Neuropathology最新文献

Multiple sclerosis (MS), the leading cause of disability in young adults, is an inflammatory disease of the central nervous system characterized by localized areas of demyelination. Apoptosis signal-regulating kinase 1 (ASK1) is a mitogen-activated protein kinase kinase kinase that has been shown to be implicated in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. Interestingly, ASK1 signaling regulates glial cell interactions and drives neuroinflammation in EAE mice. To further investigate its clinical significance, in the present study, we examined the activation of ASK1 in the post-mortem brain of MS patients. ASK1 activation was found in active lesions of the corpus callosum in both microglia/macrophages and astrocytes. Moreover, ASK1 activation in astrocytes was higher than that in microglia/macrophages, which was in line with our findings in EAE mice. Our results suggest an important role of ASK1 in glial cells, indicating that ASK1 might be a good therapeutic target for MS.

In the fifth edition of the World Health Organization's (WHO) classification of tumors of the central nervous system (CNS), molecular analysis is required for not only determining each tumor type but assessing its prognosis based on malignancy (CNS WHO grade). A notable example is the loss of tumor suppressor gene cyclin-dependent kinase inhibitor 2A (CDKN2A), and CDKN2A homozygous deletion (HD) is a novel CNS WHO grade 4 marker in isocitrate dehydrogenase gene (IDH)-mutant astrocytoma. However, incorporating molecular workup into the "routine diagnostics" of each brain tumor type remains a major challenge, especially in resource-limited settings, including low- and middle-income countries. We herein validated the usefulness of p16 and methylthioadenosine phosphorylase (MTAP) immunohistochemistry (IHC) as potential surrogates for the assessment of CDKN2A status in 20 IDH-mutant astrocytoma cases. Of note, loss or retention of p16 and MTAP could accurately predict CDKN2A HD (p16: 87.5%, MTAP: 88.9%) or non-HD (p16: 100%, MTAP: 100%) with a single marker alone. Importantly, we revealed contributing factors to gray-zone IHC results (p16: 5-20%, MTAP: mosaic), including (1) hemizygous deletion of CDKN2A, (2) degenerative findings, and (3) intratumoral CDKN2A HD heterogeneity, the detailed histologic and molecular assessment of which would be a key to achieving integrated assessment of malignancy in IDH-mutant astrocytoma. We characterized the pitfalls of each method and provided for the first time a practical flowchart of astrocytoma grading, contributing to a normalization of WHO2021-based molecular diagnostics in resource-limited settings.

We report a rare case of rhabdoid meningioma (RM) originating from the optic nerve in a 57-year-old female. The tumor exhibited rhabdoid or epithelioid histology and harbored BAP1 inactivation mutations. Optic nerve meningioma typically originates from the outer meningeal cells of the optic nerve within the optic canal and is usually benign, with most cases classified as meningothelial or transitional meningiomas. This is the first reported case of RM involving the optic nerve, presenting with World Health Organization (WHO) central nervous system (CNS) grade 1 histological features but without CDKN2A/B homozygous deletions or telomerase reverse transcriptase promoter mutations, though harboring a BAP1 deletion. Despite being classified as a low-grade tumor by current standards, the rapid recurrence and progression observed underscore the importance of reporting this case to enhance awareness among pathologists and reduce misdiagnoses.

Embryonal tumors with multilayered rosettes (ETMRs) are rare and highly aggressive embryonal central nervous system tumors that predominantly affect infants younger than 3 years old. These tumors typically have a C19MC alteration (ETMR, C19MC-altered) or, more rarely, a DICER1 mutation (ETMR, DICER1-mutated). Post-chemotherapeutic or post-chemoradiotherapeutic histological changes of C19MC-altered ETMRs, such as maturation or loss of histological characteristics of ETMR have been described in several reports. However, histological changes of recurrent DICER1-mutated ETMRs have not been reported to date. Herein, we report a case of DICER1-mutated ETMR with unique post-treatment morphological changes, including both maturation and loss of histological characteristics. Although pathological examination of tissue from the first resection revealed typical ETMR histology, the recurrent tumor after chemoradiotherapy was composed predominantly of a primitive embryonal component without multilayered rosettes or neuropil-like areas. Furthermore, the recurrent tumor contained a component composed of unique tumor cells with oval eccentric nuclei and eosinophilic cytoplasm demonstrating a neuronal immunohistohemical phenotype. No mitotic figures were found in the component. Molecular analysis identified a mutation in the DICER1 RNase IIIb domain in the primary tumor and the primitive embryonal component of the recurrent tumor, but not in the unique neuronal area.

The degeneration of pyramidal tracts has been reported in frontotemporal lobar degeneration with TDP-43 (TAR DNA-binding protein 43) pathology (FTLD-TDP) type C. Herein, we examined the detailed pathology of the primary motor area and pyramidal tracts in the central nervous system in four autopsy cases of FTLD-TDP type C, all of which were diagnosed by neuropathological, biochemical, and genomic analyses. Three patients showed right dominant atrophy of the frontal and temporal lobes, while the other patient showed left dominant atrophy. All four patients showed motor symptoms, and two patients had episodes of repeated aspiration. In the primary motor area, phosphorylated TDP-43 (p-TDP-43) or annexin A11-immunoreactive long dystrophic neurites were observed in all cases, and neuronophagia of the Betz cells was frequently observed in two of four cases. In the lower motor system, p-TDP-43 or annexin A11-positive dystrophic neurites were detected in the anterior horn of the spinal cord. Immuno-electron microscopy of the insoluble fraction extracted from all cases showed p-TDP-43 or annexin A11-labelled filaments. In FTLD-TDP type C, neurodegeneration with TDP and annexin A11 pathology was observed mainly in the upper motor neurons of both patients with right- and left predominant temporal atrophy and a short disease duration. Furthermore, a combination of TDP-43 and annexin A11 pathology was visible in the lower motor neurons, albeit less frequently. In summary, we reported the TDP-43 and annexin A11-associated involvement of anterior horn cells of the spinal cord for the first time. The degeneration of the motor system could contribute to dysphagia and aspiration pneumonia at the late stage of FTLD-TDP type C. Little or no TDP pathology was found in the corticospinal tract, unlike in FTLD-TDP type B, suggesting the occurrence of secondary degeneration in FTLD-TDP type C.

