Targeted BRAF and CTNNB1 next-generation sequencing allows proper classification of nonadenomatous lesions of the sellar region in samples with limiting amounts of lesional cells

Role of endoscopic endonasal approach for craniopharyngiomas extending into the third ventricle in adults

•EAA is an innovative, promising, safe and effective approach for 3VCPs.•Key of success is surgeon learning curve in endoscopy and patients selection.•With correct indications, EEA gives GTR and morbidity rate similar to other routes.•Clinical, tumoral and anatomical features should be considered for EEA selection.

Xanthogranuloma of the Sellar Region: A Comprehensive Review of Neuroimaging in a Rare Inflammatory Entity

Xanthogranuloma of the sellar region is a rare chronic inflammatory lesion resulting from secondary hemorrhage, inflammation, infarction, and necrosis of an existing Rathke’s cleft cyst, craniopharyngioma, or pituitary adenoma. Sellar xanthogranulomas are challenging to differentiate from other cystic lesions preoperatively due to the lack of characteristic imaging features. We performed a literature overview of the clinical and paraclinical features, treatment options, and long-term outcomes of patients with sellar xanthogranuloma, focusing on the preoperative radiological diagnosis. The hyperintense signal in both T1- and T2-weighted sequences, cystic or partially cystic morphology, ovoid shape, sellar epicenter, intra- and suprasellar location, intratumoral calcifications, linear rim contrast enhancement, and the absence of cavernous sinus invasion suggest xanthogranuloma in the preoperative differential diagnosis. An endoscopic endonasal gross total resection without radiotherapy is the preferred first-line treatment. Given the low rate of recurrence rate and low chance of endocrinological recovery, a mass reduction with decompression of the optic apparatus may represent an appropriate surgical goal. Identifying the xanthogranulomas’ mutational profile could complement histopathological diagnosis and give insight into their histo-pathogenesis. A better preoperative neuroimagistic diagnosis of sellar xanthogranulomas and differentiation from lesions with a poorer prognosis, such as craniopharyngioma, would result in an optimal personalized surgical approach.

Craniopharyngiomas

Craniopharyngiomas are rare epithelial tumours situated primarily in the sellar/parasellar region, occurring along the path of the craniopharyngeal duct. Whilst classed as histologically benign tumours, their unpredictable growth pattern and proximity to vital structures including the optic chiasm, hypothalamus, and pituitary gland renders them a considerable threat, with significant associated morbidity and increase in mortality. Occurring both in child and adulthood, their clinical manifestations are broad, commonly with symptoms/signs secondary to hypothalamic-pituitary dysfunction, raised intracranial pressure and visual compromise. They have two distinct histological subtypes (adamantinomatous and papillary), with unique patterns of age distribution, and genetic and molecular make-up. With increasing understanding of their genetic pathogenesis including BRAF V600E mutations in the papillary subtype, and β-catenin mutations in the adamantinomatous, further research provides hope for the discovery of targeted medical therapy that can exploit molecular changes occurring as a result of such alterations. Until then, primary treatment consists of surgery with or without radiotherapy, with intracystic aspiration, chemotherapy or irradiation being alternative options in selected patients. Long term management by an experienced multidisciplinary team is essential, given the breadth of complications, including hypothalamic morbidity, visual compromise, cognitive and neuropsychological sequelae and impairment to quality of life.

Immunohistochemistry or Molecular Analysis: Which Method Is Better for Subtyping Craniopharyngioma?

Craniopharyngioma (CP) is mainly classified into two pathological subtypes: adamantinomatous (ACP) and papillary (PCP). CTNNB1 (β-catenin) mutations are detected in ACPs, and the BRAF V600E mutation is detected in PCPs. However, genetic analysis is not always possible in general medical practice. In this study, we investigated whether immunohistochemistry could replace genetic analysis as an aid in subtype diagnosis. Here, 38 CP patients who had undergone their first tumor resection were included. Among the 38 cases, 22 were morphologically diagnosed as ACP, 10 cases were diagnosed as PCP, and six cases were diagnosed as undetermined CP that were morphologically difficult to classify as either ACP or PCP. Results of immunohistochemistry and genetic analysis and clinical features were compared. Based on the immunohistochemistry, 26 (22 ACPs and four undetermined CPs) showed nuclear β-catenin expression, 11 (nine PCPs and two undetermined CPs) exhibited positive BRAF V600E immunostaining, and one PCP showed membranous β-catenin expression and negative BRAF V600E immunostaining. Among the 26 nuclear β-catenin expression cases, 11 had CTNNB1 mutations; however, 15 cases had mutations of neither CTNNB1 nor BRAF V600E. All 11 BRAF V600E immunopositive cases had BRAF V600E mutations. When comparing clinical features, pediatric patients and those with tumor calcification and less solid components on MRI more commonly had nuclear β-catenin expression tumors than BRAF V600E immunopositive tumors, reflecting the differences in clinical features between ACP and PCP. Accordingly, immunohistochemistry can replace genetic analysis as an aid to determine the subtype diagnosis of CP in general medical practice.

