PYROXD1-associated myopathy

PYROXD1-associated myopathy is a rare genetic form of limb-girdle muscular dystrophy (LGMD) with only 23 previous cases having been reported in the literature. The exact role of PYROXD1 in the pathophysiology of LGMD remains unclear. We describe two brothers who presented to the neuromuscular clinic with progressive weakness of their upper and lower limbs over the preceding decades. Our case highlights how recent advancements in genetic sequencing have revolutionised the diagnostic classification process for LGMD and provided opportunities to establish diagnoses for previously unclassified myopathies. We also illustrate how the increased adoption of muscle MRI to identify disease and target muscle biopsy can provide better quality and more informative samples for classification. Finally, our report details the clinical and histopathological findings found in both cases adding valuable data to the currently limited information published on PYROXD1-associated myopathy.

Pediatric nasal chondromesenchymal hamartomas: a case series

PURPOSE

Nasal chondromesenchymal hamartomas (NCMH) are rare, predominantly benign tumors of the sinonasal tract. The distinction from higher grade malignancy may be challenging based on imaging features alone. To increase the awareness of this entity among radiologists, we present a multi-institutional case series of pediatric NCMH patients showing the varied imaging presentation.

METHODS

Descriptive assessment of imaging appearances of the lesions on computed tomography (CT) and magnetic resonance imaging (MRI) was performed. In addition, we reviewed demographic information, clinical data, results of genetic testing, management, and follow-up data.

RESULTS

Our case series consisted of 10 patients, with a median age of 0.5 months. Intraorbital and intracranial extensions were both observed in two cases. Common CT findings included bony remodeling, calcifications, and bony erosions. MRI showed heterogeneous expansile lesion with predominantly hyperintense T2 signal and heterogenous post-contrast enhancement in the majority of cases. Most lesions exhibited increased diffusivity on diffusion weighted imaging and showed signal drop-out on susceptibility weighted images in the areas of calcifications. Genetic testing was conducted in 4 patients, revealing the presence of DICER1 pathogenic variant in three cases. Surgery was performed in all cases, with one recurrence in two cases and two recurrences in one case on follow-up.

CONCLUSION

NCMHs are predominantly benign tumors of the sinonasal tract, typically associated with DICER1 pathogenic variants and most commonly affecting pediatric population. They may mimic aggressive behavior on imaging; therefore, awareness of this pathology is important. MRI and CT have complementary roles in the diagnosis of this entity.

Primary orbital rhabdoid tumour masquerading as atypical persistent foetal vasculature

We present a case of primary rhabdoid tumour of the orbit. Presenting features at birth included congenital ptosis, conjunctival injection, hyphaema and microphthalmia. The unique presentation caused a late diagnosis following the development of rapid proptosis 6 months later. We suggest that orbital rhabdoid tumour be considered in the differential diagnoses of patients presenting with atypical persistent foetal vasculature features.

A Novel Variant in TPM3 Causing Muscle Weakness and Concomitant Hypercontractile Phenotype

A novel variant of unknown significance c.8A > G (p.Glu3Gly) in TPM3 was detected in two unrelated families. TPM3 encodes the transcript variant Tpm3.12 (NM_152263.4), the tropomyosin isoform specifically expressed in slow skeletal muscle fibers. The patients presented with slowly progressive muscle weakness associated with Achilles tendon contractures of early childhood onset. Histopathology revealed features consistent with a nemaline rod myopathy. Biochemical in vitro assays performed with reconstituted thin filaments revealed defects in the assembly of the thin filament and regulation of actin-myosin interactions. The substitution p.Glu3Gly increased polymerization of Tpm3.12, but did not significantly change its affinity to actin alone. Affinity of Tpm3.12 to actin in the presence of troponin ± Ca2+ was decreased by the mutation, which was due to reduced interactions with troponin. Altered molecular interactions affected Ca2+-dependent regulation of the thin filament interactions with myosin, resulting in increased Ca2+ sensitivity and decreased relaxation of the actin-activated myosin ATPase activity. The hypercontractile molecular phenotype probably explains the distal joint contractions observed in the patients, but additional research is needed to explain the relatively mild severity of the contractures. The slowly progressive muscle weakness is most likely caused by the lack of relaxation and prolonged contractions which cause muscle wasting. This work provides evidence for the pathogenicity of the TPM3 c.8A > G variant, which allows for its classification as (likely) pathogenic.

Anti-HMGCR myopathy: barriers to prompt recognition

Anti-HMGCR (3-hydroxy-3-methylglutaryl coenzyme A reductase) myopathy is an immune-mediated necrotising myopathy. Atypical presentations hinder its recognition and its prompt treatment. We present two patients with atypical clinical or pathological features. A 45-year-old woman had an asymptomatic serum creatine kinase (CK) of ~10 000 IU/L and muscle biopsy showing minimal changes. She then developed slowly progressive proximal weakness, diagnosed as limb-girdle muscular dystrophy but with negative genetics. Twelve years later, now with severe proximal weakness, her MR scan of muscle showed diffuse asymmetrical fatty degeneration, with conspicuous hyperintense STIR signal abnormalities. HMGCR antibodies were positive and she partially improved with immunosuppression. The second patient developed slowly progressive proximal limb weakness with a high serum CK (~4000 IU/L); muscle biopsy showed a lymphocyte infiltrate with angiocentric distribution suggesting vasculitis. Serum HMGCR antibodies were positive. Anti-HMGCR myopathy can present as a slowly progressive myopathy with atypical pathology. HMGCR antibody screening is indicated for people with suspected limb-girdle muscular dystrophy or atypical inflammatory muscle conditions.

