Intracranial Mesenchymal Tumor Research Articles

DNA Methylation Profiling Confirms a Challenging Glioblastoma, Atypical Mesenchymal Type Which Mimics Intracranial Mesenchymal Tumor

Abstract Introduction/Objective Brain tumors exhibit distinct DNA methylation patterns that reflect their cellular origin, molecular subtype, and clinical behavior. DNA methylation signatures provide valuable insights into tumor heterogeneity, evolution, and treatment response, guiding personalized therapeutic strategies. Our case, glioblastoma, atypical mesenchymal type confirmed by DNA methylation profile and it reflects the clonal evolution of the glioblastoma metaplasia with minimal glial component which was histologically challenging. Methods/Case Report A 56-year-old gentleman presented with headaches. MRI brain demonstrated a heterogeneous enhancing mass with areas of central necrosis in the left temporal lobe, measuring approximately 49 x 34 mm, with surrounding T2 FLAIR hyperintensity extending into the left basal ganglia, causing compression of the left lateral ventricle and uncal herniation. He underwent left-sided craniotomy for tumor resection. Microscopic examination revealed hypercellular spindle cell neoplasm, forming fascicles. Brisk mitotic activity and geographic necrosis were evident. GFAP highlighted narrow margins of the tumor which could represent the entrapped glial tissue. CD99 stained the tumor cells, Other immunohistochemical stains for spindle cell work up, like S100, EMA, PR STAT6 and desmin were all negative. A diagnosis of intracranial mesenchymal tumor /sarcoma was considered. Methylation profiling results showed class calibrated scores of 0.9741, compatible with Glioblastoma, IDH-wildtype, atypical mesenchymal type with a cytogenetic profile including gain of chromosome 7 (including EGFR) and loss of chromosome 10 (including PTEN), and loss of CDKN2A/B. Results (if a Case Study enter NA) NA Conclusion Although histopathological examination and immunohistochemical study are fundamental in diagnosing brain tumors, the rapid development of cytogenetic and molecular diagnostic modalities has significantly contributed to diagnostic accuracy and the potential for targeted treatment. Particularly, DNA methylation profiling has proven valuable in diagnosing morphologically challenging cases with prognostic value. Eventually, DNA methylation profiling will be adopted as a major cancer diagnostic criterion and will become a standard procedure performed at major academic centers.

OTHR-08. CLINICAL MANAGEMENT OF TWO PEDIATRIC CASES OF INTRACRANIAL MESENCHYMAL TUMORS WITH FET::CREB FUSIONS

Abstract BACKGROUND Intracranial mesenchymal tumors (IMTs) with FET::CREB fusion are a newly described provisional entity lacking standard management options. This group of neoplasms occur in children and young adults, and is molecularly characterized by a FET family gene (most commonly EWSR1, rarely FUS) fused with a CREB family transcription factor (ATF1, CREB1, or CREM). Histologically, the Ki-67 index is typically low (<5%) and only rarely elevated (15-20%). Treatment consists of surgical resection. Cases achieving gross total resection (GTR) are observed without adjuvant therapy, while subtotal resection (STR) is followed by radiation therapy. Regardless of resection status, patients are at risk for local recurrence. METHODS Case report. RESULTS We present two patients with IMTs harboring FET::CREB fusions. Patient 1 is a 12-year-old male with a known left choroid plexus lesion and hydrocephalus, who presented with acute loss of balance, headaches, and emesis. CT head revealed progression of the choroid plexus lesion with intraventricular hemorrhage and worsening hydrocephalus. Following GTR of the tumor, pathology revealed an IMT without high-grade features and a Ki-67 index of 5%. RNA-sequencing revealed an EWSR1::ATF1 fusion. In consideration of GTR and the tumor being low-grade, he is being followed with surveillance scans. Patient 2 is a 14-year-old male who presented with headaches and seizures and was found to have an enhancing left occipital lesion on MRI. Following GTR, pathology revealed an IMT with abundant mitotic figures (15 per 10 high power fields), increased Ki-67 index of 30-40%, and a FUS::CREM fusion. Due to the high-grade histopathology, he was treated with focal proton beam radiotherapy (5400 cGyRBE). An MRI three months post-therapy was negative for tumor recurrence. CONCLUSIONS We describe two adolescents with IMTs harboring FET::CREB fusions and their management, including one with high-grade histology managed with upfront radiation therapy, which has not been previously reported in the literature.