Creative and Innovative Methods and Techniques for the Challenges in the Management of Adult Craniopharyngioma

Craniopharyngioma remains a major challenge in daily clinical practice. The pathobiology of the tumor is still elusive, and there are no consensus or treatment guidelines on the optimal management strategy for this relatively rare tumor. However, recent technical and scientific advances, including genomic and radiomic profiling, innovation in surgical approaches, more precise radiotherapy protocols, targeted therapy, and restoration of lost functions all have the potential to significantly improve the outcome of patients with craniopharyngioma in the near future. Although many of these innovative tools in the new armamentarium of the clinician are still in their infancy, they could reduce craniopharyngioma-related morbidity and mortality and improve the patients' quality of life. In this article, we discuss these creative and innovative approaches that may offer solutions to the obstacles faced in treating craniopharyngioma and future possibilities in improving the care of these patients.

The medical necessity of advanced molecular testing in the diagnosis and treatment of brain tumor patients

Accurate pathologic diagnoses and molecularly informed treatment decisions for a wide variety of cancers depend on robust clinical molecular testing that uses genomic, epigenomic, and transcriptomic-based tools. Nowhere is this more essential than in the workup of brain tumors, as emphasized by the incorporation of molecular criteria into the 2016 World Health Organization classification of central nervous system tumors and the updated official guidelines of the National Comprehensive Cancer Network. Despite the medical necessity of molecular testing in brain tumors, access to and utilization of molecular diagnostics is still highly variable across institutions, and a lack of reimbursement for such testing remains a significant obstacle. The objectives of this review are (i) to identify barriers to adoption of molecular testing in brain tumors, (ii) to describe the current molecular tools recommended for the clinical evaluation of brain tumors, and (iii) to summarize how molecular data are interpreted to guide clinical care, so as to improve understanding and justification for their coverage in the routine workup of adult and pediatric brain tumor cases.

Molecular Diagnostic of Solid Tumor Using a Next Generation Sequencing Custom-Designed Multi-Gene Panel

Next generation sequencing (NGS) allows parallel sequencing of multiple genes at a very high depth of coverage. The need to analyze a variety of targets for diagnostic/prognostic/predictive purposes requires multi-gene characterization. Multi-gene panels are becoming standard approaches for the molecular analysis of solid lesions. We report a custom-designed 128 multi-gene panel engineered to cover the relevant targets in 22 oncogene/oncosuppressor genes for the analysis of the solid tumors most frequently subjected to routine genotyping. A total of 1695 solid tumors were analyzed for panel validation. The analytical sensitivity is 5%. Analytical validation: (i) Accuracy: sequencing results obtained using the multi-gene panel are concordant using two different NGS platforms and single-gene approach sequencing (100% of 83 cases); (ii) Precision: consistent results are obtained in the samples analyzed twice with the same platform (100% of 20 cases). Clinical validation: the frequency of mutations identified in different tumor types is consistent with the published literature. This custom-designed multi-gene panel allows to analyze with high sensitivity and throughput 22 oncogenes/oncosuppressor genes involved in diagnostic/prognostic/predictive characterization of central nervous system tumors, non-small-cell lung carcinomas, colorectal carcinomas, thyroid nodules, pancreatic lesions, melanoma, oral squamous carcinomas and gastrointestinal stromal tumors.

Adamantinomatous Craniopharyngioma in an Adult: A Case Report with NGS Analysis

PURPOSE

Several recent studies have documented CTNNB1 and BRAF mutations which are mutually exclusive for adamantinomatous craniopharyngioma (ACP) and papillary craniopharyngioma (PCP) tumors. This discovery is helpful in the development of novel targeted therapies in successful clinical trials with BRAF mutations in PCP cases. However, no such targeted therapy is available yet for ACP. Here, we report novel mutations, which are not previously reported, in a case of an adult ACP using NGS analysis.