Congenital orbital teratoma: A case report with foetal presentation

Congenital orbital teratomas are rare entities with few case reports detailing their prenatal and perinatal imaging features. We present the case of a congenital orbital teratoma initially detected as cystic lesion on prenatal ultrasound, with foetal and postnatal imaging showing evolution of characteristic MRI appearances. Knowledge of these appearances and the ability to diagnose these rare entities in foetal life can aid management and operative planning in the immediate postnatal period.

Germline homozygous missense DEPDC5 variants cause severe refractory early-onset epilepsy, macrocephaly and bilateral polymicrogyria

DEPDC5 (DEP Domain-Containing Protein 5) encodes an inhibitory component of the mammalian target of rapamycin (mTOR) pathway and is commonly implicated in sporadic and familial focal epilepsies, both non-lesional and in association with focal cortical dysplasia. Germline pathogenic variants are typically heterozygous and inactivating. We describe a novel phenotype caused by germline biallelic missense variants in DEPDC5. Cases were identified clinically. Available records, including magnetic resonance imaging and electroencephalography, were reviewed. Genetic testing was performed by whole exome and whole-genome sequencing and cascade screening. In addition, immunohistochemistry was performed on skin biopsy. The phenotype was identified in nine children, eight of which are described in detail herein. Six of the children were of Irish Traveller, two of Tunisian and one of Lebanese origin. The Irish Traveller children shared the same DEPDC5 germline homozygous missense variant (p.Thr337Arg), whereas the Lebanese and Tunisian children shared a different germline homozygous variant (p.Arg806Cys). Consistent phenotypic features included extensive bilateral polymicrogyria, congenital macrocephaly and early-onset refractory epilepsy, in keeping with other mTOR-opathies. Eye and cardiac involvement and severe neutropenia were also observed in one or more patients. Five of the children died in infancy or childhood; the other four are currently aged between 5 months and 6 years. Skin biopsy immunohistochemistry was supportive of hyperactivation of the mTOR pathway. The clinical, histopathological and genetic evidence supports a causal role for the homozygous DEPDC5 variants, expanding our understanding of the biology of this gene.

Andersen-Tawil syndrome: deep phenotyping reveals significant cardiac and neuromuscular morbidity

Andersen-Tawil syndrome is a neurological channelopathy caused by mutations in the KCNJ2 gene that encodes the ubiquitously expressed Kir2.1 potassium channel. The syndrome is characterized by episodic weakness, cardiac arrythmias and dysmorphic features. However, the full extent of the multisystem phenotype is not well described. In-depth, multisystem phenotyping is required to inform diagnosis and guide management. We report our findings following deep multimodal phenotyping across all systems in a large case series of 69 total patients, with comprehensive data for 52. As a national referral centre, we assessed point prevalence and showed it is higher than previously reported, at 0.105 per 100 000 population in England. While the classical phenotype of episodic weakness is recognized, we found that a quarter of our cohort have fixed myopathy and 13.5% required a wheelchair or gait aid. We identified frequent fat accumulation on MRI and tubular aggregates on muscle biopsy, emphasizing the active myopathic process underpinning the potential for severe neuromuscular disability. Long exercise testing was not reliable in predicting neuromuscular symptoms. A normal long exercise test was seen in five patients, of whom four had episodic weakness. Sixty-seven per cent of patients treated with acetazolamide reported a good neuromuscular response. Thirteen per cent of the cohort required cardiac defibrillator or pacemaker insertion. An additional 23% reported syncope. Baseline electrocardiograms were not helpful in stratifying cardiac risk, but Holter monitoring was. A subset of patients had no cardiac symptoms, but had abnormal Holter monitor recordings which prompted medication treatment. We describe the utility of loop recorders to guide management in two such asymptomatic patients. Micrognathia was the most commonly reported skeletal feature; however, 8% of patients did not have dysmorphic features and one-third of patients had only mild dysmorphic features. We describe novel phenotypic features including abnormal echocardiogram in nine patients, prominent pain, fatigue and fasciculations. Five patients exhibited executive dysfunction and slowed processing which may be linked to central expression of KCNJ2. We report eight new KCNJ2 variants with in vitro functional data. Our series illustrates that Andersen-Tawil syndrome is not benign. We report marked neuromuscular morbidity and cardiac risk with multisystem involvement. Our key recommendations include proactive genetic screening of all family members of a proband. This is required, given the risk of cardiac arrhythmias among asymptomatic individuals, and a significant subset of Andersen-Tawil syndrome patients have no (or few) dysmorphic features or negative long exercise test. We discuss recommendations for increased cardiac surveillance and neuropsychometry testing.

