe a novel technical procedure in 7 selected patients in whom tumor tissue biopsy was performed in a coupled neuroendoscopic and ultrasound-guided environment. We define a neuroendoscopic intraoperative ultrasound technique. The main advantages of this technique are the identification of the tumor that may not been clearly identified underneath the ventricular ependymal through the neuroendoscopic window alone, and furthermore, that this technique gives the possibility to detect the depth of the needle advance∖ment in the selected tissue while labeling the lesion beneath the ventricular ependyma. Moreover, intraoperative ultrasonography can reveal in a real-time fashion intracranial hemorrhages that may occur after tissue biopsy, therefore providing a useful tool to achieve valid and directed hemostasis when needed.

Outcome of single-trajectory rigid endoscopic third ventriculostomy and biopsy in the management algorithm of pineal region tumors: a case series and review of the literature

BACKGROUND

Tumors within the pineal region represent 1.5 to 8.5% of the pediatric brain tumors and 1.2% of all brain tumors. A management algorithm has been proposed in several publications. The algorithm includes endoscopic third ventriculostomy (ETV) and biopsy in cases presenting with hydrocephalus. In this series, we are presenting the efficacy of a single-trajectory approach for both ETV and biopsy.

METHODS

Eleven cases were admitted to Alexandria main university hospital from 2013 to 2016 presenting with pineal region tumors and hydrocephalus. Mean age at diagnosis was 11 years (1-27 years). All cases had ETV and biopsy using rigid ventriculoscope through a single trajectory from a burr hole planned on preoperative imaging. Follow-up period was 7-48 months.

RESULTS

All 11 cases presented with hydrocephalus and increased intracranial pressure manifestations. Histopathological diagnosis was successful in 9 out of 11 cases (81.8%). Three cases were germ-cell tumors, two cases were pineoblastomas, two cases were pilocytic astrocytomas, and two cases were grade 2 tectal gliomas. Five of the ETV cases (45.5%) failed and required VPS later on. Other complications of ETV included one case of intraventricular hemorrhage and a case with tumor disseminated to the basal cisterns.

CONCLUSION

In our series, we were able to achieve ETV and biopsy through a single trajectory and a rigid endoscope with results comparable to other studies in the literature.

MRI features of pediatric intracranial germ cell tumor subtypes

Intracranial germ cell tumors differ in histology and location, and require different clinical management strategies. We characterized the imaging features that may aid pre-operative differentiation of intracranial germinomas and non-germinomatous germ cell tumors (NGGCTs). This retrospective study analyzed 85 patients with intracranial germ cell tumors and adequate preoperative or pretreatment MRIs between 2000 and 2013 at our institution. Pretreatment MRI characteristics, apparent diffusion coefficient (ADC) values, tumor histopathology, and patient outcomes were compared. NGGCTs occurred in the pineal region and cerebral hemispheres more often than germinomas; all bifocal lesions were germinomas. NGGCTs (36.6 ± 17.0 mm) were significantly larger than germinomas (25.7 ± 11.6 mm; P = 0.002). The presence of pure solid tumor (45.5 vs. 20.0%, P = 0.033) and an infiltrative margin (20.0 vs. 3.3%, P = 0.035) were significantly more common in germinomas than NGGCTs. The presence of intratumoral T1 hyperintense foci (66.7 vs. 10.9%, P < 0.001) and moderate/marked enhancement (86.7 vs. 50.9%, P < 0.001) were significantly more common in NGGCTs than in germinomas. Mean ADC_mean values (×10^-3 mm²/s) were significantly lower in germinomas (1.113 ± 0.415) than in NGGCTs (2.011 ± 0.694, P = 0.001). Combined a lack of T1 hyperintense foci and an ADC_mean threshold value (1.143 × 10^-3 mm²/s) had the highest specificity (91.3%) and positive predictive value (92.3%), while the combination of lack of a T1 hyperintensense foci, no/mild enhancement, and an ADC_mean threshold value had 100% sensitivity and 100% negative-predictive value for discriminating germinomas from NGGCTs. Pre-operative conventional MRI characteristics and diffusion-weighted MRI help clinicians to assess patients with intracranial germ cell tumors. Tumor size, location, T1 hyperintense foci, intratumoral cystic components, tumor margin and enhancing patterns demonstrate contrast between germinomas and NGGCTs. Serum tumor markers and adjunctive combination with T1 hyperintensity and/or enhancing pattern with ADC offer potential in preoperative differentiating intracranial germinomas and NGGCTs.