Potential prognostic determinants for FET::CREB fusion-positive intracranial mesenchymal tumor

Intracranial mesenchymal tumor (IMT), FET::CREB fusion-positive is a provisional tumor type in the 2021 WHO classification of central nervous system tumors with limited information available. Herein, we describe five new IMT cases from four females and one male with three harboring an EWSR1::CREM fusion and two featuring an EWSR1::ATF1 fusion. Uniform manifold approximation and projection of DNA methylation array data placed two cases to the methylation class “IMT, subclass B”, one to “meningioma-benign” and one to “meningioma-intermediate”. A literature review identified 74 cases of IMTs (current five cases included) with a median age of 23 years (range 4–79 years) and a slight female predominance (female/male ratio = 1.55). Among the confirmed fusions, 25 (33.8%) featured an EWSR1::ATF1 fusion, 24 (32.4%) EWSR1::CREB1, 23 (31.1%) EWSR1::CREM, one (1.4%) FUS::CREM, and one (1.4%) EWSR1::CREB3L3. Among 66 patients with follow-up information available (median: 17 months; range: 1–158 months), 26 (39.4%) experienced progression/recurrences (median 10.5 months; range 0–120 months). Ultimately, three patients died of disease, all of whom underwent a subtotal resection for an EWSR1::ATF1 fusion-positive tumor. Outcome analysis revealed subtotal resection as an independent factor associated with a significantly shorter progression free survival (PFS; median: 12 months) compared with gross total resection (median: 60 months; p < 0.001). A younger age (< 14 years) was associated with a shorter PFS (median: 9 months) compared with an older age (median: 49 months; p < 0.05). Infratentorial location was associated with a shorter overall survival compared with supratentorial (p < 0.05). In addition, the EWSR1::ATF1 fusion appeared to be associated with a shorter overall survival compared with the other fusions (p < 0.05). In conclusion, IMT is a locally aggressive tumor with a high recurrence rate. Potential risk factors include subtotal resection, younger age, infratentorial location, and possibly EWSR1::ATF1 fusion. Larger case series are needed to better define prognostic determinants in these tumors.

Intracranial mesenchymal tumors with &lt;i&gt;FET–CREB&lt;/i&gt; fusion

Intracranial mesenchymal tumors with rearrangements of the genes of the FET and CREB families were first described in the 2021 World Health Organization classification of tumors of the central nervous system. At the moment, the criteria for the diagnosis and treatment of these tumors have not been unambiguously defined. This article presents two exceptionally rare clinical cases of adolescent patients with IMT with the presence of gene rearrangement of the FET and CREB gene families, who were treated and examined at the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology. The patients’ parents gave consent to the use of their children's data, including photographs, for research purposes and in publications.

Case Report: Remarkable breakthrough: successful treatment of a rare intracranial mesenchymal, FET::CREB fusion-positive tumor treated with patient-tailored multimodal therapy

BackgroundIntracranial mesenchymal tumors are a rare type of neoplasm (0.3% of all soft tissue tumors) characterized by a fusion of a FET family gene (usually EWSR1, rarely FUS) to CREB family genes (CREB1, ATF1, and CREM) with a slow-growing and favorable prognosis. Mesenchymal tumors are most frequently localized in the subcutaneous tissue (typically in the limbs and hands) of young adults and have rarely been diagnosed in the central nervous system. Surgery is the gold standard treatment; adjuvant radiation therapy and chemotherapy with sarcoma-based regimens have been used in rare cases when complete surgical excision was not recommended. In terms of prognosis, these tumors show a tendency for local relapse. The longest patient outcomes reported in the literature are five years.Case descriptionThis case describes a 27-year-old woman with unconventional extracranial metastatic sites of myxoid intracranial mesenchymal tumor FET::CREB fusion-positive and high expression of PD-1 (40%) and PD-L1 (30%). Based on clinical, molecular, and histological characteristics, she underwent various local and systemic therapies, including surgery, proton beam therapy, the use of immune checkpoint inhibitors, and chemotherapy. These treatments led to a complete remission of the disease after eight years from tumor diagnosis.ConclusionsOur case sheds light on the importance of precision medicine and tailored therapy to explore new treatment opportunities for rare or unknown tumor entities.