RESULTS

Patient DNA was sequenced using Ion PI v3 chip on Ion Proton. A total of 16 variants were identified in this tumor by NGS analysis, out of which four were missense mutations, seven were synonymous mutations, and five were intronic variants. In CTNNB1 gene a known missense mutation in c.101G>T; in TP53 a known missense mutation in c.215C>G; and two known missense variants in PIK3CA, viz., in c.1173A>G; in exon 7, and in c.3128T>C; in exon 21, were found, respectively. Seven synonymous mutations were detected in this tumor, viz., in IDH1 (rs11554137), in FGFR3 (rs7688609), in PDGFRA (rs1873778), in APC (COSM3760869), in EGFR (rs1050171), in MET (rs35775721), and in RET (rs1800861), respectively. Three known, intronic variants were found in genes, such as PIK3CA, KDR, and JAK3, respectively. Also, a 3'-UTR and a splice site acceptor site variant in CSF1R and FLT3 genes were found in this tumor. We have shown allele coverage, allele ratio, and p-value, for all these mutations. The p-values and Phred quality score were significantly high for these variants.

CONCLUSION

As reported in previous studies, in ACP tumors we found a CTNNB1 mutation by NGS analysis. The PIK3CA variants we detected were not known previously in ACP tumors. Finding the PIK3CA mutations in the ACP tumors may help develop targeted therapy for a subset of craniopharyngiomas with PIK3CA activating mutations. Clinical trials are in progress with specific PIK3CA inhibitors in advanced stages of many cancers.

Clinical and biological significance of adamantinomatous craniopharyngioma with CTNNB1 mutation

OBJECTIVE

The Wnt/β-catenin signaling pathway is strongly implicated in the pathogenesis of adamantinomatous craniopharyngioma (adaCP). However, there is no evidence that the CTNNB1 mutation activates the target gene of Wnt/β-catenin signaling, and it is unknown whether it affects the tumorigenesis of adaCP. To assess the effect of the CTNNB1 mutation of adaCP, the authors analyzed the correlation between the mutation and clinical, radiological, pathological, and biological findings.

METHODS

Between 2003 and 2015, 42 patients (24 male and 18 female, median age 42 years) with either papillary craniopharyngioma (papCP) or adaCP underwent tumor resection at the authors' institution. BRAF V600E and CTNNB1 in papCP and adaCP samples were sequenced by next-generation sequencing and the Sanger method, and mRNA expression levels of Axin2 and BMP4 were evaluated by RT-PCR. Axin2, BMP4, β-catenin, and BRAF expression were evaluated by immunohistochemistry. Other data were collected from clinical reports.

RESULTS

The BRAF V600E mutation was detected in all 10 cases of papCP (100%). CTNNB1 exon 3 mutations were detected in 21 of 31 (68%) cases of adaCP, excluding 1 case for which there were no available sequence data. The mRNA expression level of Axin2 was significantly higher in adaCPs with a CTNNB1 mutation than in those without (p < 0.05). The immunohistochemical findings of Axin2 and BMP4 did not correlate with CTNNB1 mutation positivity. When patients who received adjuvant radiation therapy were excluded, progression-free survival was shorter in the mutation-positive group than in the mutation-negative group (log-rank test, p = 0.031). Examination of clinical characteristics and immunohistochemical findings of adaCPs showed that there was no significant correlation between CTNNB1 mutation positivity and age, sex, tumor volume, gross-total resection, optic tract edema, calcification, or T1 signal intensity of cyst fluid on MRI, β-catenin, and MIB-1 index.

CONCLUSIONS

These results raise the possibility that the CTNNB1 mutation in adaCP may be associated with disease recurrence, and genes related to the Wnt/β-catenin signaling pathway might represent a therapeutic target.

