Telomere lengthening is one of the key events in most cancers, and depends largely on telomerase activation. Telomerase activation is a well-known phenomenon in gliomas; however, its mechanism remains obscure. In this study, we investigated the presence of mutations in the promoter of the telomerase reverse transcriptase (TERT) gene in a series of 546 gliomas. We found a high incidence of mutually exclusive mutations located at two hot spots, C228T and C250T, in all subtypes of gliomas (55 %). The frequency of mutation was particularly high among primary glioblastomas (70 %) and pure oligodendroglial tumors (74 %), while relatively low in diffuse astrocytomas and anaplastic astrocytomas (19 and 25 %, respectively). The expression level of TERT in tumors carrying those mutations was on average 6.1 times higher than that of wild-type tumors, indicating that the mutated promoter leads to upregulation of TERT. TERT promoter mutations were observed in almost all tumors harboring concurrent total 1p19q loss and IDH1/2 mutations (98 %). Otherwise TERT promoter mutations were mostly observed among IDH wild-type tumors. Most EGFR amplifications (92 %) were also associated with TERT promoter mutations. Our data indicate that mutation of the TERT promoter is one of the major mechanisms of telomerase activation in gliomas. The unique pattern of TERT promoter mutations in relation to other genetic alterations suggests that they play distinct roles in the pathogenesis of oligodendroglial and astrocytic tumors. Our results shed a new light on the role of telomerase activation in the development of adult gliomas.

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Background: Successful multimodality management of advanced soft tissue sarcomas (STS) remains a clinical challenge. Although immune checkpoint blockade has shown great promise, only a minority of patients respond. Improved biomarkers could benefit the treatment choice, since cytotoxic therapies and radiotherapy (RT) can alter the immune milieu. The objective of this study was to characterize PD-L1 expression in locally advanced STS with or without preoperative RT. Design: Tissue microarrays (TMA) were constructed using formalin-fixed, paraffin-embedded STS cases (N=17). A composite H-scoring system was applied to analyze/ quantify the protein expression. TMA sections were immunostained using a rabbit anti-human PD-L1 antibody (Sino Biological, Clone: 015). The intensity and percentage of PDL-1-positive cells were calculated and scored blindly. Patients were categorized into PD-L1 high and low-expressing based on H-score above or below the median. Parametric and non-parametric statistics were used as appropriate. Results: Mean age was 55±21, 82% were female, and 53% of STS tumors were located on the extremity. Median tumor size was 15.5 cm (range 2.4-24.8 cm). Half of the cases received preoperative RT. We observed 9 recurrences, and 5 sarcoma deaths. Overall, PD-L1 expression was significantly lower among RT patients (62.5±23.1 vs 139±90.5, p=0.04), and tumor stem cell markers EGFR/CD44 were also significantly lower among chemotherapy patients (p < 0.05). Distant recurrences were more common in PDL-1 high patients (5/8, 62%) than PDL-1 low patients (2/9, 22%). Conclusions: RT is associated with decreased PD-L1 expression in locally advanced STS, and lower PD-L1 expression is associated with improved longterm outcome. The modulation of PDL-1 expression by RT and the impact on prognosis in STS warrants further study. Background: Dedifferentiated liposarcoma (DDLPS) sometimes exhibit heterologous differentiation, and its influence on prognostic outcome is still controversial. As for ossification, it is also not clear whether the bone component means heterologous differentiation or it can be formed by reactive (non-neoplastic) mesenchymal cells. We aimed to investigate the neoplastic nature of the bones formed in DDLPS, and make clear the clinical and pathological characteristics of DDLPS with ossification. Design: We examined 27 cases of DDLPS with ossification by comparing them with 24 cases of DDLPS without ossification and 17 cases of primary extraskeletal osteosarcoma (ESOS) without MDM2 amplification or overexpression. The clinical and pathological findings were reviewed. Histological grade was determined using 'modified' FNCLCC grading system proposed before emphasizing the importance of tumor differentiation scoring. Results: MDM2 amplification was confirmed in osteocytes and/or osteoblastic cells in all DDLPS cases with ossification where Fluorescence In-Situ Hybridization (FISH) was successfully performed in bone forming area (22/22). The bones found in DDLPS were mainly mature in most cases (20/27), and ...

Introduction: A grading system for pulmonary adenocarcinoma has not been established. The International Association for the Study of Lung Cancer pathology panel evaluated a set of histologic criteria associated with prognosis aimed at establishing a grading system for invasive pulmonary adenocarcinoma. Conclusions: A grading system based on the predominant and high-grade patterns is practical and prognostic for invasive pulmonary adenocarcinoma.