Mesenchymal and Non-meningothelial Tumors Involving the Central Nervous System

In the World Health Organization Classification of Brain Tumors Fifth Edition, mesenchymal non-meningothelial tumors involving the central nervous system are divided into three major categories: soft tissue tumors, chondro-osseous tumors, and notochordal tumors. Soft tissue tumors are classified into four groups: fibroblastic and myofibroblastic tumors, vascular tumors, skeletal muscle tumors, and tumors of uncertain differentiation. This article will focus on solitary fibrous tumors(SFTs), which are frequently encountered clinically and continue to undergo classification revisions in the 5th edition, and outline the three newly added histological diagnoses. Although SFTs and hemangiopericytomas occur throughout the body, including the central nervous system, nomenclatures have been different between the classifications of "Tumours of Soft Tissue and Bone" and "Tumours of the Central Nervous System." The latest nomenclature is "SFT" in accordance with the nomenclature of bone and soft-tissue tumors. In addition, three new diagnoses, which are intracranial mesenchymal tumor FET-CREB fusion-positive, CIC-rearranged sarcoma, and primary intracranial sarcoma DICER1-mutant, have been defined based on genetic abnormalities in tumors of uncertain differentiation.

Intracranial mesenchymal tumor with (novel) COX14::PTEN rearrangement

Mesenchymal tumors of the central nervous system (CNS) include numerous entities, with different pathological features and biological behavior. Mesenchymal non-meningothelial tumors are rare and comprise neoplasms that are exclusive to the CNS or show peculiar features when occurring in the CNS compared with other sites. Within this group there are three new entities, classified on the basis of specific molecular alterations and included in the 5th edition of the WHO Classification of CNS Tumors: primary intracranial sarcoma; DICER1-mutant; CIC-rearranged sarcoma; intracranial mesenchymal tumor, FET::CREB fusion-positive. These tumors often show variable morphology, making diagnosis very challenging, although the implementation of molecular techniques has led to better characterization and more precise identification of these entities. However, many molecular alterations have yet to be discovered and some recently reported CNS tumors are currently missing an appropriate classification. Herein, we report the case of a 43-year-old man who presented with an intracranial mesenchymal tumor. Histopathological examination showed a wide spectrum of peculiar morphological features and a non-specific immunohistochemical profile. Whole transcriptome sequencing revealed the presence of a novel genetic rearrangement involving COX14 and PTEN genes, which has never been reported before in any other neoplasm. The tumor did not cluster in any defined methylation class of the brain tumor classifier, but resulted in a calibrated score of 0.89 for the methylation class “Sarcoma, MPNST-like”, when analyzed by the sarcoma classifier. Our study is the first to report about this tumor with unique pathological and molecular features, characterized by a novel rearrangement between COX14 and PTEN genes. Other studies are necessary in order to define it as a new entity or as a novel rearrangement involving recently described and incompletely characterized CNS mesenchymal tumors.

Some CNS sarcomas seen: A 22-year series.