A multiport MR-compatible neuroendoscope: spanning the gap between rigid and flexible scopes

OBJECTIVE Rigid endoscopes enable minimally invasive access to the ventricular system; however, the operative field is limited to the instrument tip, necessitating rotation of the entire instrument and causing consequent tissue compression while reaching around corners. Although flexible endoscopes offer tip steerability to address this limitation, they are more difficult to control and provide fewer and smaller working channels. A middle ground between these instruments-a rigid endoscope that possesses multiple instrument ports (for example, one at the tip and one on the side)-is proposed in this article, and a prototype device is evaluated in the context of a third ventricular colloid cyst resection combined with septostomy. METHODS A prototype neuroendoscope was designed and fabricated to include 2 optical ports, one located at the instrument tip and one located laterally. Each optical port includes its own complementary metal-oxide semiconductor (CMOS) chip camera, light-emitting diode (LED) illumination, and working channels. The tip port incorporates a clear silicone optical window that provides 2 additional features. First, for enhanced safety during tool insertion, instruments can be initially seen inside the window before they extend from the scope tip. Second, the compliant tip can be pressed against tissue to enable visualization even in a blood-filled field. These capabilities were tested in fresh porcine brains. The image quality of the multiport endoscope was evaluated using test targets positioned at clinically relevant distances from each imaging port, comparing it with those of clinical rigid and flexible neuroendoscopes. Human cadaver testing was used to demonstrate third ventricular colloid cyst phantom resection through the tip port and a septostomy performed through the lateral port. To extend its utility in the treatment of periventricular tumors using MR-guided laser therapy, the device was designed to be MR compatible. Its functionality and compatibility inside a 3-T clinical scanner were also tested in a brain from a freshly euthanized female pig. RESULTS Testing in porcine brains confirmed the multiport endoscope's ability to visualize tissue in a blood-filled field and to operate inside a 3-T MRI scanner. Cadaver testing confirmed the device's utility in operating through both of its ports and performing combined third ventricular colloid cyst resection and septostomy with an endoscope rotation of less than 5°. CONCLUSIONS The proposed design provides freedom in selecting both the number and orientation of imaging and instrument ports, which can be customized for each ventricular pathological entity. The lightweight, easily manipulated device can provide added steerability while reducing the potential for the serious brain distortion that happens with rigid endoscope navigation. This capability would be particularly valuable in treating hydrocephalus, both primary and secondary (due to tumors, cysts, and so forth). Magnetic resonance compatibility can aid in endoscope-assisted ventricular aqueductal plasty and stenting, the management of multiloculated complex hydrocephalus, and postinflammatory hydrocephalus in which scarring obscures the ventricular anatomy.

Endoscopic Histologic Mapping of a Mixed Germ Pineal Tumor

BACKGROUND

The accurate histologic diagnosis of germ cell tumors in the pineal region is a keystone for determining the best treatment strategy and prognosis. This situation poses a challenge for the neuropathologist, considering the lack of a standarized procedure to obtain biopsy samples, which results in few and small specimens, which are not suitable for diagnosis.

CASE DESCRIPTION

We report a case in which a pineal region mixed germ cell tumor was accurately diagnosed by performing histologic mapping through a dual burr-hole endoscopic approach. The technical pitfalls and other considerations necessary for obtaining an accurate diagnosis in this tumor subgroup are specified. In addition, the histologic analysis regarding the sampling technique used is described.

CONCLUSIONS

The supraorbital frontal endoscopic approach enables the surgeon to perform histologic mapping of pineal region tumors, allowing standarization of the procedure used to obtain the specimens. This approach could result in a more accurate diagnosis, especially in mixed germ cell neoplasms.

Endoscopic Versus Stereotactic Procedure for Pineal Tumor Biopsies: Focus on Overall Efficacy Rate

OBJECTIVE

The management of pineal region tumors depends on the histologic subtypes. Two minimally invasive techniques are available: endoscopic intraventricular biopsies and stereotactic biopsies. The recent Southampton and Lille series are the largest endoscopic and stereotactic series of pineal region tumors reporting both diagnosis rate and accuracy rate, respectively; we elaborated on these results in the light of other recent studies.

METHODS

We compared the Southampton endoscopic series with the Lille series, reflecting our 25-year experience of stereotactic biopsies, and the metadata of the literature for both approaches, as reported in the 2013 Report of the French-Speaking Society of Neurosurgery on tumors of the pineal region.

RESULTS

The results of the Southampton series match the endoscopic literature, in particular regarding the diagnosis rate (81.2%) and the perioperative morbidity (25.0%), and provide a rarely reported accuracy rate (78.6%), giving access to the overall efficacy rate (63.8%). The results of the Lille series match the stereotactic literature and show better results than endoscopic biopsies concerning the diagnosis rate (98.9%), accuracy rate (100%), resulting overall efficacy rate (98.9%), and perioperative morbidity (6.4%).

CONCLUSIONS

The Southampton and Lille series provide a unique opportunity to compare the overall efficacy rates of endoscopic and stereotactic biopsies, respectively. The stereotactic approach is safer and more effective for biopsies of pineal region tumors. To improve the safety and reliability of endoscopic biopsies, various methods have to be evaluated: alternative burr-hole strategies, use of neuronavigation, and a combination of flexible and rigid endoscopes.