Recurrent noncoding U1 snRNA mutations drive cryptic splicing in SHH medulloblastoma.

In cancer, recurrent somatic single-nucleotide variants-which are rare in most paediatric cancers-are confined largely to protein-coding genes1-3. Here we report highly recurrent hotspot mutations (r.3A>G) of U1 spliceosomal small nuclear RNAs (snRNAs) in about 50% of Sonic hedgehog (SHH) medulloblastomas. These mutations were not present across other subgroups of medulloblastoma, and we identified these hotspot mutations in U1 snRNA in only <0.1% of 2,442 cancers, across 36 other tumour types. The mutations occur in 97% of adults (subtype SHHδ) and 25% of adolescents (subtype SHHα) with SHH medulloblastoma, but are largely absent from SHH medulloblastoma in infants. The U1 snRNA mutations occur in the 5' splice-site binding region, and snRNA-mutant tumours have significantly disrupted RNA splicing and an excess of 5' cryptic splicing events. Alternative splicing mediated by mutant U1 snRNA inactivates tumour-suppressor genes (PTCH1) and activates oncogenes (GLI2 and CCND2), and represents a target for therapy. These U1 snRNA mutations provide an example of highly recurrent and tissue-specific mutations of a non-protein-coding gene in cancer.

Delayed inflammatory leukoencephalopathy after gastric bypass surgery.

We describe an unusual leukoencephalopathy in a female who developed global language and memory difficulties as well as diffuse FLAIR lesions in the cerebral white matter (WM) ~ 30 months after bariatric surgery. She had no detectable nutritional deficiency. She died suddenly due to cardiovascular disease. The cerebral WM revealed perivascular T-cell infiltrations and strong immunoreactivity for the amyloid precursor protein limited to axons, without signs of myelin or neuronal injury. Unexplained WM lesions have been reported in post-bariatric-surgery patients. Our findings suggest that altered immunity and axonal dysfunction could be responsible for leukoencephalopathy in some patients undergoing bariatric procedures.
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Amelanotic melanocytoma of the sella mimicking pituitary adenoma.

We describe a 50-year-old man with a well-demarcated intra- and extrasellar lesion and clinical signs of a non-functioning pituitary adenoma. Neuropathological examination revealed tumor composed of non-pigmented spindle cells arranged in tightly packed nests separated by delicate vascular septae. There was no significant cellular atypia or mitotic activity, and Ki67-positive nuclei were present in less than 1% of cells. The neoplastic cells were positive for S-100 and vimentin, and negative for numerous cellular markers including HMB45, anti-melanoma cocktail antibodies, and Masson melanin stain. Electron microscopy revealed scattered cells with small numbers of premelanosomes, aiding in the correct diagnosis of an amelanotic melanocytoma. This is the first case report of entirely amelanotic melanocytoma of meninges, and in a very unique location. BRAF was negative supporting the diagnosis of intracranial origin of the tumor. Approximately 2 years after subtotal resection and stereotactic radiosurgery the patient is alive and well with a non-progressive residual tumor.
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Mixed capillary-cavernous extramedullary intradural hemangioma of the spinal cord mimicking meningioma: Case report.

Hemangiomas are customarily described as low-grade vascular tumors most often located in the head and neck, but on rare occasions occurring in the intradural space of the spine. The different subtypes of hemangiomas can be distinguished histologically as capillary, cavernous, or mixed types. We describe a rare case of a mixed capillary-cavernous extramedullary intradural hemangioma of the thoracic spinal cord, mimicking meningioma radiologically.

Statin-associated Autoimmune Myopathies: A Pathophysiologic Spectrum.

BACKGROUND: Statins have recently been reported to cause a rare autoimmune inflammatory and/or necrotic myopathy that begins or persists after drug cessation. METHODS: We report on 26 patients seen at a neuromuscular centre between 2005 and 2011 who demonstrated muscle weakness/myalgias and creatine kinase elevations during or after statin treatment with continuation of signs and symptoms despite statin withdrawal. RESULTS: All patients were treated with immunosuppressive therapy with good response; all improved biochemically and 86% improved clinically. Sixty-five percent of patients who attempted to taper off immunosuppressive therapy relapsed. We report on a novel finding whereby five of the seven patients who underwent multiple biopsies throughout their disease demonstrated a transformation of their histological diagnosis, with four progressing from having myofibre necrosis with minimal or no inflammation to a diagnosis of polymyositis. CONCLUSIONS: This study offers preliminary evidence that statin-associated necrotizing myopathy and statin-associated polymyositis may not be separate entities but are part of the same pathophysiological spectrum. Both entities respond well to immunosuppression.

