A novel WWTR1-CAMTA1 gene fusion is a consistent abnormality in epithelioid hemangioendothelioma of different anatomic sites

A case of hepatic epithelioid hemangioendothelioma with features resembling those of acute-onset autoimmune hepatitis that was undiagnosed before liver transplantation

Hepatic epithelioid hemangioendothelioma (HEHE), which is extremely rare, is considered to have a malignant grade between that of hepatic hemangioma and that of hepatic hemangiosarcoma; however, some cases progress so quickly that they present with portal hypertension. We report the case of a woman with findings similar to those of acute-onset autoimmune hepatitis (AIH) that was not diagnosed before liver transplantation. The patient presented with jaundice and ascites. A hematological examination revealed negative tumor markers, high IgG levels, and negative hepatitis virus markers. Computed tomography findings of the liver showed map-like signs characteristic of acute-onset AIH. Despite some response, immunosuppressive drugs such as prednisolone, cyclosporine, and mycophenolate mofetil did not improve liver failure, and she underwent liver transplantation after 200 days of treatment. The explanted liver exhibited white areas that extended in a map-like manner and were occupied by fibrous stroma. Tumors with WWTR1-CAMTA1 gene fusion were recognized and diagnosed as HEHE. Although a histological examination is essential, a percutaneous liver biopsy could not be performed preoperatively because of the presence of ascites. Furthermore, the rarity of the disease, similarity of imaging findings with non-neoplastic patterns, and serological findings made it difficult to differentiate this case from acute-onset autoimmune hepatitis.

Cutaneous Hemangioma With Epithelioid Features Harboring TPM3/4::ALK Fusions : A Distinct Entity or a Molecular Variant of Epithelioid Hemangioma?

Vascular neoplasms with epithelioid cytomorphology encompass a wide spectrum of benign and malignant lesions, including epithelioid hemangioma (EH), cutaneous epithelioid angiomatous nodule (CEAN), epithelioid hemangioendothelioma (EHE), and epithelioid angiosarcoma (EAS). Recently, the first case of a cutaneous hemangioma with epithelioid features harboring a TPM3::ALK fusion was reported. Herein, we report 4 additional cases, including 1 case with an alternate TPM4::ALK fusion, and expand on the clinicopathologic and molecular genetic features of these unusual vascular lesions. Including the previously reported case, 5 tumors occurred in 4 male and 1 female patients with a median age of 14 years (range: 2 to 38 y) and involved the shoulder region (2), the lower extremity (1), trunk (1), and head and neck (1). Clinical follow-up (3 patients; 60%) showed no evidence of disease at the last follow-up (median: 5 mo; range: 1 to 16 mo). Histologically, all tumors showed highly similar morphologic features, including an epidermal collarette, well-formed vascular channels composed of epithelioid endothelial cells with intracytoplasmic vacuoles, and admixed inflammatory cells. Immunohistochemically, all tumors were positive for vascular markers such as ERG and CD31, along with strong and diffuse cytoplasmic expression of ALK. RNA sequencing revealed recurrent TPM3 exon 8 :: ALK exon 20 (4) and TPM4 exon 7 :: ALK exon 20 fusions (1). We conclude that cutaneous hemangiomas with epithelioid features harboring TPM3/4::ALK fusions show consistent morphologic, immunophenotypic, and molecular genetic features. It remains to be determined whether this neoplasm represents a distinct entity or a molecular variant of epithelioid hemangioma.

Epithelioid Hemangioendothelioma: Treatment Landscape and Innovations for an Ultra-Rare Sarcoma