Muscle biopsy in myositis: What the rheumatologist needs to know

The appropriate analysis of skeletal muscle tissues is a key element in many diagnostic procedures and can deliver valuable information about the organ that is affected. Although arguably the frequency of muscle biopsy may be declining in certain domains where genetic analysis is now the first line of diagnostic evaluation, it still has an important role in assessment of patients with neuromuscular disorders such as congenital myopathies, muscular dystrophies, metabolic and inflammatory diseases. Here, we have comprehensively discussed the aspects of a modern and fruitful approach to muscle biopsy histopathological studies in rheumatological disorders. We have focussed on the neuromuscular involvement in myositis and its differential diagnoses in both adult and paediatric settings. We have also covered the clinical indications for the biopsy, technical aspects and practical points relevant for the rheumatologists. Finally, we have critically discussed the current and future opportunities that a muscle biopsy may offer and its limitations.

HGG-32. Durable response to mTOR inhibitor after failing Checkpoint inhibitors in Ultra-Hypermutated High grade glioma in context of CMMRD

BACKGROUND: Paediatric High Grade Gliomas (HGG) have poor outcomes with conventional treatment. HGG in association with constitutional DNA mismatch repair deficiency (CMMRD) are hypermutated and have shown dramatic response to checkpoint inhibitors. Salvage following progression or failure to respond to check point inhibitors has rarely been reported. We describe a successful alternative therapeutic approach targeting the activated pathway (mTOR) in a hypermutated HGG. CASE SUMMARY: A 6-year-old girl presenting with seizures was diagnosed with left frontal lobe HGG with concurrent neck mass (Pilomatrixoma). Presence of synchronous tumours raised the possibility of cancer predisposition; the HGG was hypermutated with germline PMS2 mutation confirming diagnosis of CMMRD. Near total resection was undertaken followed by focal radiotherapy 54 Gy, with 1 cycle of concomitant CCNU. MRI post radiotherapy showed tumour progression. Anti-PDl inhibitor Nivolumab was commenced. CTLA-4 antibody, Ipilimumab was added after 4 cycles of Nivolumab due to poor response. Tumour response was seen, but dual therapy had to be discontinued due to toxicity. The tumour progressed following further single agent Nivolumab. In view of multiple mutations in the mTOR pathway (NF1, PIK3/PTEN, TSC1, TSC2), a mTOR inhibitor, Everolimus was commenced. There was 25% tumour reduction after 4 weeks treatment and further reduction after 6 months. Resection of residual tumour showed necrotic tissue only. There continues to be a sustained response to Everolimus for over 12 months. DISCUSSION: Approximately a third of CMMRD HGG respond to checkpoint inhibitors. For those that don’t, these hypermutated tumours offers the possibility of targeting specific molecular pathways. Response to Everolimus in HGG harbouring mTOR aberrations have been described. To our knowledge this is the first report of successful use of mTOR inhibitor in CMMRD HGG. CONCLUSION: Targeted molecular treatment for patients with CMMRD hypermutated brain tumours should be considered according to the mutated pathways.

Repurposing Vandetanib plus Everolimus for the Treatment of ACVR1-Mutant Diffuse Intrinsic Pontine Glioma

Somatic mutations in ACVR1 are found in a quarter of children with diffuse intrinsic pontine glioma (DIPG), but there are no ACVR1 inhibitors licensed for the disease. Using an artificial intelligence-based platform to search for approved compounds for ACVR1-mutant DIPG, the combination of vandetanib and everolimus was identified as a possible therapeutic approach. Vandetanib, an inhibitor of VEGFR/RET/EGFR, was found to target ACVR1 (K d = 150 nmol/L) and reduce DIPG cell viability in vitro but has limited ability to cross the blood-brain barrier. In addition to mTOR, everolimus inhibited ABCG2 (BCRP) and ABCB1 (P-gp) transporters and was synergistic in DIPG cells when combined with vandetanib in vitro. This combination was well tolerated in vivo and significantly extended survival and reduced tumor burden in an orthotopic ACVR1-mutant patient-derived DIPG xenograft model. Four patients with ACVR1-mutant DIPG were treated with vandetanib plus an mTOR inhibitor, informing the dosing and toxicity profile of this combination for future clinical studies. SIGNIFICANCE: Twenty-five percent of patients with the incurable brainstem tumor DIPG harbor somatic activating mutations in ACVR1, but there are no approved drugs targeting the receptor. Using artificial intelligence, we identify and validate, both experimentally and clinically, the novel combination of vandetanib and everolimus in these children based on both signaling and pharmacokinetic synergies.This article is highlighted in the In This Issue feature, p. 275.