Genetic and immune profiling for potential therapeutic targets in adult human craniopharyngioma

Craniopharyngioma is a rare tumor in adults. Although histologically benign, it can be locally aggressive and may require additional therapeutic modalities to surgical resection. Analyses including next generation sequencing, chromogenic and in situ hybridization, immunohistochemistry, and gene amplification were used to profile craniopharyngiomas (n=6) for frequently altered therapeutic targets. Four of six patients had the BRAF^V600E missense mutation, frequent in the papillary craniopharyngioma subtype. One patient had a missense mutation in the WNT pathway, specifically CTNNB1, often associated with the adamantinomatous subtype. Craniopharyngiomas lacked microsatellite instability, had low tumor mutational burden, but did express PD-L1 protein, indicating potential therapeutic value for immune checkpoint inhibition. We identified mutations not previously described, including an E318K missense mutation in the MITF gene, an R1407 frameshift in the SETD2 gene of the PIK3CA pathway, R462H in the NF2 gene, and a I463V mutation in TSC2. Two patients testing positive for EGFR expression were negative for the EGFRvIII variant. Herein, we identified several alterations such as those in BRAF^V600E and PD-L1, which may be considered as targets for combination therapy of residual craniopharygiomas.

Biomarkers in tumors of the central nervous system - a review

Until recently, diagnostics of brain tumors were almost solely based on morphology and immunohistochemical stainings for relatively unspecific lineage markers. Although certain molecular markers have been known for longer than a decade (combined loss of chromosome 1p and 19q in oligodendrogliomas), molecular biomarkers were not included in the WHO scheme until 2016. Now, the classification of diffuse gliomas rests on an integration of morphology and molecular results. Also, for many other central nervous system tumor entities, specific diagnostic, prognostic and predictive biomarkers have been detected and continue to emerge. Previously, we considered brain tumors with similar histology to represent a single disease entity. We now realize that histologically identical tumors might show alterations in different molecular pathways, and often represent separate diseases with different natural history and response to treatment. Hence, knowledge about specific biomarkers is of great importance for individualized treatment and follow-up. In this paper we review the biomarkers that we currently use in the diagnostic work-up of brain tumors.

Noninvasive molecular diagnosis of craniopharyngioma with MRI-based radiomics approach

Background

Frequent somatic mutations of BRAF and CTNNB1 were identified in both histological subtypes of craniopharyngioma (adamantinomatous and papillary) which shed light on target therapy to cure this oncogenic disease. The aim of this study was to investigate the noninvasive MRI-based radiomics diagnosis to detect BRAF and CTNNB1 mutations in craniopharyngioma patients.

Methods

Forty-four patients pathologically diagnosed as adamantinomatous craniopharyngioma (ACP) or papillary craniopharyngioma (PCP) were retrospectively studied. High-throughput features were extracted from manually segmented tumors in MR images of each case. The modifications-robustness in region of interests and Random Forest-based feature selection methods were adopted to select the most significant features. Random forest classifier with 10-fold cross-validation was applied to build our radiomics model.

Results

Four features were selected to make pathological diagnosis between ACP and PCP with area under the receiver operating characteristic curve (AUC) of 0.89, accurancy (ACC) of 0.86, sensitivity (SENS) of 0.89 and specificity (SPEC) of 0.85. The other two features were applied to estimate BRAF V600E mutation with AUC of 0.91, ACC of 0.93, SENS of 0.83 and SPEC of 0.97. Accurate predication of CTNNB1 mutation by three selected features was realized with AUC of 0.93, ACC of 0.86, SENS of 0.86 and SPEC of 0.86.

Conclusions

We developed a reliable MRI-based radiomics approach to perform pathological and molecular diagnosis in craniopharyngioma patients with considerably accurate prediction, which could offer potential guidance for clinical decision-making.

Electronic supplementary material

The online version of this article (10.1186/s12883-018-1216-z) contains supplementary material, which is available to authorized users.

Papillary craniopharyngioma in a 4-year-old girl with BRAF V600E mutation: a case report and review of the literature

INTRODUCTION

Craniopharyngiomas are one of the most frequently diagnosed hypothalamo-pituitary tumors in childhood. The adamantinomatous histological subtype accounts for most pediatric cases, while the papillary variant is almost exclusively diagnosed in adults. Here, we report a case of papillary craniopharyngioma in a very young child, confirmed by molecular tissue analysis.

CASE REPORT

A 4-year-old girl was being investigated for symptomatic central hypothyroidism. Brain MR imaging revealed a large solid/cystic suprasellar mass, splaying the optic chiasm and measuring 3 × 1.9 × 2.3 cm. The patient underwent a transsphenoidal near total resection of the lesion, which was encased within a tumor capsule. Post-operatively, the patient developed transient diabetes insipidus but otherwise recovered well. The pathology of the lesion was consistent with a papillary craniopharyngioma with regions of stratified squamous epithelium accompanied by superficial goblet cells and ciliated cells. Subsequent next-generation sequencing analysis of the lesion confirmed the presence of a BRAF V600E mutation (BRAFc.1799T>A p. (Val600Glu). To date, she remains free from progression 1 year following surgery.

