Tuberous sclerosis complex neuropathology requires glutamate-cysteine ligase

Introduction: Tuberous sclerosis complex (TSC) is a genetic disease resulting from mutation in TSC1 or TSC2 and subsequent hyperactivation of mammalian Target of Rapamycin (mTOR). Common TSC features include brain lesions, such as cortical tubers and subependymal giant cell astrocytomas (SEGAs). However, the current treatment with mTOR inhibitors has critical limitations. We aimed to identify new targets for TSC pharmacotherapy. Results: The results of our shRNA screen point to glutamate-cysteine ligase catalytic subunit (GCLC), a key enzyme in glutathione synthesis, as a contributor to TSC-related phenotype. GCLC inhibition increased cellular stress and reduced mTOR hyperactivity in TSC2-depleted neurons and SEGA-derived cells. Moreover, patients’ brain tubers showed elevated GCLC and stress markers expression. Finally, GCLC inhibition led to growth arrest and death of SEGA-derived cells. Conclusions: We describe GCLC as a part of redox adaptation in TSC, needed for overgrowth and survival of mutant cells, and provide a potential novel target for SEGA treatment. Electronic supplementary material The online version of this article (doi:10.1186/s40478-015-0225-z) contains supplementary material, which is available to authorized users

Heterogeneity of histopathological presentation of pilocytic astrocytoma – diagnostic pitfalls. A review

Pilocytic astrocytomas (PAs) are the most frequent primary astroglial tumours affecting children and adolescents. They occur sporadically or in association with a genetically determined syndrome – neurofibromatosis type 1. Classic PA usually manifests as a well-circumscribed, often cystic, slowly growing tumour, which corresponds to WHO grade I. The majority of pilocytic tumours arise along the neuraxis, predominantly in the cerebellum. They are associated with favourable long-term outcome or spontaneous regression, even after incomplete resection. However, the behaviour and prognosis might also be related to tumour histology and location. Pilomyxoid astrocytoma (PMA) represents a variant of classical PA with more invasive growth and increased risk of recurrences and dissemination. Typically, PAs exhibit distinct histology with biphasic architecture of loose, microcystic and compact, fibrillary areas. However, some tumours arise in an uncommon location and display heterogeneous histopathological appearance. The morphological pattern of PA can mimic some other glial neoplasms, including oligodendroglioma, pleomorphic xanthoastrocytoma, ependymoma or diffuse astrocytoma. Not infrequently, the advanced degenerative changes, including vascular fibrosis, and recent and old haemorrhages, may mimic vascular pathology. Sometimes, the neoplastic piloid tissue can resemble reactive gliosis, related to long-standing non neoplastic lesions. Not infrequently, PA exhibits histological features typical for anaplasia, including necrosis, mitoses and glomeruloid vascular proliferation that can suggest a diffuse high-grade glioma. However, even those PAs that lack distinct histological features of anaplasia can behave unpredictably, in a more aggressive manner, with leptomeningeal spreading. Genetic alterations resulting in aberrant signalling of the mitogen-activated protein kinase (MAPK) pathway have been considered to underlie the development of PAs. The most commonly identified KIAA1549-BRAF fusion is important for appropriate tumour molecular diagnosis. In this paper we summarize the clinicopathological presentation of PAs, with emphasis on their heterogeneous morphology, based on our own experience in the field of surgical neuropathology and the literature data. Diagnosis of pilocytic tumours requires careful analysis of clinical, histopathological and molecular features to avoid misinterpretation of these benign neoplastic lesions

Dysembryoplastic neuroepithelial tumour: insight into the pathology and pathogenesis

Dysembryoplastic neuroepithelial tumour (DNT) is categorized as a benign glioneuronal neoplasm affecting children and young adults with chronic epileptic seizures. It is characterized by predominant intracortical localization and nodular architecture. Dysembryoplastic neuroepithelial tumour usually demonstrates a distinctive morphological pattern with a specific glioneuronal element but occasionally, its morphological picture is heterogeneous and unspecific. Thus, considering the morphology of DNT, three different histopathological subtypes are distinguished: simple, complex, and non-specific and diffuse. The DNT lesions are often related with focal cortical dysplasia (FCD) type IIIb, which is postulated to play a role in epileptogenicity. Moreover, the accompanying inflammation process might be implicated in DNT-related epileptogenesis. Dysembryoplastic neuroepithelial tumour is generally characterized by favourable prognosis and good results of surgical treatment. The pathogenesis and molecular mechanisms involved in DNT development remain uncertain. The main molecular findings are connected with BRAF alterations and activation of RAS/ERK, PI3K/AKT and mTOR signalling pathways. The present review summarizes the clinical, histopathological and molecular findings of DNT. The classification controversy, morphological heterogeneity and diagnostic problems are also discussed

Central nervous system autopsy — a neuropathological procedure based on multidisciplinary pathoclinical cooperation

Introduction: Neuropathological brain and spinal cord post mortem examination is a distinct procedure that still plays an important role in modern medicine. In front of increasing amounts of clinical and genetic data, together with important developments in the field of neuroimaging, the Polish Association of Neuropathologists have updated their recommendations regarding central nervous system (CNS) examination. These guidelines are aimed at neuropathologists, pathologists and clinicians.Aim of the study: Presentation of the outlined recommendations as their goal is to improve the quality, informativity, and cost effectiveness of CNS post mortem examinations. A comprehensive study of the literature was conducted to provide a clinical background of neuropathological autopsy. There are numerous open questions in neuroscience, and new strategies are required to foster research in CNS diseases. These include the challenge of organizing brain banks tasked with managing and protecting detailed multidisciplinary information about their resources. Complex neuropathological analyses of post mortem series are also important to assess the effectiveness of diagnostics and therapy, identify environmental impact on the development of neurological disorders, and improve public health policy. The recommendations outline the need for collaboration between multiple specialists to establish the proper diagnosis and to broaden knowledge of neurological disorders

Recommendations of the Polish Association of Neuropathologists on performing post-mortem examination of the brain and spinal cord

Neuropathological central nervous system (CNS) post-mortem examination is a highly specialistic element of the autopsy procedure with methodological specificity. Herein we propose updated recommendations for CNS autopsy for pathologists and neuropathologists. The protocol includes the compendium of neuroanatomy with current nomenclature, consecutive steps of gross examination, as well as appropriate sampling algorithms in different clinical and pathological settings. The significance of pathoclinical cooperation in differential diagnosis is exposed. We believe it is essential to create and promote the guidelines to improve the quality of CNS post-mortem examination at the national level