The manifestation of glioblastoma, IDH-wildtype (GB) as intracranial hemorrhage (ICH) presents diagnostic and therapeutic challenges. Molecular characteristics, including TERT promoter mutation, EGFR amplification, and chromosome 7 gain/10 loss, were incorporated to diagnose GB in the fifth edition of the World Health Organization Classification of Tumors of the Central Nervous System. When molecular analyses fail to detect low fractions of these genetic alterations, the integrated diagnosis of GB can be enigmatic. This case report describes a 58-year-old man presenting with ICH, masking an underlying GB. Initial histopathology of the evacuated hematoma revealed a small number of atypical glial cells, but a definitive diagnosis was deferred. Subsequent surgery and molecular analysis, including digital polymerase chain reaction (dPCR), confirmed the presence of a TERT C228T mutation in the promoter area, leading to an integrated diagnosis of GB. The patient experienced a favorable clinical outcome following surgery, radiation, temozolomide, and tumor-treating field therapy, without recurrence after 50 months. This case underscores the importance of meticulous histological examination of ICH and exemplifies the clinical utility of dPCR as a complementary diagnostic tool. The effectiveness of dPCR is particularly noteworthy, even in scenarios with minimal tumor cell content, reinforcing its value in the integrated diagnosis of GB.

This report details a rare case of a 30-year-old female presenting with neurological symptoms, including headaches, seizures, and left-sided weakness. Imaging revealed a mass in the right parafalcine region of her brain. Surgical resection identified a tumor with two distinct components. The first component exhibited characteristics of a classic solitary fibrous tumor (SFT) with typical fibroblastic cells and branching blood vessels. The second component showed high-grade sarcoma with chondrosarcomatous differentiation, a rare feature in SFT. Immunohistochemistry confirmed dedifferentiation with decreased STAT6 expression in the sarcomatous areas compared to the conventional SFT. This case highlights the challenges of managing dedifferentiated SFTs, especially in the brain, where surgical limitations increase risks. Despite the rarity of this presentation, it emphasizes the importance of recognizing this variant for appropriate diagnosis and management.

Solitary fibrous tumors (SFTs) of the central nervous system (CNS) are rare mesenchymal tumors characterized by a fusion of the NGFI-A-binding protein 2 (NAB2) gene and the signal transducer and activator of transcription 6 (STAT6) gene, immunohistochemically resulting in nuclear expression of STAT6 - an immunohistochemical hallmark essential for diagnosis, as outlined in the fifth edition of the World Health Organization Classification of Tumors. Dedifferentiation, where low-grade tumors transform into high-grade forms, has been observed in SFTs, with documented cases involving sarcomatous or rarely epithelial transformations. We report the first case of a CNS SFT exhibiting "transdedifferentiation" into epithelioid neuroendocrine differentiation. A 36-year-old woman presented with worsening frontal headaches and vision deterioration due to an 8.2-cm frontal tumor with skull erosion. Histologically, the tumor consisted of predominantly high-grade undifferentiated epithelioid round cells that expressed STAT6, along with multifocal synaptophysin and chromogranin A positivity, and occasional cytokeratin and claudin-4 reactivity, resembling large cell neuroendocrine carcinoma. A minor bland spindle cell component with STAT 6 immunoreactivity was also noted. This case highlights the rare occurrence of neuroendocrine "transdedifferentiation" in CNS SFTs. This case highlights the importance of recognizing dedifferentiation in CSF SFTs, which often correlates with aggressive tumor behavior and poor prognosis. Given the rarity of neuroendocrine "transdedifferentiation," this case adds valuable insight into the diverse dedifferentiation patterns seen in CNS SFTs, emphasizing the need for accurate diagnosis to guide appropriate treatment strategies.

Multiple system atrophy (MSA) is a rare neurodegenerative disease characterized by an accumulation of phosphorylated α-synuclein (p-αsyn) in oligodendrocytes in the form of glial cytoplasmic inclusions (GCIs). In MSA, not only mature oligodendrocytes but also oligodendrocyte precursor cells (OPCs) are affected. The latter play an important role in remyelination by differentiating into mature oligodendrocytes, as well as maintaining the blood-brain barrier (BBB) by promoting the expression of tight junction proteins. We have hypothesized that in MSA, the BBB is impaired as a result of aberrant interactions between affected OPCs and the cerebral vasculature. To verify this hypothesis, we conducted a neuropathological examination of postmortem brains from MSA patients and control subjects, focusing on the primary motor area, one of the main regions affected in MSA. Using double immunofluorescence, we quantified the expression of tight junction protein claudin-5 in capillary endothelial cells and found that it was significantly lower in MSA than in controls in both the gray matter and white matter. Furthermore, a significantly higher amount of fibrinogen was extravasated into the brain parenchyma in MSA patients than in controls. In addition, leakage of IgG was detected almost specifically in MSA brain parenchyma, as visualized in three dimensions by combining techniques of chemical tissue clearing and light sheet microscopy. Finally, we confirmed accumulation of p-αsyn-positive GCIs along the cerebral vasculature within OPCs. These results suggest that BBB dysfunction and associated fibrinogen extravasation are constant findings in MSA, presumably triggered by the deposition of p-αsyn in perivascular OPCs.