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

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

Cylindrical spirals and other concentric structures of skeletal muscle in patients with neurological diseases.

Cylindrical spirals (CSs) are ultrastructurally distinct, intracytoplasmic inclusions characterized by concentrically wrapped lamellae, which are rarely found in skeletal muscle biopsies on electron microscopy (EM). CSs are often confused with other EM concentric structures including concentric laminated bodies and mitochondrial concentric cristae (MCC), due to similarities in these ultrastructures. In this study, we found CSs in 9 muscle biopsies from 9 patients, accounting for 0.5% of the biopsies examined routinely by EM. The frequency of CSs in these muscles varied from sparse and segregated to focally frequent and aggregated. CS-associated features included muscle fiber denervation atrophy in all 9 cases, fiber type grouping in 7/8 cases, tubular aggregates in 3/9 cases, and MCC in 2/9 cases. We also compared the concentric structures and highlighted their differences to distinguish CSs from other similar structures. Clinically, 8 out of 9 patients were adults aged 41-74 years and only one patient was 17 month-old. CSs were associated with several neurological diseases including Huntington's disease, amyotrophic lateral sclerosis, Mitochondrial Encephalopathy, Lactic Acidosis, and Stroke-like episodes, and other complex neurological disorders with neuropathy/encephalopathy, as well as anti-MDA5+ dermatomyositis. Eight of nine patients had genetic findings such as trinucleotide repeat expansion of huntingtin gene, ALS2 variant, MT-TL1 m.3243A > G mutation, and PMP 22 gene deletion. These results suggest that CSs may be highly variable in frequency and likely are under-reported/under-detected; they may be associated with neurogenic myopathy or central/peripheral nervous system disorders including some genetic neurological/neuromuscular diseases. Our findings of more CS-associated neurological diseases and an association of CSs with muscle neurogenic features may contribute to a better understanding of the clinico-pathological significance of CSs.

An HLA-G/SPAG9/STAT3 axis promotes brain metastases.

Brain metastases (BM) are the most common brain neoplasm in adults. Current BM therapies still offer limited efficacy and reduced survival outcomes, emphasizing the need for a better understanding of the disease. Herein, we analyzed the transcriptional profile of brain metastasis initiating cells (BMICs) at two distinct stages of the brain metastatic cascade-the "premetastatic" or early stage when they first colonize the brain and the established macrometastatic stage. RNA sequencing was used to obtain the transcriptional profiles of premetastatic and macrometastatic (non-premetastatic) lung, breast, and melanoma BMICs. We identified that lung, breast, and melanoma premetastatic BMICs share a common transcriptomic signature that is distinct from their non-premetastatic counterparts. Importantly, we show that premetastatic BMICs exhibit increased expression of HLA-G, which we further demonstrate functions in an HLA-G/SPAG9/STAT3 axis to promote the establishment of brain metastatic lesions. Our findings suggest that unraveling the molecular landscape of premetastatic BMICs allows for the identification of clinically relevant targets that can possibly inform the development of preventive and/or more efficacious BM therapies.

Characterization of an RNA binding protein interactome reveals a context-specific post-transcriptional landscape of MYC-amplified medulloblastoma.

Pediatric medulloblastoma (MB) is the most common solid malignant brain neoplasm, with Group 3 (G3) MB representing the most aggressive subgroup. MYC amplification is an independent poor prognostic factor in G3 MB, however, therapeutic targeting of the MYC pathway remains limited and alternative therapies for G3 MB are urgently needed. Here we show that the RNA-binding protein, Musashi-1 (MSI1) is an essential mediator of G3 MB in both MYC-overexpressing mouse models and patient-derived xenografts. MSI1 inhibition abrogates tumor initiation and significantly prolongs survival in both models. We identify binding targets of MSI1 in normal neural and G3 MB stem cells and then cross referenced these data with unbiased large-scale screens at the transcriptomic, translatomic and proteomic levels to systematically dissect its functional role. Comparative integrative multi-omic analyses of these large datasets reveal cancer-selective MSI1-bound targets sharing multiple MYC associated pathways, providing a valuable resource for context-specific therapeutic targeting of G3 MB.

Evaluation of DNA Methylation Array for Glioma Tumor Profiling and Description of a Novel Epi-Signature to Distinguish IDH1/IDH2 Mutant and Wild-Type Tumors.

