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Abstract Background Chondrosarcoma (Chs) is the third most frequent primary malignant tumour of bone and can be primary or secondary, the latter results mainly from the malignant transformation of a benign pre-existing tumour. Methods All the cases diagnosed as Chs (primary tumours, recurrences and/or metastasis and xenotransplanted Chs) from the files of our Department were collected. Only cases with paraffin blocks available were selected (Total 32 cases). Six Tissue Microarrays (TMAs) were performed and all the cases and biopsies were distributed into the following groups: a) only paraffin block available from primary and/or metastatic tumours (3 TMAs), b) paraffin block available from primary and/or metastatic tumours as well as from the corresponding Nude mice xenotransplant (2 TMAs), c) only paraffin block available from xenotransplanted Chs (1 TMA). A reclassification of all the cases was performed; in addition, conventional hematoxylin-eosin as well as immunohistochemistry staining (S100, SOX-9, Ki-67, BCL-2, p53, p16, CK, CD99, Survivin and Caveolin) was analyzed in all the TMA. Results The distribution of the cases according to the histopathological pattern and the location of tumours were as follows: fourteen Grade I Chs (all primaries), two primary Grade II Chs, ten Grade III Chs (all primaries), five dedifferentiated Chs (four primaries and one primary with metastasis), and two Chs from cell cultures (Ch grade III). One recurrent extraskeletal myxoid Chs was included as a control in the TMA. Although there was heterogeneity in immunohistochemistry results of the different material analyzed, S100, SOX-9, Caveolin and Survivin were more expressed. The number of passages in xenotransplants fluctuated between 1 and 13. Curiously, in Grade I Chs, these implanted tumours hardly grew, and the number of passages did not exceed one. Conclusion The study of Chs by means of TMA techniques is very important because it will improve the assessment of different antibodies applied in the immunohistochemical assays. Xenotransplanted tumours in TMA improve knowledge concerning the variability in the morphological pattern shown by these tumours during the evolution in nudes.

Abstract Background Chondrosarcoma is the second most common primary sarcoma of bone. High-grade conventional chondrosarcoma and dedifferentiated chondrosarcoma have a poor outcome. In pre-clinical research aiming at the identification of novel treatment targets, the need for representative cell lines and model systems is high, but availability is scarce. Methods We developed and characterized three cell lines, derived from conventional grade III chondrosarcoma (L835), and dedifferentiated chondrosarcoma (L2975 and L3252) of bone. Proliferation and migration were studied and we used COBRA-FISH and array-CGH for karyotyping and genotyping. Immunohistochemistry for p16 and p53 was performed as well as TP53 and IDH mutation analysis. Cells were injected into nude mice to establish their tumorigenic potential. Results We show that the three cell lines have distinct migrative properties, L2975 had the highest migration rate and showed tumorigenic potential in mice. All cell lines showed chromosomal rearrangements with complex karyotypes and genotypic aberrations were conserved throughout late passaging of the cell lines. All cell lines showed loss of CDKN2A, while TP53 was wild type for exons 5–8. L835 has an IDH1 R132C mutation, L2975 an IDH2 R172W mutation and L3252 is IDH wild type. Conclusions Based on the stable culturing properties of these cell lines and their genotypic profile resembling the original tumors, these cell lines should provide useful functional models to further characterize chondrosarcoma and to evaluate new treatment strategies.

Abstract Background Xenografts have been shown to provide a suitable source of tumor tissue for molecular analysis in the absence of primary tumor material. We utilized ES xenograft series for integrated microarray analyses to identify novel biomarkers. Method Microarray technology (array comparative genomic hybridization (aCGH) and micro RNA arrays) was used to screen and identify copy number changes and differentially expressed miRNAs of 34 and 14 passages, respectively. Incubated cells used for xenografting (Passage 0) were considered to represent the primary tumor. Four important differentially expressed miRNAs (miR-31, miR-31*, miR-145, miR-106) were selected for further validation by real time polymerase chain reaction (RT-PCR). Integrated analysis of aCGH and miRNA data was performed on 14 xenograft passages by bioinformatic methods. Results The most frequent losses and gains of DNA copy number were detected at 9p21.3, 16q and at 8, 15, 17q21.32-qter, 1q21.1-qter, respectively. The presence of these alterations was consistent in all tumor passages. aCGH profiles of xenograft passages of each series resembled their corresponding primary tumors (passage 0). MiR-21, miR-31, miR-31*, miR-106b, miR-145, miR-150*, miR-371-5p, miR-557 and miR-598 showed recurrently altered expression. These miRNAS were predicted to regulate many ES-associated genes, such as genes of the IGF1 pathway, EWSR1, FLI1 and their fusion gene (EWS-FLI1). Twenty differentially expressed miRNAs were pinpointed in regions carrying altered copy numbers. Conclusion In the present study, ES xenografts were successfully applied for integrated microarray analyses. Our findings showed expression changes of miRNAs that were predicted to regulate many ES associated genes, such as IGF1 pathway genes, FLI1, EWSR1, and the EWS-FLI1 fusion genes.