Bi-allelic loss-of-function OBSCN variants predispose individuals to severe recurrent rhabdomyolysis

Rhabdomyolysis is the acute breakdown of skeletal myofibres in response to an initiating factor, most commonly toxins and over exertion. A variety of genetic disorders predispose to rhabdomyolysis through different pathogenic mechanisms, particularly in patients with recurrent episodes. However, most cases remain without a genetic diagnosis. Here we present six patients who presented with severe and recurrent rhabdomyolysis, usually with onset in the teenage years; other features included a history of myalgia and muscle cramps. We identified ten bi-allelic loss-of-function variants in the gene encoding obscurin (OBSCN) predisposing individuals to recurrent rhabdomyolysis. We show reduced expression of OBSCN and loss of obscurin protein in patient muscle. Obscurin is proposed to be involved in SR function and Ca2+ handling. Patient cultured myoblasts appear more susceptible to starvation as evidenced by a greater decreased in SR Ca2+ content compared to control myoblasts. This likely reflects a lower efficiency when pumping Ca2+ back into the SR and/or a decrease in Ca2+ SR storage ability when metabolism is diminished. OSBCN variants have previously been associated with cardiomyopathies. None of the patients presented with a cardiomyopathy and cardiac examinations were normal in all cases in which cardiac function was assessed. There was also no history of cardiomyopathy in first degree relatives, in particular in any of the carrier parents. This cohort is relatively young, thus follow-up studies and the identification of additional cases with bi-allelic null OBSCN variants will further delineate OBSCN-related disease and the clinical course of disease.

MRI Patterns in Pediatric CNS Hemophagocytic Lymphohistiocytosis

BACKGROUND AND PURPOSE

Neuroimaging has an important role in detecting CNS involvement in children with systemic or CNS isolated hemophagocytic lymphohistiocytosis. We characterized a cohort of pediatric patients with CNS hemophagocytic lymphohistiocytosis focusing on neuroradiologic features and assessed whether distinct MR imaging patterns and genotype correlations can be recognized.

MATERIALS AND METHODS

We retrospectively enrolled consecutive pediatric patients diagnosed with hemophagocytic lymphohistiocytosis with CNS involvement treated at 2 pediatric neurology centers between 2010 and 2018. Clinical and MR imaging data were analyzed.

RESULTS

Fifty-seven children (40 primary, 70%) with a median age of 36 months (interquartile range, 5.5-80.8 months) were included. One hundred twenty-three MR imaging studies were assessed, and 2 broad imaging patterns were identified. Pattern 1 (significant parenchymal disease, 32/57, 56%) was seen in older children (P = .004) with worse clinical profiles. It had 3 onset subpatterns: multifocal white matter lesions (21/32, 66%), brainstem predominant disease (5, 15%), and cerebellitis (6, 19%). All patients with the brainstem pattern failed to meet the radiologic criteria for chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids. An attenuated imaging phenotype (pattern 2) was seen in 25 patients (44%, 30 studies) and was associated with younger age.

CONCLUSIONS

Distinct MR imaging patterns correlating with clinical phenotypes and possible genetic underpinnings were recognized in this cohort of pediatric CNS hemophagocytic lymphohistiocytosis. Disruptive mutations and missense mutations with absent protein expression correlate with a younger onset age. Children with brainstem and cerebellitis patterns and a negative etiologic work-up require directed assessment for CNS hemophagocytic lymphohistiocytosis.

Progressive myoclonic epilepsy due to rare mitochondrial ND6 mutation, m.14487T>C

Introduction

Mitochondrial diseases exhibit wide phenotypic heterogeneity, and can present as progressive myoclonic epilepsy.

Summary

We report a case of adult-onset drug-resistant epilepsy, cortical myoclonus and bilateral optic neuropathies due to m.14487T>C, a rare mitochondrial gene mutation identified on whole-genome sequencing. This mutation, which affects the NADH dehydrogenase 6 (ND6) subunit of the mitochondrial respiratory chain, is most commonly implicated in cases of infantile-onset Leigh syndrome, although a broader phenotypic spectrum including migraine with aura and progressive myoclonic epilepsy have been described. Serial MRI scans over a 2-year period demonstrated the interval development of bihemispheric stroke-like lesions. Giant somatosensory evoked potentials and short-duration myoclonic jerks with craniocaudal spread on surface electromyography were consistent with cortical myoclonus. Optical coherence tomography showed bilateral symmetric thinning of the nerve fibre layer in the papillomacular bundles.

Conclusion

Whole-genome sequencing can help to provide a definitive diagnosis for mitochondrial disease and should be considered in situations where clinical suspicion remains high despite normal genetic panels or muscle histopathology. Mitochondrial disease can present as adult-onset progressive myoclonic epilepsy, and bilateral optic neuropathies can be a striking feature of ND6 mitochondrial gene mutations. In our case, severe cortical myoclonus affecting speech and swallowing remained highly drug-resistant, however, symptomatic benefit was derived from targeted onabotulinum toxin A injections.

Ectopic thoracic meningioma: a diagnostically challenging case

Whilst meningiomas are common neoplasms of the central nervous system; ectopic meningiomas are very rare. When they do occur, they are typically in the head and neck. Due to their rarity, they propose a diagnostic challenge with interesting pathological findings. To date, only seven ectopic meningiomas arising in the mediastinum have been reported in the literature. We aim to shift the focus on the diagnostic journey of this rare entity which involved various imaging and histopathological techniques. Our patient was successfully treated with no complications after four years through input from specialists and the multidisciplinary team.