Molecular biomarkers, such as IDH1/IDH2 mutations and 1p19q co-deletion, are included in the histopathological and clinical criteria currently used to diagnose and classify gliomas. IDH1/IDH2 mutation is a common feature of gliomas and is associated with a glioma-CpG island methylator phenotype (CIMP). Aberrant genomic methylation patterns can also be used to extrapolate information about copy number variation in a tumor. This project's goal was to assess the feasibility of DNA methylation array for the simultaneous detection of glioma biomarkers as a more effective testing strategy compared to existing single analyte tests. METHODS: Whole-genome methylation array (WGMA) testing was performed using 48 glioma DNA samples to detect methylation aberrations and chromosomal gains and losses. The analyzed samples include 39 tumors in the discovery cohort and 9 tumors in the replication cohort. Methylation profiles for each sample were correlated with IDH1 p.R132G mutation, immunohistochemistry (IHC), and previous 1p19q clinical testing to assess the sensitivity and specificity of the WGMA assay for the detection of these variants. RESULTS: We developed a DNA methylation signature to specifically distinguish a IDH1/IDH2 mutant tumor from normal samples. This signature is composed of 11 CpG sites that were significantly hypermethylated in the IDH1/IDH2 mutant group. Copy number analysis using WGMA data was able to identify five of five positive samples for 1p19q co-deletion and was concordant for all negative samples. CONCLUSIONS: The DNA methylation signature presented here has the potential to refine the utility of WGMA to predict IDH1/IDH2 mutation status of gliomas, thus improving diagnostic yield and efficiency of laboratory testing compared to single analyte IDH1/IDH2 or 1p19q tests.

The proteomic landscape of glioblastoma recurrence reveals novel and targetable immunoregulatory drivers.

Glioblastoma (GBM) is characterized by extensive cellular and genetic heterogeneity. Its initial presentation as primary disease (pGBM) has been subject to exhaustive molecular and cellular profiling. By contrast, our understanding of how GBM evolves to evade the selective pressure of therapy is starkly limited. The proteomic landscape of recurrent GBM (rGBM), which is refractory to most treatments used for pGBM, are poorly known. We, therefore, quantified the transcriptome and proteome of 134 patient-derived pGBM and rGBM samples, including 40 matched pGBM-rGBM pairs. GBM subtypes transition from pGBM to rGBM towards a preferentially mesenchymal state at recurrence, consistent with the increasingly invasive nature of rGBM. We identified immune regulatory/suppressive genes as important drivers of rGBM and in particular 2-5-oligoadenylate synthase 2 (OAS2) as an essential gene in recurrent disease. Our data identify a new class of therapeutic targets that emerge from the adaptive response of pGBM to therapy, emerging specifically in recurrent disease and may provide new therapeutic opportunities absent at pGBM diagnosis.

A primary DICER1-sarcoma with KRAS and TP53 mutations in a child with suspected ECCL.

A child had been followed since infancy by our multi-disciplinary neuro-oncology clinic with annual magnetic resonance imaging (MRI) under the presumed diagnosis of encephalocraniocutaneous lipomatosis (ECCL), with clinical features including nevus psiloliparus, scalp lipoma, nodular skin tag on and coloboma of the eyelid, cortical atrophy and meningeal angiomatosis. At the age of 4, she was found to have a large temporoparietal lesion causing elevated intracranial pressure requiring surgical resection. Histopathological exam of the tumor was suggestive of an intracranial sarcoma. Sequencing analysis of the tumor revealed mutations in DICER1, KRAS and TP53. Subsequent germline testing confirmed DICER1 syndrome and revealed an insignificant FGFR1 variant at a low frequency. Methylation profile of the tumor showed the tumor clustered most closely with sarcoma (rhabdomyosarcoma-like), confirming this tumor to be a primary DICER1-sarcoma. Compared to the previously reported cases, our unique case of primary DICER1-sarcoma also demonstrated neurofilament and chromogranin positivity, and genomic instability with loss of chromosome 4p, 4q, 8p, 11p, and 19p, as well as gains in chromosome 7p, 9p, 9q, 13q, and 15q on copy variant analysis. The detailed sequencing and methylation information discovered in this unique case of DICER1-sarcoma will hopefully help further our understanding of this rare and emerging entity.

Spinal calcifying pseudoneoplasm of the neuraxis (CAPNON) and CAPNON-like lesions: CAPNON overlapping with calcified synovial cysts.