CONCLUSION

This is the youngest case published to date of papillary craniopharyngioma with a confirmed BRAF V600E mutation. The case encourages discussion about the most appropriate adjuvant therapy for tumor progression in such cases, given the risks of radiotherapy to the developing brain and the increasing availability of oral BRAF inhibitor therapy.

BRAF V600E mutant papillary craniopharyngiomas: a single-institutional case series

PURPOSE

To describe the clinical, radiographic and surgical outcomes in a cohort of patients with BRAF V600E mutant papillary craniopharyngiomas.

METHODS

A retrospective review was performed to identify all patients with a histological diagnosis of CP operated upon at a single institution between 2005 and 2017. All cases with adequate material were sequenced to confirm the presence of BRAF V600E mutation.

RESULTS

Sixteen patients were included in the present study. Approach was endoscopic endonasal (EEA) in 14 and transcranial (TCA) in 2. All patients were adult with an average age of 50 years (24-88). Radiographic review demonstrated that the majority (93.7%) were suprasellar and twelve (75%) had third ventricular involvement. No tumor showed evidence of calcifications and 68.7% were mixed solid-cystic. All patients had some evidence of hypopituitarism and 62.5% had hypothalamic disturbances. GTR was achieved in 11/14 (78.6%) EEA and 0/2 (0%) TCA (p < 0.05). The mean length of stay was 17.5 days in the TCA group and 7.6 days in the EEA group (p < 0.05). There were no CSF leaks. Post-operatively, eleven (68.7%) developed new DI or new hypopituitarism. Nine increased their BMI with a mean increase of 12.3%, whereas six patients lost weight with a mean decrease of 5.3%.

CONCLUSIONS

BRAF V600E mutant papillary tumors represent a clearly distinct clinical-pathological entity of craniopharyngiomas. These are generally non-calcified suprasellar tumors that occur in adults. These distinct characteristics may someday lead to upfront chemotherapy. When surgery is necessary, EEA may be preferred over TCA.

A Clinical Rule for Preoperative Prediction of BRAF Mutation Status in Craniopharyngiomas

BACKGROUND

Papillary craniopharyngiomas are characterized by BRAFV600E mutations. Targeted therapy can elicit a dramatic radiographic regression of these tumors. Therefore, prediction of BRAF mutation status before definitive surgery could enable neoadjuvant treatment strategies.

OBJECTIVE

To establish preoperative prediction criteria to identify patients with a BRAF mutant craniopharyngioma.

METHODS

Sixty-four patients with craniopharyngioma were included in this study. We determined BRAF mutation status by targeted sequencing. After scoring interobserver variability between presurgical clinical data and radiographic features, we established a diagnostic rule for BRAF mutation in our discovery cohort. We then validated the rule in an independent cohort.

RESULTS

The BRAFV600E mutation was detected in 12 of 42 patients in the discovery cohort. There were no patients under age 18 with BRAF mutation. Calcification was rare in tumors with BRAF mutation (P < .001), and 92% of them were supradiaphragmatic in location. Combining these 3 features—older than 18 years, absence of calcification, and supradiaphragmatic tumor location—we established a rule for predicting BRAF mutation. In cases where all 3 criteria were fulfilled, the sensitivity and specificity for the presence of BRAF mutation were 83% and 93%, respectively. In the validation cohort (n = 22), the sensitivity was 100% and specificity was 89%.

CONCLUSION

We propose predictive criteria for a BRAF mutation in craniopharyngioma using preoperative clinical and radiographic data. This rule may be useful in identifying patients who could potentially benefit from neoadjuvant BRAFV600E-targeted systemic therapies.

Can tissue biomarkers reliably predict the biological behavior of craniopharyngiomas? A comprehensive overview

BACKGROUND

The growing interest in the molecular and genetic alterations of craniopharyngiomas (CPs) is embodied in recent studies revealing insights into the CP tumorigenesis and identifying novel molecular pathways amenable of targeted therapies. The actual impact of this new information, however, remains inconclusive.