Abstract Background Conventional high-grade osteosarcoma is a primary malignant bone tumor, which is most prevalent in adolescence. Survival rates of osteosarcoma patients have not improved significantly in the last 25 years. Aiming to increase this survival rate, a variety of model systems are used to study osteosarcomagenesis and to test new therapeutic agents. Such model systems are typically generated from an osteosarcoma primary tumor, but undergo many changes due to culturing or interactions with a different host species, which may result in differences in gene expression between primary tumor cells, and tumor cells from the model system. We aimed to investigate whether gene expression profiles of osteosarcoma cell lines and xenografts are still comparable to those of the primary tumor. Methods We performed genome-wide mRNA expression profiling on osteosarcoma biopsies (n = 76), cell lines (n = 13), and xenografts (n = 18). Osteosarcoma can be subdivided into several histological subtypes, of which osteoblastic, chondroblastic, and fibroblastic osteosarcoma are the most frequent ones. Using nearest shrunken centroids classification, we generated an expression signature that can predict the histological subtype of osteosarcoma biopsies. Results The expression signature, which consisted of 24 probes encoding for 22 genes, predicted the histological subtype of osteosarcoma biopsies with a misclassification error of 15%. Histological subtypes of the two osteosarcoma model systems, i.e. osteosarcoma cell lines and xenografts, were predicted with similar misclassification error rates (15% and 11%, respectively). Conclusions Based on the preservation of mRNA expression profiles that are characteristic for the histological subtype we propose that these model systems are representative for the primary tumor from which they are derived.

The clinical, radiological, and histopathological features of chondromyxoid fibroma can sometimes resemble those of other benign or malignant tumors. Recently, recurrent GRM1 rearrangements have been identified in chondromyxoid fibroma, and GRM1 positivity by immunohistochemistry has emerged as a dependable surrogate marker for this molecular alteration. Phosphaturic mesenchymal tumor is a rare tumor that often exhibits overexpression of fibroblastic growth factor 23 (FGF23) through various mechanisms. In this report, we present a case of GRM1 -rearranged chondromyxoid fibroma that also exhibited FGF23 expression via in situ hybridization, posing significant diagnostic challenges during workup of the initial core biopsy. We hope that this case can serve as an educational resource, shedding light on a rare diagnostic pitfall. [ABSTRACT FROM AUTHOR]

Simple Summary: Solitary fibrous tumors (SFTs) are tumors that can vary greatly in how they behave, with some being harmless while others become aggressive and life-threatening. This study evaluated 52 fusion-confirmed SFTs with clinical follow-up. The aim was to analyze the immune intratumoral infiltrate and correlate the presence of specific immune cells and risk stratification systems to see if the presence or absence of certain cells could help predict how the tumor will behave or correlate with other clinicopathologic characteristics. The research found that, while certain immune cells were associated with specific tumor features with prognostic significance, these immune cells did not reliably predict the tumor's overall risk level. This suggests that the immune environment within SFTs is complex and may not be useful on its own for determining the tumor progression risk. Nonetheless, the presented results give an insight into the relationship between immune tumor cells and histologic characteristics such as necrosis, proliferation index, and neoplastic cell morphology. Background and objectives: Solitary fibrous tumors (SFTs) are morphologically heterogeneous tumors characterized by the NAB2::STAT6 gene fusion. Clinical outcomes may vary widely, and while most cases have favorable outcomes, some can progress to aggressive disease, manifesting as recurrence and metastasis, and ultimately resulting in patient death. Herein, we analyze the immunological tumor microenvironment (ITME) of SFTs, aiming to determine its prognostic value and correlation with established risk stratification systems (RSSs). Methods: A retrospective observational multicenter study of 52 fusion-confirmed SFTs with clinical follow-up data. Immunohistochemical analysis including CD163, CD68, CD3, CD8, CD20, PDL-1, PD-1, and LAG1 were evaluated in tissue microarrays, using an analog scale with scores ranging from 0 to 3 (0 = ≤9, 1 = 10–49, 2 = 50–99, and 3 = >100 positive cells per 10 high-power fields). The expression of these markers was correlated with clinical outcomes, morphological characteristics previously evaluated in whole slide tissue sections (hypercellularity/hypocellularity, round–oval or spindle dominant constituent cell (DCC) morphology, and necrosis), Ki67, overall survival, and RSS. Results: Only one of the fifty-two cases studied showed progression. In the multivariate analysis, neither the presence nor absence of immune cells (B-lymphocytes, T-lymphocytes, and macrophages) showed any association with the assessed RSSs (Demicco, Sugita, G-score, and Huang). Interestingly, the case that showed progression had high immune infiltrate with expression of CD68, CD163, CD8, and CD20 markers (score of 3). Round–oval cell morphology was associated with the presence of higher levels of CD163 macrophages. Lastly, the scant presence of CD20+ lymphocytes correlated with less necrosis, and cases with higher PDL-1 expression correlated with increased Ki67 values. All cases were negative for LAG-1 and PD-1. Conclusions: SFT ITME components correlated with independent variables with prognostic significance. Nevertheless, ITME did not correlate with RSS scores. [ABSTRACT FROM AUTHOR]

