The case for DNA methylation based molecular profiling to improve diagnostic accuracy for central nervous system embryonal tumors (not otherwise specified) in adults.

Central nervous system primitive neuro-ectodermal tumors (CNS-PNETs), have recently been re-classified in the most recent 2016 WHO Classification into a standby catch all category, "CNS Embryonal Tumor, not otherwise specified" (CNS embryonal tumor, NOS) based on epigenetic, biologic and histopathologic criteria. CNS embryonal tumors (NOS) are a rare, histologically and molecularly heterogeneous group of tumors that predominantly affect children, and occasionally adults. Diagnosis of this entity continues to be challenging and the ramifications of misdiagnosis of this aggressive class of brain tumors are significant. We report the case of a 45-year-old woman who was diagnosed with a central nervous system embryonal tumor (NOS) based on immunohistochemical analysis of the patient's tumor at diagnosis. However, later genome-wide methylation profiling of the diagnostic tumor undertaken to guide treatment, revealed characteristics most consistent with IDH-mutant astrocytoma. DNA sequencing and immunohistochemistry confirmed the presence of IDH1 and ATRX mutations resulting in a revised diagnosis of high-grade small cell astrocytoma, and the implementation of a less aggressive treatment regime tailored more appropriately to the patient's tumor type. This case highlights the inadequacy of histology alone for the diagnosis of brain tumours and the utility of methylation profiling and integrated genomic analysis for the diagnostic verification of adults with suspected CNS embryonal tumor (NOS), and is consistent with the increasing realization in the field that a combined diagnostic approach based on clinical, histopathological and molecular data is required to more accurately distinguish brain tumor subtypes and inform more effective therapy.

Cystinosis distal myopathy, novel clinical, pathological and genetic features.

Nephropathic cystinosis is an autosomal recessive lysosomal disease in which cystine cannot exit the lysosome to complete its degradation in the cytoplasm, thus accumulating in tissues. Some patients develop a distal myopathy involving mainly hand muscles. Myopathology descriptions from only 5 patients are available in the literature. We present a comprehensive clinical, pathological and genetic description of 3 patients from 2 families with nephropathic cystinosis. Intrafamiliar variability was detected in one family in which one sibling developed a severe distal myopathy while the other sibling did not show any signs of skeletal muscle involvement. One of the patients was on treatment with Cysteamine for over 12 years but still developed the usual complications of nephropathic cystinosis in his twenties. Novel pathological findings consisting in sarcoplasmic deposits reactive for slow myosin were identified. Three previously known and one novel mutation are reported. Nephropathic cystinosis should be included in the differential diagnosis of distal myopathies in those with early renal failure. Novel clinical and pathological features are reported here contributing to the characterization of the muscle involvement in nephropathic cystinosis.

Novel CHKB mutation expands the megaconial muscular dystrophy phenotype.

INTRODUCTION: Mutations in the choline kinase beta (CHKB) gene are associated with a congenital muscular dystrophy with giant mitochondria at the periphery of muscle fibers. METHODS: We describe a patient of Italian origin in whom whole-exome sequencing revealed a novel homozygous nonsense mutation, c.648C>A, p.(Tyr216*), in exon 5 of CHKB. RESULTS: The patient presented with limb-girdle weakness and hypotonia from birth with mental retardation, and had sudden and transient deteriorations of muscle strength with acute intercurrent illnesses. Previously undescribed sarcolemmal overexpression of utrophin was noted in the muscle biopsy. CONCLUSIONS: Pathological features broaden the description of the entity and provide new insight in the pathogenic mechanisms. This case highlights the usefulness of next-generation sequencing in the diagnosis of rare and incompletely understood conditions.

An analysis of the sensitivity and specificity of MHC-I and MHC-II immunohistochemical staining in muscle biopsies for the diagnosis of inflammatory myopathies.