OPINION STATEMENT

Epithelioid hemangioendothelioma (EHE) is an ultra-rare sarcoma with a paucity of data on best practices for management. Pathogenic translocations involving the YAP or TAZ genes lead to constitutive activation of TEAD and TEAD-associated pathways. As our understanding of the molecular drivers of EHE has advanced, investigational treatment strategies have shifted away from cytotoxic chemotherapy toward more targeted approaches. This review focuses on the historical context and evolving landscape of systemic therapies for patients with EHE. For newly diagnosed patients, we recommend consultation at a high-volume sarcoma center whenever possible. If the disease is localized and resectable, surgical excision by a sarcoma-focused surgical oncologist is preferred. When the disease is unresectable, we first assess for disease progression to determine whether active surveillance is appropriate. Some patients may experience indolent, asymptomatic disease for years-or even decades-without requiring intervention. In patients with progressive or symptomatic unresectable disease, systemic therapy is warranted. Setting realistic expectations about the goals of treatment is essential, as no current systemic therapies reliably reduce tumor burden. However, molecular profiling and ongoing correlative studies from clinical trials may soon identify more effective therapeutic targets. For this reason, we encourage referral to centers that routinely perform molecular profiling and offer clinical trials with eligibility criteria for EHE, even to be considered as a first-line approach. Outside of a clinical trial, cytotoxic chemotherapy remains the frontline standard of care for patients who require systemic treatment. Importantly, treatment decisions must incorporate patient preferences and recognition that symptomatic improvement alone can be a meaningful outcome for preserving quality of life.

What is New in Pediatric Hepatic Neoplasms

The goal of this review is to provide a practical update on hepatic lesions affecting the pediatric population and is not meant to be an exhaustive summary of each entity. Hepatoblastoma is purposely not discussed as recent comprehensive reviews on this topic are available; instead, a discussion on rhabdoid tumor and the evolving concept of small cell undifferentiated hepatoblastoma and blastemal hepatoblastoma is included.

Liver transplantation as a treatment for cancer: comprehensive review

BACKGROUND

Liver transplantation for cancer indications has gained momentum in recent years. This review is intended to optimize the care setting of liver transplant candidates by highlighting current indications, technical aspects and barriers with available solutions to facilitate the guidance of available strategies for healthcare professionals in specialized centres.

METHODS

A review of the most recent relevant literature was conducted for all the cancer indications of liver transplantation including colorectal cancer liver metastases, hilar cholangiocarcinoma, intrahepatic cholangiocarcinoma, neuroendocrine tumours, hepatocellular carcinoma and hepatic epitheloid haemangioendothelioma.

RESULTS

Transplant benefit from the best available evidence, including SECA I, SECA II, TRANSMET studies for colorectal liver metastases, various preoperative protocols for cholangiocarcinoma patients, standard, extended selection criteria for hepatocellular carcinoma and neuroendocrine tumours, are discussed. Innovative approaches to deal with organ shortages, including machine-perfused deceased grafts, living donor liver transplantation and RAPID procedures, are also explored.

CONCLUSION

Cancer indications for liver transplantation are here to stay, and the selection criteria among all cancer groups are likely to evolve further with improved prognostication of tumour biology using adjuncts such as radiomics, cancer genomics, and circulating DNA and RNA status. International prospective registry-based studies could overcome the limitations of smaller patient cohorts and lack of level 1 evidence.

First-line pazopanib in patients with metastatic epithelioid hemangioendothelioma: a retrospective single-center analysis

PURPOSE

Epithelioid hemangioendothelioma (EHE) represents an ultra-rare, translocated vascular sarcoma with a heterogeneous course of disease. The optimal systemic treatment for patients with advanced EHE remains unclear. We sought to evaluate the value of pazopanib (PAZ) as a first-line treatment in metastatic EHE.

METHODS

Thirteen patients with metastatic EHE and PAZ as a first-line treatment at our institution between 2012 und 2023 were reviewed and analyzed with regard to clinical outcomes.

RESULTS

At a median follow-up of 51.4 months, the median progression-free survival (PFS) and overall survival (OS) were 35.1 and 53.8 months, respectively. In patients with documented prior tumor progression (n = 10), the median PFS and OS were 12.6 and 105 months, respectively. In patients with serosal effusion/ systemic symptoms (n = 4), the median PFS and OS were 6.1 and 10.3 months. The clinical benefit rate of the overall cohort was 62% with no complete or partial responses. Two of four patients experienced a reduction of symptoms (pain and ascites reduction/hemoptysis, respectively) under treatment with PAZ. Toxicity was mainly gastrointestinal and manageable with dose reductions. Permanent treatment interruption due to toxicity was necessary in one patient.