Inflammatory infratentorial progressive multifocal leukoencephalopathy in a patient with rheumatoid arthritis.

An 84-year-old man with rheumatoid arthritis (RA) treated with methotrexate, developed progressive confusion and cerebellar symptoms, and died approximately 2 months later. Neuropathological examination revealed progressive multifocal leukoencephalopathy (PML) involving the cerebellum and brainstem. The affected tissues displayed intense infiltrations by CD8+ T-cells and microglia. JC virus was localized in oligodendroglia and cerebellar granule cells. This case illustrates unusual localization of inflammatory PML in a patient with RA treated with methotrexate.

TERT promoter mutations are highly recurrent in SHH subgroup medulloblastoma.

Telomerase reverse transcriptase (TERT) promoter mutations were recently shown to drive telomerase activity in various cancer types, including medulloblastoma. However, the clinical and biological implications of TERT mutations in medulloblastoma have not been described. Hence, we sought to describe these mutations and their impact in a subgroup-specific manner. We analyzed the TERT promoter by direct sequencing and genotyping in 466 medulloblastomas. The mutational distributions were determined according to subgroup affiliation, demographics, and clinical, prognostic, and molecular features. Integrated genomics approaches were used to identify specific somatic copy number alterations in TERT promoter-mutated and wild-type tumors. Overall, TERT promoter mutations were identified in 21 % of medulloblastomas. Strikingly, the highest frequencies of TERT mutations were observed in SHH (83 %; 55/66) and WNT (31 %; 4/13) medulloblastomas derived from adult patients. Group 3 and Group 4 harbored this alteration in <5 % of cases and showed no association with increased patient age. The prognostic implications of these mutations were highly subgroup-specific. TERT mutations identified a subset with good and poor prognosis in SHH and Group 4 tumors, respectively. Monosomy 6 was mostly restricted to WNT tumors without TERT mutations. Hallmark SHH focal copy number aberrations and chromosome 10q deletion were mutually exclusive with TERT mutations within SHH tumors. TERT promoter mutations are the most common recurrent somatic point mutation in medulloblastoma, and are very highly enriched in adult SHH and WNT tumors. TERT mutations define a subset of SHH medulloblastoma with distinct demographics, cytogenetics, and outcomes.

Suction-modified Bergström muscle biopsy technique: experience with 13,500 procedures.

INTRODUCTION: Bergström needle muscle biopsies have been used by exercise physiologists for over 35 years but have been less accepted by neuromuscular clinicians due to size concerns. METHODS: We retrospectively reviewed over 13,500 muscle Bergström needle biopsies done over a 21-year period to determine sampling success, patient/subject experience, and complications. We compared sample yield between two different needles (Bergström vs. UCH), with and without suction modifications. RESULTS: Needle biopsies adequate for histology and enzymology were obtainable from the vastus lateralis, deltoid, biceps brachii, soleus, and medial gastrocnemius muscles, with a success rate of >99.9% and a minor complication rate of 0.15%. Approximately 450 muscle fibers were submitted for histologic assessment; suction modification and use of the Bergström vs. UCH needle were associated with larger sample size (P < 0.05). CONCLUSIONS: The suction-modified Bergström needle muscle biopsy technique is safe and provides an adequate sample size for histologic, ultrastructural, DNA, and enzyme analysis.

Nodular lesions of choroid plexus in Hurler disease.

Neuropathologic examination of six brains from children with Hurler disease revealed nodular lesions in the glomus of choroid plexus caused by proliferation of vacuolated pericytes, fibroblasts, and arachnoid cells on the background of collagenized and myxoid stroma. This localization of lesions can be explained by the presence of a rich vascular network, as well as cellular heterogeneity greater in the glomus than in other parts of the choroid plexus or in the brain parenchyma. The development of nodules did not correlate with the age, severity of hydrocephalus, or the degree of expansion of the perivascular spaces in the brain.