Central nervous system (CNS) and spine are seldom impacted by primary or metastatic sarcomas. We reviewed our 22-year experience with metastatic versus primary mesenchymal sarcomas in adults versus pediatric patients, additionally asking how many might today undergo nomenclature changes using CNS World Health Organization, 5th edition criteria. Case identification via text word search of pathology databases from our adult and pediatric referral hospitals, 2000 to August 2022, with exclusion of peripheral nervous system and primary chondro-osseous and notochordal tumors. Demographic, immunohistochemical, fluorescence in situ hybridization (FISH), and fusion results performed at the time of original diagnosis were acquired from reports. 57 cases were identified, with a 16 : 15 primary and 19 : 7 metastatic ratio in adult versus pediatric patients. Ewing sarcoma was the most frequent type (n = 18, 7 adult, 11 pediatric), with a rare primary PEComa, 2 alveolar soft part sarcomas, and metastatic angiosarcoma in the cohort. Only 3 cases, an intracranial sarcoma, DICER-1 mutant formerly diagnosed as rhabdomyosarcoma, an intracranial mesenchymal tumor, FET::CREB fusion-positive formerly diagnosed as angiomatoid fibrous histiocytoma, and a CIC-rearranged sarcoma required nomenclature updating by CNS WHO5 criteria. Few primary or metastatic, adult or pediatric, CNS/spinal sarcomas required nomenclature updates; almost all had been satisfactorily classified at the time of diagnosis, using immunohistochemistry, FISH, or fusion results.

Expanding the spectrum of “mesenchymal” tumors of the central nervous system

In this review, we summarize the clinical, histopathological, and molecular features of central nervous system (CNS) tumors with BCOR internal tandem duplication, intracranial mesenchymal tumor with FET/CREB fusion, CNS CIC-rearranged sarcomas and primary intracranial sarcoma DICER1-mutant, now included in the 2021 WHO classification of CNS tumors. Possible relationships between tumors occurring in the CNS and their systemic counterparts are discussed.

Intracranial mesenchymal tumors with EWSR1-CREB1 fusion-positive: a clinicopathological study of three cases

目的： 探讨原发性颅内间叶性肿瘤伴FET-CREB融合阳性型的临床及影像表现、病理形态学特征及分子遗传特点。 方法： 回顾性分析3例伴有FET-CREB融合阳性的原发性颅内间叶性肿瘤患者的临床病理特征、免疫表型、诊断、治疗及预后，并复习相关文献。 结果： 3例患者年龄分别为31、16、35岁，男性2例，女性1例，发病部位分别为右额部、左额颞部和右侧脑室，影像学均表现为界限清楚的占位性病变。镜下观察：组织学上共同特征表现为肿瘤边界清楚，背景可见多少不等的胶原化及黏液样改变，肿瘤细胞疏密不等，呈条索状或片状分布于黏液性间质中，部分病例可见血管丰富，肿瘤组织围绕血管生长，肿瘤细胞呈梭形、星芒状或上皮样。免疫组织化学染色显示肿瘤细胞均表达结蛋白及CD99，2例表达上皮细胞膜抗原，1例表达间变性淋巴瘤激酶及CD68，1例表达D2-40，Ki-67阳性指数5%~15%。分子表型：二代测序检测出1例EWSR1-CREB1基因融合及2例EWSR1-CREM基因融合。术后随访6~24个月，3例患者状态均良好，无复发及转移。 结论： FET-CREB融合阳性的原发性颅内间叶性肿瘤，诊断时应与影像特征及镜下形态相似的胶质瘤、脑膜瘤、孤立性纤维性肿瘤及其他伴有EWSR1基因融合的软组织肿瘤鉴别。.

An extracranial CNS presentation of the emerging "intracranial" mesenchymal tumor, FET: CREB-fusion positive.

A novel histomolecular tumor, the "intracranial mesenchymal tumor (IMT), FET::CREB fusion-positive", has recently been identified and added to the 2021 World Health Organization Classification of Tumors of the Central Nervous System. One of the essential diagnostic criteria defined in this classification is the intracranial location of the tumor. Herein, we report a spinal case of IMT with a classical EWSR1::CREM fusion. We compare its clinical, histopathological, immunophenotypical, genetic and epigenetic features with those previously described in IMT, FET::CREB fusion-positive. The current case presented histopathological (epithelioid morphology with mucin-rich stroma, and expression of EMA and desmin), radiological (an extraparenchymal lobulated mass without dural tail), genetic (fusion implicating the EWSR1 and CREM genes), and epigenetic (DNA-methylation profiling) similarities to previously reported cases. This case constitutes the third "extracranial" observation of an IMT. Our results added data suggesting that the terminology "IMT, FET::CREB fusion-positive" is provisional and that further series of cases are needed to better characterize them.