CONCLUSION

This is the first study to systematically report survival outcomes for PAZ as a first-line treatment in patients with metastatic EHE. PAZ is active and safe in patients with metastatic EHE and may be considered as an alternative to sirolimus for specific patient subgroups. RECIST criteria should be questioned for evaluation of treatment response in EHE.

EHE cell cultures: a platform for mechanistic and therapeutic investigation

Epithelioid hemangioendothelioma (EHE) is a difficult to treat vascular sarcoma defined by TAZ- CAMTA1 or YAP-TFE3 fusion proteins. Human cell lines needed to further understand the pathogenesis of EHE have been lacking. Herein, we describe a method to generate EHE extended primary cell cultures. An integrated multi -omic and functional approach was used to characterize these cultures. The cell cultures, relatively homogenous by single cell RNA-Seq, demonstrated established characteristics of EHE including increased proliferation, anchorage independent growth, as well as the overall gene expression profile and secondary genetic alterations seen in EHE. Whole genome sequencing (WGS) identified links to epigenetic modifying complexes, metabolic processes, and pointed to the importance of the extracellular matrix (ECM) in these tumors. Bulk RNA-Seq demonstrated upregulation of pathways including PI3K-Akt signaling, ECM/ECM receptor interaction, and the Hippo signaling pathway. Development of these extended primary cell cultures allowed for single-cell profiling which demonstrated different cell compartments within the cultures. Furthermore, the cultures served as a therapeutic platform to test the efficacy of TEAD inhibitors in vitro . Overall, the development of EHE primary cell cultures will aid in the mechanistic understanding of this sarcoma and serve as a model system to test new therapeutic approaches.

The Hippo pathway: Organ size control and beyond

The Hippo signaling pathway is a highly conserved signaling network for controlling organ size, tissue homeostasis, and regeneration. It integrates a wide range of intracellular and extracellular signals, such as cellular energy status, cell density, hormonal signals, and mechanical cues, to modulate the activity of YAP/TAZ transcriptional coactivators. A key aspect of Hippo pathway regulation involves its spatial organization at the plasma membrane, where upstream regulators localize to specific membrane subdomains to regulate the assembly and activation of the pathway components. This spatial organization is critical for the precise control of Hippo signaling, as it dictates the dynamic interactions between pathway components and their regulators. Recent studies have also uncovered the role of biomolecular condensation in regulating Hippo signaling, adding complexity to its control mechanisms. Dysregulation of the Hippo pathway is implicated in various pathological conditions, particularly cancer, where alterations in YAP/TAZ activity contribute to tumorigenesis and drug resistance. Therapeutic strategies targeting the Hippo pathway have shown promise in both cancer treatment, by inhibiting YAP/TAZ signaling, and regenerative medicine, by enhancing YAP/TAZ activity to promote tissue repair. The development of small molecule inhibitors targeting the YAP-TEAD interaction and other upstream regulators offers new avenues for therapeutic intervention. SIGNIFICANCE STATEMENT: The Hippo signaling pathway is a key regulator of organ size, tissue homeostasis, and regeneration, with its dysregulation linked to diseases such as cancer. Understanding this pathway opens new possibilities for therapeutic approaches in regenerative medicine and oncology, with the potential to translate basic research into improved clinical outcomes.

Clinician's primer for soft tissue sarcomas: Nuances of histologic subtypes

Soft tissue sarcomas are a rare group of mesenchymal malignancies, with greater than 100 histologic subtypes. Advancements in understanding these subtypes has enabled histology-tailored management. This primer describes the workup and management of generalized soft tissue sarcomas of the extremity, trunk, and retroperitoneum while also highlighting the unique attributes of many subtypes. The subtypes chosen for review include those that are most common as well as those demonstrating unique behaviors or targets for management. The focus is on initial management of localized disease; however, for situations in which novel systemic agents have been discovered, the treatment of metastatic disease is discussed. This report is a reference to be used in addition to other comprehensive reviews, such as guidelines from the National Comprehensive Cancer Network, the European Society for Medical Oncology, and the American Society for Radiation Oncology. It is not a substitute for referral to an expert sarcoma center for critical pathology review and management by an experienced team. Importantly, patients who are treated at expert sarcoma centers have better outcomes than those who are not.