Pattern of Relapse and Treatment Response in WNT-Activated Medulloblastoma.

Over the past decade, wingless-activated (WNT) medulloblastoma has been identified as a candidate for therapy de-escalation based on excellent survival; however, a paucity of relapses has precluded additional analyses of markers of relapse. To address this gap in knowledge, an international cohort of 93 molecularly confirmed WNT MB was assembled, where 5-year progression-free survival is 0.84 (95%, 0.763-0.925) with 15 relapsed individuals identified. Maintenance chemotherapy is identified as a strong predictor of relapse, with individuals receiving high doses of cyclophosphamide or ifosphamide having only one very late molecularly confirmed relapse (p = 0.032). The anatomical location of recurrence is metastatic in 12 of 15 relapses, with 8 of 12 metastatic relapses in the lateral ventricles. Maintenance chemotherapy, specifically cumulative cyclophosphamide doses, is a significant predictor of relapse across WNT MB. Future efforts to de-escalate therapy need to carefully consider not only the radiation dose but also the chemotherapy regimen and the propensity for metastatic relapses.

Expression of survivin and p16(INK4a)/Cdk6/pRB proteins and induction of apoptosis in response to radiation and cisplatin in meningioma cells.

Although meningiomas represent the most common class of tumors of the central nervous system, the molecular events underlying their genesis and development are still not well defined, and therapeutic approaches based on the genetics of these tumors are currently lacking. In the present study we have used the immunoblotting technique to show that the p16(INK4A), Cdk6 and pRB proteins are differentially expressed in primary meningioma cells with 20-, 30- and 36-fold difference between the lowest and the highest levels of each protein, respectively. In addition, we present evidence that the level of the anti-apoptosis survivin protein is high in these benign tumors. Moreover, the annexin V-associated flow cytometry technique was used to show that 60% of meningioma cell cultures underwent apoptosis in response to both gamma-rays and cisplatin, and 50% of these cells exhibited significant sensitivity to hydroxyurea. These agents triggered apoptosis through the mitochondrial pathway, by increasing the Bax/Bcl-2 ratio. Interestingly, the induction of apoptosis following radiation and cisplatin was significant in all cells that expressed low levels of p16(INK4A), Cdk6 and pRB proteins. These data shed more light on the molecular biology of meningioma cells and suggest that survivin and proteins of the RB pathway could play a determinant role in the development and the treatment of meningiomas.

Macrophagic myofasciitis in children is a localized reaction to vaccination.

Macrophagic myofasciitis is a novel, "inflammatory myopathy" described after a variety of vaccinations, almost exclusively in adults. We examined the relevance of histological findings of this myopathy to the clinical presentation in pediatric patients. Muscle biopsies from 8 children (7 months to 6 years old) with histological features of macrophagic myofasciitis were reviewed and correlated with the clinical manifestations. Patients underwent quadriceps muscle biopsy for suspected mitochondrial disease (4 patients), spinal muscular atrophy (2 patients), myoglobinuria (1 patient), and hypotonia with motor delay (1 patient). All biopsies showed identical granulomas composed of periodic acid-Schiff-positive and CD68-positive macrophages. Characteristic aluminum hydroxide crystals were identified by electron microscopy in 2 cases. The biopsy established diagnoses other than macrophagic myofasciitis in 5 patients: spinal muscular atrophy (2), Duchenne muscular dystrophy (1), phospho-glycerate kinase deficiency (1), and cytochrome c oxidase deficiency (1). Three children with manifestations and/or a family history of mitochondrial disease had otherwise morphologically normal muscle. All children had routine vaccinations between 2 months and 1 year before the biopsy, with up to 11 intramuscular injections, including the biopsy sites. There was no correlation between histological findings of macrophagic myofasciitis in biopsies and the clinical symptoms. We believe that macrophagic myofasciitis represents a localized histological hallmark of previous immunization with the aluminum hydroxide adjuvants contained in vaccines, rather than a primary or distinct inflammatory muscle disease.

Primary angiosarcoma of the brain in a child.