METHODS

We present a comprehensive review of the accumulated knowledge on molecular biology of CPs and a critical analysis on the strengths and weaknesses of the studies focused on CP molecular/genetic alterations published to date.

RESULTS

A thorough analysis of the alterations of β-catenin/CTNNB1 and BRAF genes investigated in 1123 CP cases included in 27 studies, showed that, on average, CTNNB1 mutations were present in two-thirds of adamantinomatous CPs and BRAF mutations in 90% of papillary CPs. Their role as oncogenic drivers has not been well established. Although rare, coexistence of both mutations may occur. The involvement of pituitary stem cells in human CP tumorigenesis is still uncertain. Expression of stem markers in human CP samples predominantly occurred along the CP border in contact with brain tissue. Finally, none of the various molecular alterations which have been proposed as markers for CP recurrence can be used today as reliable predictors of the CP behavior.

CONCLUSIONS

The isolated evaluation of CPs' molecular or genetic profiles that do not take into consideration fundamental pathological and therapeutic factors, specifically the tumor topography and the degree of tumor removal, may actually generate confusion regarding the reliability of some biomarkers to predict the CP biological behavior.

Do craniopharyngioma molecular signatures correlate with clinical characteristics?

OBJECTIVE

Exome sequencing studies have recently demonstrated that papillary craniopharyngiomas (PCPs) and adamantinomatous craniopharyngiomas (ACPs) have distinct genetic origins, each primarily driven by mutually exclusive alterations: either BRAF (V600E), observed in 95% of PCPs, or CTNNB1, observed in 75%–96% of ACPs. How the presence of these molecular signatures, or their absence, correlates with clinical, radiographic, and outcome variables is unknown.

METHODS

The pathology records for patients who underwent surgery for craniopharyngiomas between May 2000 and March 2015 at Weill Cornell Medical College were reviewed. Craniopharyngiomas were identified and classified as PCP or ACP. Patients were placed into 1 of 3 groups based on their genomic mutations: BRAF mutation only, CTNNB1 mutation only, and tumors with neither of these mutations detected (not detected [ND]). Demographic, radiological, and clinical variables were collected, and their correlation with each genomic group was tested.

RESULTS

Histology correlated strongly with mutation group. All BRAF tumors with mutations were PCPs, and all CTNNB1 with mutations and ND tumors were ACPs. Preoperative and postoperative clinical symptoms and radiographic features did not correlate with any mutation group. There was a statistically significant relationship (p = 0.0323) between the age group (pediatric vs adult) and the mutation groups. The ND group tumors were more likely to involve the sella (p = 0.0065).

CONCLUSIONS

The mutation signature in craniopharyngioma is highly predictive of histology. The subgroup of tumors in which these 2 mutations are not detected is more likely to occur in children, be located in the sella, and be of ACP histology.

Rathke's Cleft Cyst as Origin of a Pediatric Papillary Craniopharyngioma

A 6-year old patient presented with an intra and suprasellar cystic lesion accompanied with impairment of the hypothalamic-pituitary axis and partial hypopituitarism. The most likely cause of sellar lesions in this age group are adamantinomatous craniopharyngioma (adaCP) or Rathke´s cleft cysts (RCCs). AdaCP are characterized by CTNNB1 mutations accompanied with aberrant nuclear beta-catenin expression. RCC show neither nuclear beta-catenin expression nor BRAF mutation. The latter is a hallmark of papillary craniopharyngiomas (papCP) that exhibit remarkable histological similarity with metaplasia of RCC. Diagnosis of the patient was elucidated by CTNNB1 and BRAF mutation screening, utilizing different approaches, as well as histological examination of markers, e.g., beta-catenin, claudin-1, EpCAM and the mutated BRAFV600E protein, which are known to be differentially expressed in sellar lesions. The case presented reveals extraordinary aspects for two reasons. Firstly, the lesion appeared clinically, on MRI, intraoperatively and histologically as RCC with prominent squamous metaplasia, but showing an expression pattern of markers also found in papCP, whilst exhibiting a hitherto undescribed BRAFV600E mutation. This important result documents a supposable transition of RCC metaplasia into a papillary craniopharyngioma (papCP). Secondly, this intriguing case shows unexpectedly that although papCP usually occurs almost exclusively in adults, it can also arise in childhood.