Total talectomy and reconstruction using unrestricted 3D printed prosthesis for pediatric talus hemangioendothelioma

Background

Epithelioid hemangioendothelioma (EHE) is an ultra-rare vascular sarcoma with an extremely low incidence and prevalence, particularly in children. We report the case of a 9-year-old girl diagnosed with EHE. There are limited reconstruction methods available following total talus resection for vascular endothelioma of the talus, and the use of a 3D-printed talus prosthesis in pediatric cases has not been previously documented.

Case presentation

A 9-year-old girl presented to our unit with swelling, pain, and limited mobility of the ankle for one month without an obvious cause. X-ray and CT imaging revealed osteolytic lesions in the talus, which was identified as a low-grade malignant tumor that had nearly completely invaded the talus and was surrounded by immature bone. The American Foot and Ankle Surgery Association (AOFAS) score was 75/100. We performed a total resection of the talus followed by unrestricted talus replacement. Three months post-operation, the child was able to walk unaided. Ankle function was assessed at 6 and 13 months post-surgery, with the AOFAS score improving from 75 to 91, indicating that her functional needs for daily life were largely met.

Conclusion

Following complete excision of the lesion, the immature bone surrounding the talus was successfully preserved using an unrestricted 3D-printed prosthesis during ankle reconstruction. Our patient demonstrated satisfactory ankle function during the 6-month follow-up. This method is both safe and stable, yielding promising results, particularly for juvenile patients.

EccDNA atlas in male mice reveals features protecting genes against transcription-induced eccDNA formation

eccDNA is a driver of many cancers and a potential intermediate in other age-related disorders. However, little is known about the mechanisms underlying eccDNA formation in healthy tissue and how aging affects these processes. Here, we present an atlas of eccDNA across seven tissues of male mice spanning four ages. EccDNA correlates with open chromatin characterized by signatures of H3K27ac and H3K4me1. Additionally, the mutational load of eccDNA on genes correlates with tissue-specific transcription and increases logarithmically as a function of transcript level. Still, a population of intron-dense genes with many splice forms remains sheltered from eccDNA formation. We also find that the total number of eccDNA molecules does not increase as mice age, unlike other types of mutations. Our data reveal a link between eccDNA formation and transcript level that may drive gene architecture in mammals.

Nab-Paclitaxel Based Chemotherapy in the Treatment of Advanced Epithelioid Hemangioendothelioma: A Single-Institution Experience

Objective

To evaluate the clinical efficacy of nab-paclitaxel based chemotherapy in the treatment of advanced epithelioid hemangioendothelioma (EHE).

Methods

Since March 2022, chemotherapy has been recommended for patients with advanced EHE characterized by large tumors (liver tumors > 10 cm or tumors in other organs > 3 cm), rapid tumor progression, severe symptoms, serosal effusion, and treatment failure. Two chemotherapy regimens were administered: nab-paclitaxel plus bevacizumab and nab-paclitaxel plus sirolimus. Clinical data and outcomes were retrospectively analyzed.

Results

From March 2022 to August 2024, 21 patients with histologically confirmed EHE who received nab-paclitaxel based chemotherapy were included. At baseline, 18 patients (85.7%) presented with tumor-related symptoms, and serosal effusion was detected in 12 patients (57.1%). Among patients with hepatic EHE, six (28.6%) had tumors > 10 cm, while six (28.6%) with EHE at other sites had tumors > 3 cm. Partial response and stable disease were achieved in 5 (23.8%) and 12 (57.1%) patients, respectively, resulting in a disease control rate of 80.9%. Symptom relief was observed in 15 of 18 patients (83.3%), and decreased serosal effusion was noted in 6 of 12 patients (50.0%). The 1- and 2-year progression-free survival rates were 50.7% and 13.5%, respectively, while the 1- and 2-year overall survival rates were 70.6% and 51.5%, respectively.