Differential Diagnoses of Inclusion Body Myositis

Inclusion body myositis is a slowly progressive myopathy, characteristically affecting quadriceps and long finger flexors. Atypical presentations do occur, however, and there is overlap with other myopathies, including inflammatory and hereditary etiologies. This article discusses atypical cases and differential diagnoses and considers the role of imaging and histopathology in differentiating inclusion body myositis.

DNA methylation-based profiling for paediatric CNS tumour diagnosis and treatment: a population-based study

BACKGROUND

Marked variation exists in the use of genomic data in tumour diagnosis, and optimal integration with conventional diagnostic technology remains uncertain despite several studies reporting improved diagnostic accuracy, selection for targeted treatments, and stratification for trials. Our aim was to assess the added value of molecular profiling in routine clinical practice and the impact on conventional and experimental treatments.

METHODS

This population-based study assessed the diagnostic and clinical use of DNA methylation-based profiling in childhood CNS tumours using two large national cohorts in the UK. In the diagnostic cohort-which included routinely diagnosed CNS tumours between Sept 1, 2016, and Sept 1, 2018-we assessed how the methylation profile altered or refined diagnosis in routine clinical practice and estimated how this would affect standard patient management. For the archival cohort of diagnostically difficult cases, we established how many cases could be solved using modern standard pathology, how many could only be solved using the methylation profile, and how many remained unsolvable.

FINDINGS

Of 484 patients younger than 20 years with CNS tumours, 306 had DNA methylation arrays requested by the neuropathologist and were included in the diagnostic cohort. Molecular profiling added a unique contribution to clinical diagnosis in 107 (35%; 95% CI 30-40) of 306 cases in routine diagnostic practice-providing additional molecular subtyping data in 99 cases, amended the final diagnosis in five cases, and making potentially significant predictions in three cases. We estimated that it could change conventional management in 11 (4%; 95% CI 2-6) of 306 patients. Among 195 historically difficult-to-diagnose tumours in the archival cohort, 99 (51%) could be diagnosed using standard methods, with the addition of methylation profiling solving a further 34 (17%) cases. The remaining 62 (32%) cases were unresolved despite specialist pathology and methylation profiling.

INTERPRETATION

Together, these data provide estimates of the impact that could be expected from routine implementation of genomic profiling into clinical practice, and indicate limitations where additional techniques will be required. We conclude that DNA methylation arrays are a useful diagnostic adjunct for childhood CNS tumours.

FUNDING

The Brain Tumour Charity, Children with Cancer UK, Great Ormond Street Hospital Children's Charity, Olivia Hodson Cancer Fund, Cancer Research UK, and the National Institute of Health Research.

Choroid plexus papillomas are induced by c-Myc overexpression in the choroid plexus via a T-cell inflammatory mechanism

Choroid plexus tumours (CPT) account for up to 20% of brain tumours in children under 2 years of age. Histologically CPTs are classified into three categories - Choroid Plexus Papilloma (CPP), Atypical Choroid Plexus Papilloma (ACPP) and Choroid Plexus Carcinoma (CPC). Recent literature demonstrates that CPP and ACPP are molecularly distinct from CPC. Initial management for CPT include surgery followed by adjuvant therapy in selected patients. Currently there are no disease-specific chemotherapeutic agents available, possibly because of their rarity and paucity of faithful pre-clinical experimental models.

In this study we show that c-Myc overexpression in the choroid plexus epithelium induces T-cell inflammation-dependent choroid plexus papillomas in a mouse model. We demonstrate that c-MYC is expressed in a substantial proportion of human choroid plexus tumours and that this subgroup of tumours is characterised by an inflammatory transcriptome and significant inflammatory infiltrates. We observed that triple transgenic compound mutant mouse model with c-Myc overexpression in an immune-suppressed background led to a decreased incidence of CPP and reduced tumour bulk. A reduced tumour size was also observed when c-Myc overexpressing mice were treated with anti-CD3 antibodies.

Our data raise the possibility that benign choroid plexus tumours expressing c-MYC could be amenable to medical therapy with anti-inflammatory drugs.

Recurrent Langerhans cell histiocytosis at the site of prior craniotomy: case report

Tumors of the CNS represent the largest group of solid tumors found in the pediatric patient population. Langerhans cell histiocytosis (LCH) is an inflammatory lesion that may present in bone and/or soft tissue, including the CNS. Management depends on the extent of multisystem involvement, which determines resection with or without systemic chemotherapy. The authors report on the case of a child who underwent an open craniotomy for biopsy of a pituitary stalk lesion followed by neuropathological assessment, procedures used to diagnose LCH. The patient then underwent 12 months of systemic chemotherapy with subsequent resolution of the pituitary stalk lesion. Two years following pathological diagnosis, the patient presented with frontal orbital pain at the site of the prior craniotomy. Advanced imaging revealed MRI enhancement and radiotracer uptake of a soft-tissue growth at the frontal burr-hole site and MRI enhancement at a posterior burr-hole site without soft-tissue growth. The patient then underwent open biopsy and curettage that revealed LCH recurrence at the site of prior craniotomy. This case demonstrates that LCH may represent an abnormal reactive clonal proliferation of dendritic cells, rather than a de novo malignant neoplasm that can occur at sites of prior craniotomy despite systemic chemotherapy. The authors advocate close follow-up with contrast-enhanced imaging. Special attention should be given to sites of prior surgical manipulation to avoid missing distant sites of recurrence.

c-MYC overexpression induces choroid plexus papillomas through a T-cell mediated inflammatory mechanism

Choroid plexus tumours (CPTs) account for 2–5% of brain tumours in children. They can spread along the neuraxis and can recur after treatment. Little is known about the molecular mechanisms underlying their formation and only few high fidelity mouse models of p53-deficient malignant CPTs are available.