Primary rectal adenocarcinoma with extensive choriocarcinomatous differentiation is a rare neoplasm, with only sporadic cases reported worldwide. The prognosis is typically poor, and no standard therapy has been established for this tumor. We report a case of a 63-year-old woman who presented with lower abdominal and pelvic discomfort, as well as rectal bleeding. Endoscopy revealed a rectal tumor. She was diagnosed with primary rectal adenocarcinoma with extensive choriocarcinomatous differentiation, accompanied by liver metastasis and peritoneal carcinomatosis. The immunohistochemical profile demonstrated strong and diffuse positivity for keratin (AE1/AE3), beta-human chorionic gonadotropin (β-HCG), p53, MYC, p16, and Ki-67. Molecular analysis indicated mutations in KRAS, TP53, and PI3KCA. Despite the tumor's profile, the serum β-HCG level was not elevated. A chemotherapy regimen for metastatic colorectal adenocarcinoma was initiated, but there was a poor response, with rapid tumor progression. The patient survived for only 5 months postdiagnosis. We discuss the histopathological, immunohistochemical, and molecular findings, emphasizing their relevance to the differential diagnosis of neoplasms with choriocarcinomatous differentiation. [ABSTRACT FROM AUTHOR]

Synovial sarcoma (SS) is a rare soft-tissue tumor characterized by a monomorphic blue spindle cell histology and variable epithelial differentiation. Morphologically, SSs may be confused with other sarcomas. Systemic treatment is more effective for patients with high-risk SSs, patients with advanced disease, and younger patients. However, further studies are required to find new prognostic biomarkers. Herein, we describe the morphological, molecular, and clinical findings, using a wide immunohistochemical panel, of a series of SS cases. We studied 52 cases confirmed as SSs by morphological diagnosis and/or molecular studies. Clinical data (gender, age, tumor size, tumor location, resection margins, adjuvant treatment, recurrences, metastasis, and survival) were also retrieved for each patient. All the available H&E slides were examined by four pathologists. Three tissue microarrays (TMAs) were constructed for each of the tumors, and a wide immunohistochemical panel was performed. For time-to-event variables, survival analysis was performed using Kaplan–Meier curves and log-rank testing, or Cox regression. Statistical significance was considered at p < 0.05. The mean age of our patients was 40.33, and the median was 40.5 years. We found a predominance of males versus females (1.7:1). The most frequent morphological subtype was monophasic. TRPS1, SS18-SSX, and SSX-C-terminus were positive in 96% of cases. GLI1 expression was strong in six and focal (cytoplasmic) in twenty patients. Moreover, BCOR was expressed in more than half of SSs. Positive expression of both proteins, BCOR and GLI1, was correlated with a worse prognosis. Multivariate analysis was also performed, but only BCOR expression appeared to be significant. The combination of GLI1 and BCOR antibodies can be used to group SSs into three risk groups (low, intermediate, and high risk). We hypothesize that these findings could identify which patients would benefit from receiving adjuvant treatment and which would not. Moreover, these markers could represent therapeutic targets in advanced stages. However, further, larger series of SSs and molecular studies are necessary to corroborate our present findings. [ABSTRACT FROM AUTHOR]