Although there have been several previous reports of immunohistochemical staining for MHC antigens in muscle biopsies, there appears to be a lack of consensus about its routine use in the diagnostic evaluation of biopsies from patients with suspected inflammatory myopathy. Positive MHC-I staining is nonspecific but is widely used as a marker for inflammatory myopathy, whilst the role of MHC-II staining is not clearly defined. We investigated the sensitivity and specificity of MHC-I and MHC-II immunostaining for the diagnosis of inflammatory myopathy in a large group of biopsies from a single reference laboratory. Positive staining for MHC-I was found to have a high sensitivity in biopsies from patients with inflammatory myopathy but a very low specificity, as it was also common in other non-inflammatory myopathies and neurogenic disorders. On the other hand, MHC-II positivity had a much higher specificity in all major subgroups of inflammatory myopathy, especially inclusion body myositis. The findings indicate that the combination of MHC-I and MHC-II staining results in a higher degree of specificity for the diagnosis of inflammatory myopathy and that in biopsies with inflammation, positive MHC-II staining strongly supports the diagnosis of an immune-mediated myopathy. We recommend that immunohistochemical staining for both MHC-I and MHC-II should be included routinely in the diagnostic evaluation of muscle biopsies from patients with suspected inflammatory myopathy. However, as the sensitivity and interpretation of MHC staining may depend on the technique used, further studies are needed to compare procedures in different centres and develop standardised protocols.

Childhood craniopharyngioma: 20-year institutional experience in Western Australia.

AIM: A retrospective audit was undertaken to evaluate modes of presentation and treatment outcomes for craniopharyngioma in a single paediatric institution over a 20-year period. METHODS: A search of the neurosurgical and histopathological databases for patients under 21 years of age treated for craniopharyngioma between 1990 and 2010 was performed at our institution. The clinical records of eligible patients were reviewed and information regarding presentation, medical and surgical management and post-treatment outcome were extracted and collated. RESULTS: Of 10 evaluable patients, the commonest presenting symptoms were headache and visual impairment. Clinical and biochemical evaluation undertaken prior to surgery revealed visual dysfunction in 70% and pituitary deficit in 30%. Gross total resection was achieved in 40% but was curative in only 20%. The remaining 80% required further surgical and/or radiotherapeutic intervention. Seven patients had radiation therapy with stabilisation in 70%. Multiple pituitary hormone deficiency evolved in all patients over time, while visual impairment worsened in 30% post-operatively and improved in 20%. Obesity was present in 50% after a mean follow-up interval of 5.6 years and was apparent within 1 year of initial surgery in 30%. Although neurocognitive, psychological and behavioural problems were noted for some patients during medical review, only 20% of patients were formally assessed. CONCLUSIONS: Craniopharyngioma is associated with significant long-term morbidity. Attention to an integrated care pathway that includes standardised neurocognitive and psychological and behavioural assessment would facilitate early appropriate intervention and support leading to an improved quality of life for children with craniopharyngioma.

Chemotherapy increases amenability of surgical resection in congenital glioblastoma.

Brain tumors presenting in infancy, especially during the first 6 months of life, are often very large and highly vascular. It is generally accepted that gross total resection of the tumor affords the best outcome to the patient. However, tumor resection is frequently very challenging due to the risk of significant bleeding. We report two cases of congenital glioblastoma whose initial surgery was hampered by tumor hypervascularity and excessive blood loss, resulting in subtotal resection. Subsequent carboplatin-based chemotherapy led to a significant reduction in tumor size and vascularity, enabling safe gross total resection at second-look surgery. Based on these findings and a review of the literature, we recommend cytoreductive chemotherapy following diagnostic biopsy for infants presenting with large, highly vascular tumors, such as congenital glioblastoma, in lieu of aggressive upfront surgery, to increase the feasibility and facilitate safe gross total excision at second-look surgery.

Pediatric meningioma: current approaches and future direction.

With improvement in leukemia therapy, central nervous system (CNS) tumors are the leading cause of cancer mortality in children and the most expensive of all human neoplasms to treat. Meningiomas are rare intracranial tumors in childhood and adolescence arising from arachnoid cell clonal outgrowth in the meninges. There have been no collaborative prospective therapeutic trials for pediatric meningioma because of its rarity, and the best evidence for management comes from retrospective case analyses and extrapolation from the treatment of adult meningioma. However this may not be ideal, because the underlying biology of adult and pediatric meningiomas seems to be different, as is the case for other CNS tumors. In addition, treatment of pediatric brain tumors requires consideration of long-term quality of life. This review reflects on what is currently known about pediatric meningiomas and opportunities for future directions.