Conclusion

Nab-paclitaxel based chemotherapy may offer an effective treatment option for patients with advanced EHE exhibiting adverse prognostic factors. However, further clinical trials are required to confirm its efficacy.

CAMTA1-immunonegative epithelioid hemangioendotheliomas of the liver: a clinicopathological and molecular analysis of seven cases

Background

Epithelioid hemangioendothelioma (EHE) is a rare malignant vascular tumor. Most EHEs (>90%) cases harbor WWTR1::CAMTA1 fusion gene, and CAMTA1 immunohistochemistry (IHC) is a highly sensitive and specific tool for EHE diagnosis. However, there exist CAMTA1-immunonegative cases, the majority of which harbor YAP1::TFE3 fusion, with a few cases having more rare fusions. Liver is one of the most common sites of EHE, where the CAMTA1 subtype dominates, and the other variants are extremely rare. Hence, we focused on the hepatic CAMTA1-immunonegative EHEs to analyze the clinicopathological and molecular features of these peculiar cases.

Methods

The SNOMED search of the hospital pathology files between January 2016 to November 2023 identified 57 hepatic EHEs and 7 cases were CAMTA1-immunonegative. Fluorescence in situ hybridization (FISH), next generation sequencing (NGS) and Sanger sequencing were performed to identify the genetic change of the 7 cases.

Results

This series included 3 females and 4 males, aged from 33 to 64 years. All the 7 cases were negative for CAMTA1 IHC. Four cases were positive for TFE3 IHC and exhibited YAP1::TFE3 fusion. Another 3 cases were also negative for TFE3, while WWTR1::CAMTA1 fusion were detected by NGS in 1 case and demonstrated by FISH in all the 3 cases. Morphologically, among the 4 TFE3 rearrangement cases, 3 cases showed the TFE3-sutype morphologic appearance, while the histology of 1 case was similar to that of CAMTA1- subtype. In the 3 CAMTA1-rearranged lesions, 2 cases had classic EHE morphology, and 1 case exhibited atypical histology, with higher atypia and well-formed vessels. Surgical resection was performed on five cases and two cases were biopsied and received chemotherapy. Follow-up information was available in 6 patients (median 46 months), including 4 patients were alive without disease and 2 patients were alive with disease.

Conclusion

Our study reported 7 CAMTA1-immunonegative hepatic EHEs and most of them were TFE3-rearranged EHEs with morphology variation. Moreover, there does exist the CAMTA1-immunonegative but CAMTA1-rearranged EHE cases. Therefore, the diagnosis of EHE should be based on morphology, combined with CAMTA1 and TFE3 IHC, and if necessary, supplemented by genetic analysis including FISH and NGS, to establish correct diagnosis.

Mesenchymal Tumors of the Liver: An Update Review

Hepatic mesenchymal tumors (HMTs) are non-epithelial benign and malignant tumors with or without specific mesenchymal cell differentiation. They are relatively uncommon. Except for mesenchymal hamartoma, calcified nested stromal-epithelial tumor, and embryonal sarcoma, most mesenchymal lesions are not specific to the liver. Pathologists face challenges in diagnosing HMTs due to their diverse morphologies and phenotypic variations. Accurate diagnosis is critical for directing appropriate patient care and predicting outcomes. This review focuses on mesenchymal tumors with a relative predilection for the liver, including vascular and non-vascular mesenchymal neoplasms. It provides a thorough and up-to-date overview, concentrating on clinical and pathological features, differential diagnosis, and diagnostic approaches.