We describe a pediatric case of primary angiosarcoma of the brain displaying striking intravascular papillary pattern, consistent with the "Dabska tumor," often in continuity with a massive, multifocal intravascular papillary endothelial hyperplasia. The tumor contained small hemangioma and obliterated dysplastic arteries as well as very large thin-walled veins. The surrounding brain tissue showed scattered telangiectasias, conglomerates of calcified dysplastic arteries, old hemorrhages and gliosis. Colocalization of these lesions suggests the development of a papillary angiosarcoma in the pre-existing vascular malformation. Although never reported, the possibility of a malignant transformation of endothelial papillary hyperplasia also should be considered in this case.

Tumor-to-Lesion Metastasis: Case Report of Carcinoma Metastasis to Multiple Sclerosis Lesion.

BACKGROUND: The term "tumor-to-lesion metastasis" is an extension of "tumor-to-tumor metastasis," which is a rare but well-documented phenomenon. Tumor metastasis to the meninges and/or central nervous system (CNS) is rare in patents with multiple sclerosis (MS), although MS lesions bear many similarities to the primary tumor microenvironment and metastatic niche. We present the first case of malignant tumor metastasis to MS lesions with immunophenotyping of inflammatory cells in the metastatic foci. CASE DESCRIPTION: A 45-year-old male patient with a 6-year history of MS and newly diagnosed lung carcinoma developed carcinoma metastases in the meninges and CNS, as well as into mixed active/inactive MS lesions. The carcinoma-hosting MS lesions exhibited abundant macrophages/microglia with ongoing demyelination but rare T cells. In comparison, a 46-year-old female patient with a 21-month history of MS and newly diagnosed gastric carcinoma was found to have leptomeningeal carcinomatosis and separate active MS lesions containing not only frequent macrophages/microglia but also T cells. CONCLUSIONS: The carcinoma-hosting MS lesions are unlike typical active lesions but recapitulate the CNS metastatic niche. Our observations suggest that metastasis-hosting MS lesions might require a distinct immune microenvironment to be permissive to the seeding and growth of metastatic tumors.

Opposing Effects of CREBBP Mutations Govern the Phenotype of Rubinstein-Taybi Syndrome and Adult SHH Medulloblastoma.

Recurrent mutations in chromatin modifiers are specifically prevalent in adolescent or adult patients with Sonic hedgehog-associated medulloblastoma (SHH MB). Here, we report that mutations in the acetyltransferase CREBBP have opposing effects during the development of the cerebellum, the primary site of origin of SHH MB. Our data reveal that loss of Crebbp in cerebellar granule neuron progenitors (GNPs) during embryonic development of mice compromises GNP development, in part by downregulation of brain-derived neurotrophic factor (Bdnf). Interestingly, concomitant cerebellar hypoplasia was also observed in patients with Rubinstein-Taybi syndrome, a congenital disorder caused by germline mutations of CREBBP. By contrast, loss of Crebbp in GNPs during postnatal development synergizes with oncogenic activation of SHH signaling to drive MB growth, thereby explaining the enrichment of somatic CREBBP mutations in SHH MB of adult patients. Together, our data provide insights into time-sensitive consequences of CREBBP mutations and corresponding associations with human diseases.

Muscle phosphofructokinase deficiency with neonatal seizures and nonprogressive course.

Muscle phosphofructokinase deficiency is known to cause childhood-onset exercise intolerance, muscle cramps, and myoglobinuria. Rarely, phosphofructokinase deficiency manifests in infancy as congenital myopathy and arthrogryposis with fatal outcome. Here, the authors report the case of a 2-year-old boy with infantile phosphofructokinase deficiency who presented on the third day of life with intractable seizures. Two of his sisters died in infancy with hypotonia, developmental delay, and seizure disorder of unclear etiology. On follow-up, he has had hypotonia and mild developmental delay. However, he continues to gain developmental milestones, and his seizures are now well controlled on carbamazepine. This presentation suggests expanding the phenotype of muscle phosphofructokinase deficiency to include early-onset neonatal seizures. It is also unusual in the relatively milder course of the infantile form of this disorder. The authors propose that this form of glycogen storage disease be considered in the differential diagnosis of neonatal seizures and early infantile nonprogressive muscle weakness.

Granular cell meningioma. A case report.

We describe a granular cell tumour developing in clear cell meningioma of the falx. Granular and clear cells showed immunoreactivity for vimentin, epithelial membrane antigen and progesterone receptors. This is the first case documenting arachnoid origin of neoplastic granular cells in meningioma.