LINC-03. A single center retrospective analysis of current therapy and outcome of central nervous system tumors in children of Beijing

OBJECTIVE: To explore the clinical characteristics, therapy and outcome in children with central nervous system (CNS) tumors in Beijing, China. METHODS: Clinical data of 1003 patients with newly diagnosed CNS tumors under the age of 15 years admitted to Beijing Shijitan Hospital between January 2017 and December 2021 were retrospectively analyzed. The diagnoses were confirmed by pathology and/or molecular tests. RESULTS: 34 patients were lost to follow up. Medulloblastoma (n=472), ependymoma (n=79), ETMR (n=59) and pinealoblastoma (n=19) were treated according to HIT-2000/2017, 5-year progression-free survival (PFS) and overall survival (OS) were 76.4 ± 2.3%/ 84.8 ±1.9% in MB, 88.8±3.7% /89.5±3.8% in ependymoma, 49.9±7.6%/59.6±10.7% in ETMR, and 3y-PFS/OS of 11.1±10.5%, 90.0±9.5% in pinealoblastoma. The detailed histology of 59 cases of embryonal tumors included 40 cases of CNS embryonal tumor, 9 neuroblastoma, 7 ETMR, and 3 rare tumors (Intracranial mesenchymal tumor with FET-CREB fusion, CNS high-grade neuroepithelial tumor with BCOR alteration, and Melanotic neuroectodermal tumor of infancy). Among 19 cases of pinealoblastoma, two contain DICER1 mutations. Atypical teratoid/rhabdoid tumors (n=36) were treated by EU-RHAB-Protocol with 3y-PFS/OS of 42.2 ± 9.4 % and 62.8 ± 9.5 %. For low-grade gliomas (n=153, 114 cases of OPG and 39 other non-STR/NTR or progressive cases) under SIOP-LGG 2004, 5y-PFS/OS rates were 77.6±5.2% and 92.4±3.2%; Comparatively, among 63 cases of high-grade gliomas, 19 cases survived with median survival of 52 months, 44 cases died. Choroid plexus cancers (n=13) were treated according to CPT-SIOP-2009 with 5y-PFS /OS of 68.4 ± 13.1 % and 64.8±14.3 %. Among 109 germ cell tumors, 5y-PFS/OS were 93.8±2.8% and 95.5±2.2%, respectively. CONCLUSION: The prognosis of CNS tumors are related to pathology, molecular type and individualized therapy. By international multicenter cooperation and adopting advanced protocols, the survival rates of pediatric CNS tumors can be significantly improved.

Intracranial mesenchymal tumors with FET-CREB fusion are composed of at least two epigenetic subgroups distinct from meningioma and extracranial sarcomas.

‘Intracranial mesenchymal tumor, FET‐CREB fusion‐positive’ occurs primarily in children and young adults and has previously been termed intracranial angiomatoid fibrous histiocytoma (AFH) or intracranial myxoid mesenchymal tumor (IMMT). Here we performed genome‐wide DNA methylation array profiling of 20 primary intracranial mesenchymal tumors with FET‐CREB fusion to further study their ontology. These tumors resolved into two distinct epigenetic subgroups that were both divergent from all other analyzed intracranial neoplasms and soft tissue sarcomas, including meningioma, clear cell sarcoma of soft tissue (CCS), and AFH of extracranial soft tissue. The first subgroup (Group A, 16 tumors) clustered nearest to but independent of solitary fibrous tumor and AFH of extracranial soft tissue, whereas the second epigenetic subgroup (Group B, 4 tumors) clustered nearest to but independent of CCS and also lacked expression of melanocytic markers (HMB45, Melan A, or MITF) characteristic of CCS. Group A tumors most often occurred in adolescence or early adulthood, arose throughout the neuroaxis, and contained mostly EWSR1‐ATF1 and EWSR1‐CREB1 fusions. Group B tumors arose most often in early childhood, were located along the cerebral convexities or spinal cord, and demonstrated an enrichment for tumors with CREM as the fusion partner (either EWSR1‐CREM or FUS‐CREM). Group A tumors more often demonstrated stellate/spindle cell morphology and hemangioma‐like vasculature, whereas Group B tumors more often demonstrated round cell or epithelioid/rhabdoid morphology without hemangioma‐like vasculature, although robust comparison of these clinical and histologic features requires future study. Patients with Group B tumors had inferior progression‐free survival relative to Group A tumors (median 4.5 vs. 49 months, p = 0.001). Together, these findings confirm that intracranial AFH‐like neoplasms and IMMT represent histologic variants of a single tumor type (‘intracranial mesenchymal tumor, FET‐CREB fusion‐positive’) that is distinct from meningioma and extracranial sarcomas. Additionally, epigenomic evaluation may provide important prognostic subtyping for this unique tumor entity.