Hepatic epithelioid hemangioendothelioma with TFE3 rearrangement: a case report and literature review

Epithelioid hemangioendothelioma (EHE) is a rare low-grade malignant tumor of vascular origin. It may be confusing as its manifestations of multifocal lesions on imaging and epithelial histomorphology in pathology. EHE is easy to be mistaken for a metastatic tumor by radiologists and clinicians. Correct diagnosis and therapy are important owing to the variable clinical course and special treatment. EHEs harbor major CAMTA1 rearrangement and <5% TFE3 rearrangement. Meanwhile, EHE with TFE3 rearrangement has distinctive morphology features. Currently, there are only two cases of hepatic EHE with TFE3 rearrangement reported, we present another case here that occurred in a 34-year-old female. Both the clinician and radiologist provisionally considered it as a metastatic tumor. The tumor cells have mild atypia but infiltrative growth patterns like benign vascular tumors. Our case is unique mainly in that the absence of its characteristic well-defined vessels, and the presence of unreported morphology of intraluminal papillary proliferation of tombstone or hobnail endothelial cells. The final diagnosis of EHE with TFE3 rearrangement was made by combining morphological, immunohistochemical, and molecular test results. The patient did not receive any treatment according to her condition and no change was detected in the mass's size and number on CT images during 3.5 years of follow-up.

PI3K regulates TAZ/YAP and mTORC1 axes that can be synergistically targeted

Purpose

Sarcomas are a heterogeneous group of cancers with few shared therapeutic targets. PI3K signaling is activated in various subsets of sarcomas, representing a shared oncogenic signaling pathway. Oncogenic PI3K signaling has been challenging to target therapeutically. An integrated view of PI3K and Hippo pathway signaling is examined to determine if this could be leveraged therapeutically.

Experimental design

A tissue microarray containing sarcomas of various histological types was evaluated for PTEN loss and correlated with levels of activated TAZ and YAP. PI3K and Hippo pathways were dissected in sarcoma cell lines. The role of TAZ and YAP were evaluated in a PI3K-driven mouse model. The efficacy of mTORC1 inhibition and TEAD inhibition were evaluated in sarcoma cell lines and in vivo .

Results

PI3K signaling is frequently activated in sarcomas due to PTEN loss (in 30-60%), representing a common therapeutic target. TAZ and YAP are transcriptional co-activators regulated by PI3K and drive a transcriptome necessary for tumor growth in a PI3K-driven sarcoma mouse model. Combination therapy using IK-930 (TEAD inhibitor) and everolimus (mTORC1 inhibitor) synergistically diminished proliferation and anchorage independent growth of PI3K-activated sarcoma cell lines at low, physiologically achievable doses. Furthermore, this combination therapy showed a synergistic effect in vivo , reducing tumor proliferation and size.

Conclusions

TAZ and YAP are transcriptional co-activators downstream of PI3K signaling, a pathway that has lacked a well-defined oncogenic transcription factor. This PI3K-TAZ/YAP axis exists in parallel to the known PI3K-Akt-mTORC1 axis allowing for synergistic combination therapy targeting the TAZ/YAP-TEAD interaction and mTORC1 in sarcomas.

Clinical, Histopathological, and Immunophenotypic Spectrum of Hepatic Epithelioid Hemangioendothelioma: Eight Years' Data of a Tertiary Care Center from North India

BACKGROUND/AIMS

Epithelioid hemangioendothelioma (EHE) is an uncommon vascular tumor that commonly affects the liver. Hepatic EHE (HEHE) presents with variable clinical and histopathological features. We describe detailed clinico-histopathological features, differential diagnosis, and treatment outcomes of the cases of HEHE diagnosed in our center.

METHODS

All cases of HEHE diagnosed in our institute in the last eight years (2016-2023) were reviewed (n = 8; 11 samples) (total 36 cases of EHE; 22.2%). The clinical features, radiology, histopathology, immunophenotype, molecular features, and treatment outcomes of all cases were evaluated.

RESULTS

The median age of presentation was 49.5 years with a female: male ratio of 7:1. Abdominal pain was the commonest presentation. Approximately two-thirds of the patients had multifocal lesions. Histopathology showed purely epithelioid, predominantly epithelioid, and predominantly spindle-cell morphology in 50%, 25%, and 25%, respectively. All cases showed typical myxohyaline/fibrous stroma and organized thrombi of the portal/central veins. CD31 was the most commonly used immunostain with positivity in all cases. CAMTA1 break-apart fluorescence in situ hybridization was positive in 75% of cases, while none showed TFE3 immunopositivity. Chemotherapy was the most commonly employed therapy (n = 5) followed by surgery (n = 2). The median duration of follow-up was 26 months. Five patients were alive with disease (two patients ≥3 years), one patient died of sudden cardiac death, and two patients were lost to follow-up. Two patients developed metastatic disease at follow-up.