We show here that c-MYC overexpression in the choroid plexus epithelium induces T-cell inflammation-dependent choroid plexus papillomas in a mouse model. We demonstrate that c-MYC is expressed in a substantial proportion of human choroid plexus tumours and that this subgroup of tumours is characterised by an inflammatory transcriptome and significant inflammatory infiltrates. In compound mutant mice, overexpression of c-MYC in an immunodeficient background led to a decreased incidence of CPP and reduced tumour bulk. Finally, reduced tumour size was also observed upon T-cell depletion in CPP-bearing mice. Our data raise the possibility that benign choroid plexus tumours expressing c-MYC could be amenable to medical therapy with anti-inflammatory drugs.

Integrated phenotype-genotype approach in diagnosis and classification of common central nervous system tumours

After nearly a century of histological classification of central nervous system tumours, the 2016 revised WHO classification has incorporated molecular features with clinical and prognostic relevance into brain tumour classification. In this review, we discuss the latest integrated phenotype-genotype approach to the most common intrinsic brain tumours in adults and children. The key genetic mutations and abnormalities, essential to the definition of these tumours, in line with the current WHO classification are described. Practical dilemmas, including 'difficult' tumours, the utility of DNA methylation classifiers and relevant recent advances post-WHO 2016 consensus are also discussed.

Convergence of BMI1 and CHD7 on ERK Signaling in Medulloblastoma

We describe molecular convergence between BMI1 and CHD7 in the initiation of medulloblastoma. Identified in a functional genomic screen in mouse models, a BMI1High;CHD7Low expression signature within medulloblastoma characterizes patients with poor overall survival. We show that BMI1-mediated repression of the ERK1/2 pathway leads to increased proliferation and tumor burden in primary human MB cells and in a xenograft model, respectively. We provide evidence that repression of the ERK inhibitor DUSP4 by BMI1 is dependent on a more accessible chromatin configuration in G4 MB cells with low CHD7 expression. These findings extend current knowledge of the role of BMI1 and CHD7 in medulloblastoma pathogenesis, and they raise the possibility that pharmacological targeting of BMI1 or ERK may be particularly indicated in a subgroup of MB with low expression levels of CHD7.

Multiple brain abscesses caused by Rhinocladiella mackenziei in an immunocompetent patient: a case report and literature review

Primary cerebral phaeohyphomycosis due to Rhinocladiella mackenziei is an extremely rare infection carrying more than 80% mortality, with most cases reported from the Middle East region. This darkly pigmented black yeast is highly neurotropic, aggressive and refractory to most antifungal agents. Here we present an immunocompetent elderly male, presenting with multiple brain abscesses, with R. mackenziei confirmed by nuclear ribosomal repeat region sequencing, who was successfully treated by surgical debridement and intravenous voriconazole. To our knowledge this is the first case reported from the United Kingdom. We also present a review of all such cases so far reported in the English literature world-wide, which we believe is a step further to understanding the pathogenesis and establishing effective treatment of this rare, yet often fatal disease.

Intracranial papillary endothelial hyperplasia (Masson's tumour) following gamma knife radiosurgery for temporal lobe epilepsy

We present a rare case of intracranial papillary endothelial hyperplasia, or 'Masson's tumour,' following gamma knife radiosurgery for epilepsy. A 59-year-old woman presented with a 4-month history of escalating headaches and progressive neurological deficit. MR scan of brain showed enlargement of an enhancing right temporal lobe lesion, midline shift and obstructive hydrocephalus. She had previously undergone non-curative gamma knife radiosurgery at the age of 44 years for medically refractory complex partial seizures. Postprocedure imaging had shown signal change and enhancement within the right temporal lobe consistent with radiation necrosis, which remained stable over the next decade. Now, 15 years following radiosurgery, we suspected an intrinsic high-grade neoplasm, but surgical excision instead found a benign pseudoneoplasm. Papillary endothelial hyperplasia should be considered in the differential diagnosis for mass lesions following gamma knife radiosurgery, particularly as resection can be curative. Remarkably, she has become seizure free.