A novel SMARCA2-CREM fusion: expanding the molecular spectrum of intracranial mesenchymal tumors beyond the FET genes

A novel histomolecular tumor of the central nervous system, the “intracranial mesenchymal tumor (IMT), FET-CREB fusion-positive” has recently been identified in the literature and will be added to the 2021 World Health Organization Classification of Tumors of the Central Nervous System. However, our latest study using DNA-methylation analyses has revealed that intracranial FET-CREB fused tumors do not represent a single molecular tumor entity. Among them, the main subgroup presented classical features of angiomatoid fibrous histiocytoma, having ultrastructural features of arachnoidal cells, for. Another tumor type with clear cell component and histopathological signs of aggressivity clustered in close vicinity with clear cell sarcoma of soft tissue. Herein, we report one case of IMT with a novel SMARCA2-CREM fusion which has until now never been described in soft tissue or the central nervous system. We compare its clinical, histopathological, immunophenotypic, genetic and epigenetic features with those previously described in IMT, FET-CREB fusion-positive. Interestingly, the current case did not cluster with IMT, FET-CREB fusion-positive but rather presented histopathological (clear cell morphology with signs of malignancy), clinical (with a dismal course with several recurrences, metastases and finally the patient’s death), genetic (fusion implicating the CREM gene), and epigenetic (DNA-methylation profiling) similarities with our previously reported clear cell sarcoma-like tumor of the central nervous system. Our results added data suggesting that different clinical and histomolecular tumor subtypes or grades seem to be included within the terminology “IMT, FET-CREB fusion-positive”, and that further series of cases are needed to better characterize them.

An integrative histopathological and epigenetic characterization of primary intracranial mesenchymal tumors, FET:CREB‐fused broadening the spectrum of tumor entities in comparison with their soft tissue counterparts

FET:CREB fusions have been described in a variety of tumors from various phenotypes. Recently, these fusion transcripts were reported in intracranial tumors, variably named intracranial mesenchymal myxoid tumors or angiomatoid fibrous histiocytomas. Controversy remains concerning the terminology for these tumors. Here, we report 11 cases of central nervous system mesenchymal tumors with proven FET:CREB fusion. Most DNA methylation profiles were not classifiable using the Heidelberg Brain Tumor or Sarcoma Classifier (v11b4/v12.2). However, by using unsupervised t‐SNE and hierarchical clustering analyses, six of the cases constituted a distinct cluster. The remaining four tumors showed no obvious relation to any of the other referenced classes but were close to the clusters of extra‐CNS angiomatoid fibrous histiocytomas (n = 1), clear cell sarcomas (n = 1), or solitary fibrous tumors (n = 2). Our findings confirm that intracranial FET:CREB‐fused tumors do not represent a single molecular tumor entity, although most samples clustered close to each other, indicating the existence of a distinct epigenetic group that could potentially be partially masked by the low number of cases included. Further analyses are needed to characterize intracranial FET:CREB fused‐defined tumors in more detail.