Next‐generation sequencing ( NGS ) of tumor tissue (ie, clinical sequencing) can guide clinical management by providing information about actionable gene aberrations that have diagnostic and therapeutic significance. Here, we undertook a hospital‐based prospective study ( TOP ‐ GEAR project, 2nd stage) to investigate the feasibility and utility of NGS ‐based analysis of 114 cancer‐associated genes (the NCC Oncopanel test). We examined 230 cases (comprising more than 30 tumor types) of advanced solid tumors, all of which were matched with nontumor samples. Gene profiling data were obtained for 187 cases (81.3%), 111 (59.4%) of which harbored actionable gene aberrations according to the Clinical Practice Guidelines for Next Generation Sequencing in Cancer Diagnosis and Treatment (Edition 1.0) issued by 3 major Japanese cancer‐related societies. Twenty‐five (13.3%) cases have since received molecular‐targeted therapy according to their gene aberrations. These results indicate the utility of tumor‐profiling multiplex gene panel testing in a clinical setting in Japan. This study is registered with UMIN Clinical Trials Registry ( UMIN 000011141).

A subset (1% to 5%) of non-small-cell lung carcinomas harbors the EML4-ALK fusion gene. Data from previous studies on the histomorphology of ALK-rearranged lung cancer are inconsistent, and the specific histologic parameters that characterize this subset and how accurately such parameters predict underlying ALK abnormality remain uncertain. To answer these questions, we performed a comprehensive histologic analysis of 54 surgically resected, extensively sampled ALK-rearranged lung carcinomas and compared them with 100 consecutive resections of ALK-wild-type lung cancers. All 54 cases showed at least a focal adenocarcinoma component, and 3 and 2 cases had additional squamous and sarcomatoid differentiation, respectively. Solid or acinar growth pattern, cribriform structure, presence of mucous cells (signet-ring cells or goblet cells), abundant extracellular mucus, lack of lepidic growth, and lack of significant nuclear pleomorphism were more common in ALK-positive cancers. Two recognizable constellations of findings, a solid signet-ring cell pattern and a mucinous cribriform pattern, were present at least focally in the majority (78%) of ALK-positive tumors, but were rare (1%) in ALK-negative tumors. Multivariate analysis showed that a combination of these 2 patterns was the most powerful histologic indicator of ALK rearrangement. Characteristic histologies were present both in primary sites and in metastases. Thus, histologic findings may help to identify cases for ALK testing. However, none of the histologic parameters were completely sensitive or specific to ALK rearrangement, and histomorphology should not replace confirmatory molecular or immunohistochemical studies. ALK-positive cancers commonly showed coexpression of thyroid transcription factor-1 and p63, and its significance is currently unclear.

Solitary fibrous tumor (SFT) is an uncommon fibroblastic neoplasm. Although histologic characteristics and frequent CD34 expression allow for an accurate diagnosis in the majority of SFT cases, a wide histologic spectrum and an occasional unexpected immunophenotype may pose diagnostic challenges. Molecular analyses have discovered that almost all SFTs harbor an NAB2-STAT6 fusion gene, which is considered specific to this tumor type. Recent studies have suggested that STAT6 immunohistochemistry is a reliable surrogate for detection of the fusion gene. Our aim was to validate these findings by examining a large number of SFT cases and a broad array of 30 different types of non-SFT tumors. A total of 49 SFTs with a range of histologic characteristics and 159 benign or malignant tumors that can mimic SFTs were retrieved and stained for STAT6. All 49 SFTs (100%) showed STAT6 expression that was restricted in the nucleus, mostly in a diffuse and strong manner, irrespective of the tumor sites and histologic patterns. The staining was uniform in most cases but was heterogenous in about 20% of the cases in which zonal staining attenuation was observed, likely reflecting variability in fixation or tissue ischemia. In contrast, only 4 non-SFT tumors (2.5%) exhibited weak nuclear STAT6 expression, whereas the remaining 155 cases showed no staining or often weak reactivity in both the cytoplasm and the nucleus. Therefore, nuclear STAT6 immunoreactivity is a highly sensitive and specific marker of SFTs and can be helpful when diagnosis is inconclusive by conventional methods.

Since the 2015 WHO classification was introduced into clinical practice, immunohistochemistry (IHC) has figured prominently in lung cancer diagnosis. In addition to distinction of small cell versus non-small cell carcinoma, patients' treatment of choice is directly linked to histologic subtypes of non-small cell carcinoma, which pertains to IHC results, particularly for poorly differentiated tumors. The use of IHC has improved diagnostic accuracy in the classification of lung carcinoma, but the interpretation of IHC results remains challenging in some instances. Also, pathologists must be aware of many interpretation pitfalls, and the use of IHC should be efficient to spare the tissue for molecular testing. The International Association for the Study of Lung Cancer Pathology Committee received questions on practical application and interpretation of IHC in lung cancer diagnosis. After discussions in several International Association for the Study of Lung Cancer Pathology Committee meetings, the issues and caveats were summarized in terms of 11 key questions covering common and important diagnostic situations in a daily clinical practice with some relevant challenging queries. The questions cover topics such as the best IHC markers for distinguishing NSCLC subtypes, differences in thyroid transcription factor 1 clones, and the utility of IHC in diagnosing uncommon subtypes of lung cancer and distinguishing primary from metastatic tumors. This article provides answers and explanations for the key questions about the use of IHC in diagnosis of lung carcinoma, representing viewpoints of experts in thoracic pathology that should assist the community in the appropriate use of IHC in diagnostic pathology.