Simple Summary: Current clinical practice guidelines support additional locoregional surgery after local resection of early colorectal cancer when one or more of the following risk factors are present: poor differentiation grade, lymphovascular invasion, deep submucosal invasion, moderate or high tumor budding, and deep margin involvement. The absence of all these risk criteria selects a subgroup of patients with very good prognosis that can safely avoid additional surgery. However, lymph node metastases are only identified in 10–20% of patients who ultimately undergo additional surgery, so that 80–90% of the surgeries turn out to be unnecessary. In this investigation, we find that indicating additional surgery in early colorectal cancer only when either moderate or high tumor budding, poorly differentiated clusters, or lymphovascular invasion are present could reduce unnecessary surgeries by 40–45% without significantly increasing the proportion of patients with lymph node metastases who are not offered additional surgery. Background: The low positive predictive value for lymph node metastases (LNM) of common practice risk criteria (CPRC) in T1 colorectal carcinoma (CRC) leads to manyunnecessary additional surgeries following local resection. This study aimed to identify criteria that may improve on the CPRC. Methods: Logistic regression analysis was performed to determine the association of diverse variables with LNM or 'poor outcome' (LNM and/or distant metastases and/or recurrence) in a single center T1 CRC cohort. The diagnostic capacity of the set of variables obtained was compared with that of the CPRC. Results: The study comprised 161 cases. Poorly differentiated clusters (PDC) and tumor budding grade > 1 (TB > 1) were the only independent variables associated with LNM. The area under the curve (AUC) for these criteria was 0.808 (CI 95% 0.717–0.880) compared to 0.582 (CI 95% 0.479–0.680) for CPRC. TB > 1 and lymphovascular invasion (LVI) were independently associated with 'poor outcome', with an AUC of 0.801 (CI 95% 0.731–0.859), while the AUC for CPRC was 0.691 (CI 95% 0.603–0.752). TB > 1, combined either with PDC or LVI, would reduce false positives between 41.5% and 45% without significantly increasing false negatives. Conclusions: Indicating additional surgery in T1 CRC only when either TB > 1, PDC, or LVI are present could reduce unnecessary surgeries significantly. [ABSTRACT FROM AUTHOR]

The Ewing sarcoma family of tumors (EFT) is a group of highly malignant small round blue cell tumors occurring in children and young adults. We report here the largest genomic survey to date of 101 EFT (65 tumors and 36 cell lines). Using a combination of whole genome sequencing and targeted sequencing approaches, we discover that EFT has a very low mutational burden (0.15 mutations/Mb) but frequent deleterious mutations in the cohesin complex subunit STAG2 (21.5% tumors, 44.4% cell lines), homozygous deletion of CDKN2A (13.8% and 50%) and mutations of TP53 (6.2% and 71.9%). We additionally note an increased prevalence of the BRCA2 K3326X polymorphism in EFT patient samples (7.3%) compared to population data (OR 7.1, p = 0.006). Using whole transcriptome sequencing, we find that 11% of tumors pathologically diagnosed as EFT lack a typical EWSR1 fusion oncogene and that these tumors do not have a characteristic Ewing sarcoma gene expression signature. We identify samples harboring novel fusion genes including FUS-NCATc2 and CIC-FOXO4 that may represent distinct small round blue cell tumor variants. In an independent EFT tissue microarray cohort, we show that STAG2 loss as detected by immunohistochemistry may be associated with more advanced disease (p = 0.15) and a modest decrease in overall survival (p = 0.10). These results significantly advance our understanding of the genomic and molecular underpinnings of Ewing sarcoma and provide a foundation towards further efforts to improve diagnosis, prognosis, and precision therapeutics testing.

Calcified chondroid mesenchymal neoplasm is a recently recognized bone and soft tissue entity primarily found in the extremities and the temporomandibular joint. This neoplasm is typically driven by the fusion of the FN1 gene with a kinase. In this case report, we provide a detailed account of a rare superficial calcified chondroid mesenchymal neoplasm located on the left big toe, characterized by an FN1::FGFR2 fusion. The tumor exhibited a peripheral collarette and consisted of large intradermal histiocytoid to epithelioid cells with no mitotic activity. These cells displayed fine chromatin and abundant pale eosinophilic cytoplasm, forming a swirling syncytium. They were interspersed with localized areas of glassy chondromyxoid matrix containing randomly mineralized calcific material and isolated osteoclast‐like giant cells. RNA sequencing confirmed the presence of an FN1 (exon 29)::FGFR2 (exon 7) gene fusion. Our report emphasizes the importance for dermatopathologists to consider this entity when evaluating superficial lesions displaying mesenchymal, chondroid, and calcified attributes. [ABSTRACT FROM AUTHOR]