Calcifying pseudoneoplasm of the neuraxis (CAPNON) is a rare tumour-like fibro-osseous lesion in the neuraxis including the spine. It is diagnosed by the presence of the following histological features: granular amorphous to chondromyxoid fibrillary cores with calcification/ossification, peripheral palisading of spindle to epithelioid cells, variable fibrous stroma, and foreign body reaction with multinucleated giant cells, as well as positive NF-L immunostaining. Spinal CAPNON is sometimes named as tumoural calcinosis that is tumour-like dystrophic calcification usually in the periarticular tissue and also described in calcified synovial cyst (CSC). We examined clinical, radiological and pathological features of five spinal CAPNONs and 21 spinal CSCs including three recurrent lesions. The results demonstrated some radiological and pathological overlaps between these two entities, as well as distinct features of each entity to be diagnosed. All CAPNONs showed the diagnostic histological features with NF-L positivity mainly in lesion cores and variable CD8+ T-cells. In contrast, CSCs exhibited the synovial lining and variable degenerative/reactive changes with some CAPNON-like features, but mostly no to occasionally limited NF-L positivity and less CD8+ T-cells with statistically significant differences between groups of CAPNONs and CSCs. Four CSCs contained CAPNON-like foci with the CAPNON diagnostic features including prominent NF-L positivity, and some transitional features from CSC to CAPNON. As the pathogenesis of CAPNON is likely reactive/degenerative in association with an inflammatory/immunological process involving NF-L protein deposition, our findings suggest the link between spinal CAPNON and CSC, with possible transition from CSC to CAPNON or CAPNON developing in reaction to CSC.

ß-Catenin marks proliferating endothelial cells in glioblastoma.

BACKGROUND: Angiogenesis is a key process in the growth and maintenance of tumors. The Wnt signaling pathway is required for angiogenesis of the central nervous system though development of the blood-brain barrier and subsequent proliferation of endothelial cells during tumor growth. However, the specificity of the Wnt pathway in regulating endothelial cells of different central nervous systems remains to be investigated. MATERIALS & METHODS: Patient-derived tissue samples from 35 paraffin-embedded tumors were used to assess ß-catenin immunoexpression. Tumor samples consisted of the following pathologies: grade II diffuse astrocytoma, glioblastoma, hemangioblastoma, and metastatic adenocarcinoma (lung or breast primary). Average percent reactivity was recorded as a mean observed in ten high-power fields. The following scale was used to grade immunoreactivity: 0 = immunonegative, 1 = 1-25% reactive, 2 = 26-50% reactive, 3 = 51-75% reactive, 4 = 76-100% reactive. RESULTS: While we did not observe nuclear expression of ß-catenin in any samples, there was uniform cytoplasmic expression of ß-catenin within glial tumor cells. There was a clear distinction in tumor endothelial cells whereby diffuse staining was noted in areas of microvascular hyperplasia in GBM and a less immunoreactive profile in low-grade astrocytomas. By contrast, non-glial tumors, contained very minimal cytoplasmic ß-catenin expression in tumor and stromal cells and were devoid of immunoreactivity in endothelial cells. CONCLUSION: ß-catenin is unique marker of proliferating endothelial cells in GBM. Therapies targeting the spatial and structural heterogeneity inherent to GBM may prove to be efficacious and result in an improved survivorship.

De novo pathogenic variant in SETX causes a rapidly progressive neurodegenerative disorder of early childhood-onset with severe axonal polyneuropathy.

Pathogenic variants in SETX cause two distinct neurological diseases, a loss-of-function recessive disorder, ataxia with oculomotor apraxia type 2 (AOA2), and a dominant gain-of-function motor neuron disorder, amyotrophic lateral sclerosis type 4 (ALS4). We identified two unrelated patients with the same de novo c.23C > T (p.Thr8Met) variant in SETX presenting with an early-onset, severe polyneuropathy. As rare private gene variation is often difficult to link to genetic neurological disease by DNA sequence alone, we used transcriptional network analysis to functionally validate these patients with severe de novo SETX-related neurodegenerative disorder. Weighted gene co-expression network analysis (WGCNA) was used to identify disease-associated modules from two different ALS4 mouse models and compared to confirmed ALS4 patient data to derive an ALS4-specific transcriptional signature. WGCNA of whole blood RNA-sequencing data from a patient with the p.Thr8Met SETX variant was compared to ALS4 and control patients to determine if this signature could be used to identify affected patients. WGCNA identified overlapping disease-associated modules in ALS4 mouse model data and ALS4 patient data. Mouse ALS4 disease-associated modules were not associated with AOA2 disease modules, confirming distinct disease-specific signatures. The expression profile of a patient carrying the c.23C > T (p.Thr8Met) variant was significantly associated with the human and mouse ALS4 signature, confirming the relationship between this SETX variant and disease. The similar clinical presentations of the two unrelated patients with the same de novo p.Thr8Met variant and the functional data provide strong evidence that the p.Thr8Met variant is pathogenic. The distinct phenotype expands the clinical spectrum of SETX-related disorders.

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

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

Immunohistochemical Markers in the Diagnosis of Calcifying Pseudoneoplasm of the Neuraxis.