High-resolution melting and immunohistochemical analysis efficiently detects mutually exclusive genetic alterations of adamantinomatous and papillary craniopharyngiomas

Craniopharyngioma consists of adamantinomatous and papillary subtypes. Recent genetic analysis has demonstrated that the two subtypes are different, not only in clinicopathological features, but also in molecular oncogenesis. Papillary craniopharyngioma (pCP) is characterized by a BRAF mutation, the V600E (Val 600 Glu) mutation. Adamantinomatous craniopharyngioma (aCP) can be distinguished by frequent β-catenin gene (CTNNB1) mutations. Although these genetic alterations can be a diagnostic molecular marker, the precise frequency of these mutations in clinical specimens remains unknown. In this study, we first evaluated BRAF V600E and CTNNB1 mutations in four and 14 cases of pCP and aCP, respectively, using high-resolution melting analysis followed by Sanger sequencing. The results showed that 100% (4/4) of pCP cases had BRAF V600E mutations, while 78% (11/14) of the aCP cases had CTNNB1 mutations, with these genetic alterations being subtype-specific and mutually exclusive. Second, we evaluated BRAF V600E and CTNNB1 mutations by immunohistochemical analysis (IHC). All pCP cases showed positive cytoplasmic staining with the BRAF V600E-mutant antibody (VE-1), whereas 86% (12/14) of aCP cases showed positive cytoplasmic and nuclear staining for CTNNB1, suggesting a CTNNB1 mutation. Only one case of wild-type CTNNB1 on the DNA analysis showed immunopositivity on IHC. We did not detect a coexistence of BRAF V600E and CTNNB1 mutations in any single tumor, which indicated that these genetic alterations were mutually exclusive. We also report our modified IHC protocol for VE-1 staining, and present the possibility that BRAF V600E mutations can be used as a diagnostic marker of pCP in the differentiation of Rathke cleft cyst with squamous metaplasia.

Potential evolution of neurosurgical treatment paradigms for craniopharyngioma based on genomic and transcriptomic characteristics

The recent genomic and transcriptomic characterization of human craniopharyngiomas has provided important insights into the pathogenesis of these tumors and supports that these tumor types are distinct entities. Critically, the insights provided by these data offer the potential for the introduction of novel therapies and surgical treatment paradigms for these tumors, which are associated with high morbidity rates and morbid conditions. Mutations in the CTNNB1 gene are primary drivers of adamantinomatous craniopharyngioma (ACP) and lead to the accumulation of β-catenin protein in a subset of the nuclei within the neoplastic epithelium of these tumors. Dysregulation of epidermal growth factor receptor (EGFR) and of sonic hedgehog (SHH) signaling in ACP suggest that paracrine oncogenic mechanisms may underlie ACP growth and implicate these signaling pathways as potential targets for therapeutic intervention using directed therapies. Recent work shows that ACP cells have primary cilia, further supporting the potential importance of SHH signaling in the pathogenesis of these tumors. While further preclinical data are needed, directed therapies could defer, or replace, the need for radiation therapy and/or allow for less aggressive surgical interventions. Furthermore, the prospect for reliable control of cystic disease without the need for surgery now exists. Studies of papillary craniopharyngioma (PCP) are more clinically advanced than those for ACP. The vast majority of PCPs harbor the BRAF^v600e mutation. There are now 2 reports of patients with PCP that had dramatic therapeutic responses to targeted agents. Ongoing clinical and research studies promise to not only advance our understanding of these challenging tumors but to offer new approaches for patient management.

Postoperative outcome of body core temperature rhythm and sleep-wake cycle in third ventricle craniopharyngiomas

OBJECTIVE One of the more serious risks in the treatment of third ventricle craniopharyngiomas is represented by hypothalamic damage. Recently, many papers have reported the expansion of the indications for the endoscopic endonasal approach (EEA) to be used for these tumors as well. The aim of this study was to assess the outcome of sleep-wake cycle and body core temperature (BCT), both depending on hypothalamic control, in patients affected by craniopharyngiomas involving the third ventricle that were surgically treated via an EEA. METHODS All consecutive adult patients with craniopharyngiomas that were treated at one center via an EEA between 2014 and 2016 were prospectively included. Each patient underwent neuroradiological, endocrinological, and ophthalmological evaluation; 24-hour monitoring of the BCT rhythm; and the sleep-wake cycle before surgery and at follow-up of at least 6 months. RESULTS Ten patients were included in the study (male/female ratio 4:6, mean age 48.6 years, SD 15.9 years). Gross-total resection was achieved in 8 cases. Preoperative BCT rhythm was pathological in 6 patients. After surgery, these disturbances resolved in 2 cases, improved in another 3, and remained the same in 1 patient; also, 1 case of de novo onset was observed. Before surgery the sleep-wake cycle was pathological in 8 cases, and it was restored in 4 patients at follow-up. After surgery the number of patients reporting diurnal naps increased from 7 to 9. CONCLUSIONS The outcome of the sleep-wake cycle and BCT analyzed after EEA in this study is promising. Despite the short duration of the authors' experience, they consider these results encouraging; additional series are needed to confirm the preliminary findings.