CONCLUSIONS

We describe the clinico-histopathological features and differential diagnosis of HEHE. This appears to be the largest case series of HEHE from India.

SARCP, a Clinical Next-Generation Sequencing Assay for the Detection of Gene Fusions in Sarcomas: A Description of the First 652 Cases

An amplicon-based targeted next-generation sequencing (NGS) assay for the detection of gene fusions in sarcomas was developed, validated, and implemented. This assay can detect fusions in targeted regions of 138 genes and BCOR internal tandem duplications. This study reviews our experience with testing on the first 652 patients analyzed. Gene fusions were detected in 238 (36.5%) of 652 cases, including 83 distinct fusions in the 238 fusion-positive cases, 10 of which had not been previously described. Among the 238 fusion-positive cases, the results assisted in establishing a diagnosis for 137 (58%) cases, confirmed a suspected diagnosis in 66 (28%) cases, changed a suspected diagnosis in 25 (10%) cases, and were novel fusions with unknown clinical significance in 10 (4%) cases. Twenty-six cases had gene fusions (ALK, ROS1, NTRK1, NTRK3, and COL1A1::PDGFB) for which there are targetable therapies. BCOR internal tandem duplications were identified in 6 (1.2%) of 485 patients. Among the 138 genes in the panel, 66 were involved in one or more fusions, and 72 were not involved in any fusions. There was little overlap between the genes involved as 5'-partners (31 different genes) and 3'-partners (37 different genes). This study shows the clinical utility of a next-generation sequencing gene fusion detection assay for the diagnosis and treatment of sarcomas.

The challenges of hepatic epithelioid hemangioendothelioma: the diagnosis and current treatments of a problematic tumor

BACKGROUND

Hepatic epithelioid hemangioendothelioma (HEHE) is a malignant vascular tumor known for its rarity. The different types of this hepatic tumor (single, multiple-nodular or diffused) indicate different prognosis and treatment plans. However, the heterogenic clinical manifestation creates a dilemma and a wide range of challenges when attending to HEHE patients. This review addresses the unique profile and clinical challenges that complicate the diagnosis and treatment of HEHE while focusing on current therapeutic strategies and their limitations.

MAIN TEXT

The unclear etiology is a challenging feature of HEHE. The exact involvement of potential risk factors and mechanism of development are still undefined. Relevant genetic alterations like WWTR1-CAMTA1 fusion have been investigated; however, they are only applicable as diagnostic markers and their influence on therapeutic efficacy is largely unknown. Other characteristics include asymptomatic manifestation, lack of unique hepatic functional alterations, high rates of misdiagnosis and late-stage identification when metastases already exist. Currently, tissue biopsy is the main tool to establish a definite diagnosis but is challenged with the limited awareness to suspect HEHE at early stages and the lack of relevant guidelines due to the rarity and the insufficiency of relevant research. The absence of treatment guidelines is the greatest challenge of HEHE. Generally, Surgical approaches are recommended due to the benefits of prolonged survival and enhanced prognosis. Nonetheless, only a minority of patients are eligible for resections while liver transplants are faced with severe insufficiency of donor organs and long wait-lists. On the other hand, a variety of non-surgical treatments (like anti-angiogenic agents, interferon alpha-2B and sirolimus) are presented with a promising potential. However, relevant studies are challenged with limited sample-sizes and lack of prospective designs.

CONCLUSION

Regardless to decades passing since its discovery, HEHE still creates a dilemma due to its challenging clinical profile and lack of treatment guidelines. Raising awareness of HEHE in clinical practices improves the ability to diagnose this rare tumor at early stages and develop stronger research strategies and treatment guidelines to regulate the medical care provided to HEHE patients.