Drug-Repositioning Screens Identify Triamterene as a Selective Drug for the Treatment of DNA Mismatch Repair Deficient Cells

Purpose: The DNA mismatch repair (MMR) pathway is required for the maintenance of genome stability. Unsurprisingly, mutations in MMR genes occur in a wide range of different cancers. Studies thus far have largely focused on specific tumor types or MMR mutations; however, it is becoming increasingly clear that a therapy targeting MMR deficiency in general would be clinically very beneficial.Experimental Design: Based on a drug-repositioning approach, we screened a large panel of cell lines with various MMR deficiencies from a range of different tumor types with a compound drug library of previously approved drugs. We have identified the potassium-sparing diuretic drug triamterene, as a novel sensitizing agent in MMR-deficient tumor cells, in vitro and in vivoResults: The selective tumor cell cytotoxicity of triamterene occurs through its antifolate activity and depends on the activity of the folate synthesis enzyme thymidylate synthase. Triamterene leads to a thymidylate synthase-dependent differential increase in reactive oxygen species in MMR-deficient cells, ultimately resulting in an increase in DNA double-strand breaks.Conclusions: Conclusively, our data reveal a new drug repurposing and novel therapeutic strategy that has potential for the treatment of MMR deficiency in a range of different tumor types and could significantly improve patient survival. Clin Cancer Res; 23(11); 2880-90. ©2016 AACR.

CD8+ encephalitis: a severe but treatable HIV-related acute encephalopathy

Rapidly progressive encephalopathy in an HIV-positive patient presents a major diagnostic and management challenge. CD8+ encephalitis is a severe but treatable form of HIV-related acute encephalopathy, characterised by diffuse perivascular and intraparenchymal CD8+ lymphocytic infiltration. It can occur in patients who are apparently stable on antiretroviral treatment and probably results from viral escape into the central nervous system. Treatment, including high-dose corticosteroids, can give an excellent neurological outcome, even in people with severe encephalopathy and a very poor initial neurological status. We report a woman with CD8+ encephalitis, with a normal CD4 count and undetectable serum viral load, who made a good recovery despite the severity of her presentation.

Venous infarction mimicking a neoplasm in spontaneous intracranial hypotension: an unusual cause of Parinaud's syndrome

We present a case of longstanding, undiagnosed spontaneous intracranial hypotension (SIH) with an acute presentation of Parinaud's syndrome, in whom serial imaging demonstrated development of a midbrain mass. The patient was ultimately diagnosed with tumefactive venous infarction secondary to SIH. However, this patient underwent a brainstem biopsy, which in retrospect may have been avoidable. This case demonstrates the imaging features of tumefactive venous infarction in SIH and highlights the risk of misinterpretation as a neoplasm with potentially catastrophic consequences.

Ectopic liver tissue in the kidney: case report and literature review

The presence of ectopic liver tissue has been reported in various abdominal and extra-abdominal sites, most often in the gall bladder. Other rare sites include the retroperitoneum and the adrenal gland, which are anatomically closer to the kidney. However, our literature search did not reveal any reports of ectopic liver tissue within the kidney. We present such a case, detected incidentally during a fetal autopsy histologic examination, and we review the possible developmental aspects causing it. Ectopic liver is usually asymptomatic, although it can carry pathology similar to the orthotopic liver. It can be associated with other congenital anomalies and, rarely, can be the cause for clinical emergencies. The most significant implication, however, is development of hepatocellular carcinoma because of an increased predisposition compared with the native liver. Hence, we suggest that ectopic liver in the kidney should be considered by histopathologists, even in unsuspecting cases.

Polycomb group gene BMI1 controls invasion of medulloblastoma cells and inhibits BMP-regulated cell adhesion

Background

Medulloblastoma is the most common intracranial childhood malignancy and a genetically heterogeneous disease. Despite recent advances, current therapeutic approaches are still associated with high morbidity and mortality. Recent molecular profiling has suggested the stratification of medulloblastoma from one single disease into four distinct subgroups namely: WNT Group (best prognosis), SHH Group (intermediate prognosis), Group 3 (worst prognosis) and Group 4 (intermediate prognosis). BMI1 is a Polycomb group repressor complex gene overexpressed across medulloblastoma subgroups but most significantly in Group 4 tumours. Bone morphogenetic proteins are morphogens belonging to TGF-β superfamily of growth factors, known to inhibit medulloblastoma cell proliferation and induce apoptosis.

Results

Here we demonstrate that human medulloblastoma of Group 4 characterised by the greatest overexpression of BMI1, also display deregulation of cell adhesion molecules. We show that BMI1 controls intraparenchymal invasion in a novel xenograft model of human MB of Group 4, while in vitro assays highlight that cell adhesion and motility are controlled by BMI1 in a BMP dependent manner.

Conclusions

BMI1 controls MB cell migration and invasion through repression of the BMP pathway, raising the possibility that BMI1 could be used as a biomarker to identify groups of patients who may benefit from a treatment with BMP agonists.

Prospective technical validation and assessment of intra-tumour heterogeneity of a low density array hypoxia gene profile in head and neck squamous cell carcinoma

BACKGROUND AND PURPOSE

Tumour hypoxia is associated with a poor prognosis in head and neck squamous cell carcinoma (HNSCC), however there is no accepted method for assessing hypoxia clinically. We aimed to conduct a technical validation of a hypoxia gene expression signature using the TaqMan Low Density Array (TLDA) platform to investigate if this approach reliably identified hypoxic tumours.