BACKGROUND: Calcifying pseudoneoplasm of the neuraxis (CAPNON) is a rare tumor-like lesion with unknown pathogenesis. It is likely under-reported due to diagnostic challenges including the nonspecific radiographic features, lack of diagnostic markers, and often asymptomatic nature of the lesions. METHODS: We performed detailed examination of 11 CAPNON specimens diagnosed by histopathology, with the help of electron microscopy and immunohistochemistry. RESULTS: Electron microscopy revealed the presence of fibrillary materials consistent with neurofilaments. In addition to some entrapped axons at the periphery of CAPNONs, we discovered that all specimens stained positive for neurofilament-light (NF-L) within the granular amorphous cores, but not neurofilament-phosphorylated (NF-p). CAPNONs also showed variable infiltration of CD8+ T-cells and a decreased ratio of CD4/CD8+ T-cells, suggesting an immune-mediated process in the pathogenesis of CAPNON. CONCLUSION: NF-L and CD4/CD8 immunostains may serve as diagnostic markers for CAPNON and shed light on its pathogenesis.

Wnt activation as a therapeutic strategy in medulloblastoma.

Medulloblastoma (MB) is defined by four molecular subgroups (Wnt, Shh, Group 3, Group 4) with Wnt MB having the most favorable prognosis. Since prior reports have illustrated the antitumorigenic role of Wnt activation in Shh MB, we aimed to assess the effects of activated canonical Wnt signaling in Group 3 and 4 MBs. By using primary patient-derived MB brain tumor-initiating cell (BTIC) lines, we characterize differences in the tumor-initiating capacity of Wnt, Group 3, and Group 4 MB. With single cell RNA-seq technology, we demonstrate the presence of rare Wnt-active cells in non-Wnt MBs, which functionally retain the impaired tumorigenic potential of Wnt MB. In treating MB xenografts with a Wnt agonist, we provide a rational therapeutic option in which the protective effects of Wnt-driven MBs may be augmented in Group 3 and 4 MB and thereby support emerging data for a context-dependent tumor suppressive role for Wnt/ß-catenin signaling.

Case report and literature review of Huntington disease with intermediate CAG expansion.

BACKGROUND: Huntington disease (HD) is a genetically inherited neurodegenerative disorder that classically involves a trinucleotide CAG repeat expansion on chromosome 4, with 36 repeats or greater being disease identifying. It generally presents between the age of 30 and 40 years old and is characterised by severe caudate/striatum degeneration with huntingtin protein aggregation. We present here the case of a patient in her early 80s who presented with 5-year history of worsening chorea and family history of HD but an intermediate length CAG expansion. METHODS: Genetic testing of CAG repeats on chromosome 4. Postmortem brain tissue was obtained and stained using immunohistochemistry for amyloid-beta, tau and glial fibrillary acidic protein (GFAP). Sections from the caudate/putamen were also analysed by p62 immunofluorescence. All sections were reviewed by trained neuropathologists. RESULTS: On genetic testing the patient was found to have a 28 CAG repeat on the longest expansion. Microscopic analysis revealed significant neuronal atrophy in the caudate and putamen with gliosis. Immunofluorescent staining demonstrated minimal intranuclear p62 inclusions suggesting little huntingtin aggregation present. Furthermore, there was significant amyloid-beta pathology (Thal-IV stage) and tau involvement in the medial temporal lobe (Braak stage II). CONCLUSION: This case provides clinical and pathological evidence to support an emerging clinical entity involving HD presentation in late age with an intermediate CAG repeat.

Hypertrophic Interstitial Neuropathy of the Trigeminal Nerve: Case Report and Literature Review.

BACKGROUND AND IMPORTANCE: Hypertrophic interstitial neuropathy (HIN) is an uncommon, non-neoplastic lesion typically affecting peripheral nerves. Cranial nerve (CN) involvement is exceedingly rare. We present a case of isolated trigeminal nerve HIN manifesting with V3 distribution neuralgia. CLINICAL PRESENTATION: A 50-yr-old male presented with left sided trigeminal neuralgia refractory to medical management. The patient underwent retromastoid craniectomy for possible microvascular decompression. Intra-operatively, the trigeminal nerve appeared to be focally enlarged with a sausage-like configuration. We selectively resected 1 fascicle which was predominantly involved. Histopathological examination revealed onion bulb formations composed of Schwann cells around centrally placed axons. A diagnosis of HIN was made. Postoperatively, the patient experienced complete resolution of symptoms. CONCLUSION: This is the third case of isolated trigeminal nerve HIN in the literature. We performed a selective resection in a patient presenting with trigeminal neuralgia, resulting in complete resolution of symptoms. It is reported here with intraoperative microscope images, along with a review and analysis of this topic as it related to CN.