Intracranial mesenchymal tumor with FET‐CREB fusion—A unifying diagnosis for the spectrum of intracranial myxoid mesenchymal tumors and angiomatoid fibrous histiocytoma‐like neoplasms

Intracranial mesenchymal tumors with FET‐CREB fusions are a recently described group of neoplasms in children and young adults characterized by fusion of a FET family gene (usually EWSR1, but rarely FUS) to a CREB family transcription factor (ATF1, CREB1, or CREM), and have been variously termed intracranial angiomatoid fibrous histiocytoma or intracranial myxoid mesenchymal tumor. The clinical outcomes, histologic features, and genomic landscape are not well defined. Here, we studied 20 patients with intracranial mesenchymal tumors proven to harbor FET‐CREB fusion by next‐generation sequencing (NGS). The 16 female and four male patients had a median age of 14 years (range 4–70). Tumors were uniformly extra‐axial or intraventricular and located at the cerebral convexities (n = 7), falx (2), lateral ventricles (4), tentorium (2), cerebellopontine angle (4), and spinal cord (1). NGS demonstrated that eight tumors harbored EWSR1‐ATF1 fusion, seven had EWSR1‐CREB1, four had EWSR1‐CREM, and one had FUS‐CREM. Tumors were uniformly well circumscribed and typically contrast enhancing with solid and cystic growth. Tumors with EWSR1‐CREB1 fusions more often featured stellate/spindle cell morphology, mucin‐rich stroma, and hemangioma‐like vasculature compared to tumors with EWSR1‐ATF1 fusions that most often featured sheets of epithelioid cells with mucin‐poor collagenous stroma. These tumors demonstrated polyphenotypic immunoprofiles with frequent positivity for desmin, EMA, CD99, MUC4, and synaptophysin, but absence of SSTR2A, myogenin, and HMB45 expression. There was a propensity for local recurrence with a median progression‐free survival of 12 months and a median overall survival of greater than 60 months, with three patients succumbing to disease (all with EWSR1‐ATF1 fusions). In combination with prior case series, this study provides further insight into intracranial mesenchymal tumors with FET‐CREB fusion, which represent a distinct group of CNS tumors encompassing both intracranial myxoid mesenchymal tumor and angiomatoid fibrous histiocytoma‐like neoplasms.

A rare case of metastatic solitary fibrous tumor of the pancreas manifesting as a cystic neoplasm: a case report

BackgroundSolitary fibrous tumor (SFT) is a rare mesenchymal tumor that typically arises from the pleura. Although it may appear in other organs, it rarely develops in the pancreas. We report herein a rare case of metastatic SFT of the pancreas originating from an intracranial tumor and subsequently identified as a cystic neoplasm of the pancreas.Case presentationA 58-year-old woman with a past medical history of brain tumor visited the hospital for further investigation of a cystic tumor in the pancreas tail. Abdominal imaging showed a heterogeneously enhancing mass that was initially suspected as a neuroendocrine neoplasm, solid pseudopapillary neoplasm, or mucinous cystic neoplasm of the pancreas. Distal pancreatectomy was performed without any intraoperative and postoperative complications. Pathological findings confirmed a diagnosis of malignant SFT of the pancreas with hyperproliferative potential. A histopathological review of her brain tumor revealed that the pancreatic tumor was derived from her brain lesion. The patient developed recurrent brain disease 4 years after the pancreatectomy, but no recurrence has been observed in the abdominal cavity.ConclusionsSFT should be considered in the differential diagnosis of untypical hypervascular pancreatic mass, particularly in patients with a history of an intrathoracic or intracranial mesenchymal tumor. Immunohistochemical analysis is crucial in detecting this tumor entity. Hyperproliferative status indicates a malignant disease and requires careful postoperative observation.

Primary Intracranial Leiomyosarcoma: Report of a Case and Review of the Literature

A 26-year old man presented with a 3-month history of a progressively enlarging palpable parieto-occipital mass. A CT scan indicated the lesion arose from the dura with bony destruction. A stealth assisted craniotomy was performed with the provisional diagnosis of osteoblastic meningioma. Further histopathologic analysis of the intracranial mass was consistent with leiomyosarcoma. Staging evaluation, including CT and PET scans, demonstrated no other sites of disease. Despite complete surgical resection and radiotherapy to the resection site, the disease recurred locally and systematically 5 months later. Primary intracranial mesenchymal tumors are rare and few cases have been previously reported. Outcomes have been universally poor and current therapeutic approaches appear to have only limited benefit.