MATERIALS AND METHODS

Tumour samples (n=201) from 80 HNSCC patients were collected prospectively from two centres. Fifty-three patients received pimonidazole prior to surgery. TaqMan Low Density Array-Hypoxia Scores (TLDA-HS) were obtained by quantitative real-time PCR (qPCR) using a 25-gene signature and customised TLDA cards. Assay performance was assessed as coefficient of variation (CoV).

RESULTS

The assay was sensitive with linear reaction efficiencies across a 4 log(10) range of inputted cDNA (0.001-10 ng/μl). Intra- (CoV=6.9%) and inter- (CoV=2.0%) assay reproducibility were excellent. Intra-tumour heterogeneity was lower for TLDA-HS (23.2%) than for pimonidazole (67.2%) or single gene measurements of CA9 (62.2%), VEGFA (45.0%) or HIG2 (39.4%). TLDA-HS in HNSCC cell lines increased with decreasing pO(2). TLDA-HS correlated with Affymetrix U133 Plus 2.0 microarray HS (p<0.01) and positive pimonidazole scores (p=0.005).

CONCLUSIONS

Gene expression measurements of hypoxia using a 25-gene signature and TLDA cards are sensitive, reproducible and associated with lower intra-tumour heterogeneity than assaying individual genes or pimonidazole binding. The approach is suitable for further assessment of prognostic and predictive capability in clinical trial material.

Lack of prognostic effect of carbonic anhydrase-9, hypoxia inducible factor-1α and bcl-2 in 286 patients with early squamous cell carcinoma of the glottic larynx treated with radiotherapy

AIMS

To evaluate the prognostic significance of potential tumour markers of hypoxia and apoptosis in early squamous cell carcinoma of the glottic larynx managed with radiotherapy.

MATERIALS AND METHODS

In total, 382 patients with T1 and T2 squamous cell carcinoma of the glottic larynx (vocal cords) received radical radiotherapy (50-55 Gy, in 16 fractions in 98% of cases). Pre-treatment haemoglobin was available for 328 patients; biopsy samples were available for 286. Immunohistochemistry was carried out for carbonic anhydrase-9 (CA-9), hypoxia inducible factor-1α (HIF-1α) and Bcl-2.

RESULTS

At 5 years, locoregional control was achieved in 88.2%, cancer-specific survival in 95.0% and overall survival in 78.7%. Adverse prognostic factors for locoregional tumour recurrence were pre-treatment haemoglobin <13.0 g/dl (P = 0.035, Log rank test; sensitivity 0.28, specificity 0.84) and stage T2 rather than T1 (P = 0.002). The effect of haemoglobin level on locoregional control was not significant when stratified by the median of 14.2 g/dl (P = 0.43) or as a continuous variable (P = 0.59). High CA-9 (P = 0.11), HIF-1α (P = 0.67) and Bcl-2 (P = 0.77) expression had no prognostic significance.

CONCLUSIONS

High CA-9, HIF-1α and Bcl-2 do not add to the prognostic significance of tumour stage and lower haemoglobin in predicting failure of local control in early glottic larynx squamous cell carcinoma managed with radiotherapy. The effect of haemoglobin was not strong enough to be useful as a prognostic biomarker.

Abstract LB-440: Low density array profiling of head and neck squamous cell carcinoma utilizing a 25-gene signature can reliably identify hypoxic tumors

Purpose: Administering hypoxia modifying therapy to patients with head and neck squamous cell carcinoma (HNSCC) improves outcomes in those with identified hypoxic tumors. As no method for measuring tumor hypoxia has demonstrated clinical utility, this study aimed to validate use of a gene expression signature with a TaqMan Low Density Array (TLDA) platform. Experimental design: Tumor samples (n=201) from 80 HNSCC patients were collected prospectively from two centers. Fifty-three patients received pimonidazole prior to surgery. Hypoxia scores (TLDA HS) were obtained by quantitative real-time PCR (qPCR) using a 25-gene signature and customized TLDA cards. Assay performance was assessed as coefficient of variation (CoV). Relationships with outcome were determined by log-rank analysis. Results: The assay was sensitive with linear reaction efficiencies across a 4log10 range of inputted cDNA (0.001-10 ng/µl). Intra- (CoV=0.5%) and inter- (CoV=0.1%) assay reproducibility were excellent. Intra-tumor heterogeneity was lower for TLDA HS (23.2%) than for pimonidazole (67.2%) or single gene measurements of CA9 (62.2%), VEGFA (45.0%) or HIG2 (39.4%). TLDA HS in HNSCC cell lines increased with decreasing pO2 and was reduced but not completely abrogated in HIF1A silenced cells. TLDA HS correlated with Affymetrix U133 Plus 2.0 microarray HS (p&lt;0.01) and pimonidazole scores (p=0.021). High TLDA HS was associated with worse overall (p=0.037) and recurrence free (p=0.036) survival. Conclusions: Gene expression measurements of hypoxia using a 25-gene signature and TLDA cards are sensitive, reproducible and associated with lower intra-tumor heterogeneity than assaying individual genes or pimonidazole binding. The approach is suitable for application in clinical trials.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-440. doi:1538-7445.AM2012-LB-440