Distinct patterns of primary and motile cilia in Rathke's cleft cysts and craniopharyngioma subtypes

Cilia are highly conserved organelles, which serve critical roles in development and physiology. Motile cilia are expressed in a limited range of tissues, where they principally regulate local extracellular fluid dynamics. In contrast, primary cilia are expressed by many vertebrate cell types during interphase, and are intimately involved in the cell cycle and signal transduction. Notably, primary cilia are essential for vertebrate hedgehog pathway activity. Improved detection of motile cilia may assist in the diagnosis of some pathologic entities such as Rathke's cleft cysts, whereas characterizing primary cilia in neoplastic tissues may implicate cilia-dependent signaling pathways as critical for tumorigenesis. We show that immunohistochemistry for the nuclear transcription factor FOXJ1, a master regulator of motile ciliogenesis, robustly labels the motile ciliated epithelium of Rathke's cleft cysts. FOXJ1 expression discriminates Rathke's cleft cysts from entities in the sellar/suprasellar region with overlapping histologic features such as craniopharyngiomas. Co-immunohistochemistry for FOXJ1 and markers that highlight motile cilia such as acetylated tubulin (TUBA4A) and the small GTPase ARL13B further enhance the ability to identify diagnostic epithelial cells. In addition to highlighting motile cilia, ARL13B immunohistochemistry also robustly highlights primary cilia in formalin-fixed paraffin-embedded sections. Primary cilia are present throughout the neoplastic epithelium of adamantinomatous craniopharyngioma, but are limited to basally oriented cells near the fibrovascular stroma in papillary craniopharyngioma. Consistent with this differing pattern of primary ciliation, adamantinomatous craniopharyngiomas express significantly higher levels of SHH, and downstream targets such as PTCH1 and GLI2, compared with papillary craniopharyngiomas. In conclusion, motile ciliated epithelium can be readily identified using immunohistochemistry for FOXJ1, TUBA4A, and ARL13B, facilitating the diagnosis of Rathke's cleft cysts. Primary cilia can be identified by ARL13B immunohistochemistry in routine pathology specimens. The widespread presence of primary cilia in adamantinomatous craniopharyngioma implicates cilia-dependent hedgehog signaling in the pathogenesis of adamantinomatous craniopharyngioma.

Suction Filter in Endoscopic Endonasal Surgery: A Technical Note

BACKGROUND

The collection of the greatest possible amount of pathologic tissue is of paramount importance in neurosurgery to achieve the most accurate histopathologic diagnosis, to perform all of the necessary biomolecular tests on the pathologic specimen, and to collect biological material for basic or translational science studies. This problem is particularly relevant in pituitary surgery because of the possible small size and soft consistency of tumors, which make them suitable for removal through suction, reducing the amount of available pathologic tissue. To solve this issue, we adopted a filter connected to the suction tube, which allows the surgeon to collect all of the tissue aspirated during surgery.

METHODS

Our experience of 1734 endoscopic endonasal procedures, performed adopting this device since 1998 to December 2015, has been revised to assess its advantages and limitations.

RESULTS

This system is easy-to-use, does not impair the surgical maneuvers, and does not add any relevant cost to the surgery. The tissue collected through the filter proved useful for diagnostic histologic and biomolecular analyses and for research purposes, without any relevant artifacts as a result of this method of collection.

CONCLUSIONS

The use of a filter has allowed us to obtain the greatest amount possible of pathologic tissue at each surgery. This surgical material has revealed to be helpful both for diagnostic and basic science purposes. The use of the filter has proven to be of particular importance for microadenomas, soft tumors, and supradiaphragmatic or skull base lesions with heterogeneous features, improving the accuracy of histopathologic diagnosis.