GDF-15 Predicts Epithelioid Hemangioendothelioma Aggressiveness and Is Downregulated by Sirolimus through ATF4/ATF5 Suppression

PURPOSE

Epithelioid hemangioendothelioma (EHE), an ultra-rare sarcoma, poses therapeutic challenges because of limited efficacy of conventional chemotherapy in advanced cases, necessitating exploration of new treatment avenues and identification of novel aggressive biomarkers. This study aimed at (i) utilizing a patient-derived xenograft model of EHE and its associated cell line to assess the efficacy of sirolimus and (ii) analyzing two distinct patient cohorts to pinpoint circulating biomarkers of EHE aggressiveness.

EXPERIMENTAL DESIGN

A patient-derived xenograft model and corresponding cell line were established from a patient with advanced EHE, demonstrating consistency with the original tumor in terms of histomorphology, WWTR1::CAMTA1 fusion presence, and genomic and transcriptomic profiles. Two independent patient series were employed to investigate the association between growth/differentiation factor 15 (GDF-15) serum levels and EHE aggressiveness.

RESULTS

ELISA analyses on EHE cell culture medium and blood from EHE-carrying mice revealed the release of GDF-15 by EHE cells. Sirolimus exhibited markedly higher antitumor activity compared with doxorubicin, concurrently reducing GDF-15 expression/release both in vivo and in vitro. This reduction was attributed to the drug-induced inhibition of phosphorylation/activation of 4E-BP1 and subsequent downregulation of the GDF-15 transcription factors ATF4 and ATF5. Blood sample analyses from two independent patient series showed a significant correlation between GDF-15 and EHE aggressiveness.

CONCLUSIONS

This study identifies GDF-15 as a novel biomarker of EHE aggressiveness and underscores the superior efficacy of sirolimus compared with doxorubicin in our experimental models. The observed inhibition of GDF-15 release by sirolimus suggests its potential as a biomarker for monitoring the drug's activity in patients.

Comprehensive evaluation of clinical outcomes in hepatic epithelioid hemangioendothelioma subsets: insights from SEER Database and departmental cohort analysis

Background

Epithelioid hemangioendothelioma (EHE), is an uncommon, intermediate-grade malignant vascular tumor that can manifest in diverse organs, including the liver, lungs, and bones. Given its unique malignancy profile and rarity, there lacks a consensus on a standardized treatment protocol for EHE, particularly for hepatic epithelioid hemangioendothelioma (HEHE). This study aims to elucidate factors influencing the clinical prognosis of EHE by analyzing data from the SEER database, complemented with insights from a departmental cohort of 9 HEHE cases. Through this, we hope to shed light on potential clinical outcomes and therapeutic strategies for HEHE.

Methods

Using SEER data from 22 registries, we analyzed 313 liver cancer patients with ICD-O-3 9130 and 9133 histology. Twelve variables were examined using Cox regression and mlr3 machine learning. Significant variables were identified and compared. Clinical data, imaging characteristics, and treatment methods of nine patients from our cohort were also presented.

Result

In univariate and multivariate Cox regression analyses, Age, Sex, Year of diagnosis, Surgery of primary site, Chemotherapy, and Median household income were closely related to survival outcomes. Among the ten survival-related machine learning models, CoxPH, Flexible, Mboost, and Gamboost stood out based on Area Under the Curve(AUC), Decision Curve Analysis(DCA), and Calibration Curve Metrics. In the feature importance analysis of these four selected models, Age and Surgery of primary site were consistently identified as the most critical factors influencing prognosis. Additionally, the clinical data of nine patients from our cohort not only demonstrated unique imaging characteristics of HEHE but also underscored the importance of surgical intervention.

Conclusion

For patients with resectable HEHE, surgical treatment is currently a highly important therapeutic approach.

CDK9 Inhibition by Dinaciclib Is a Therapeutic Vulnerability in Epithelioid Hemangioendothelioma

PURPOSE

There are no effective treatment options for patients with aggressive epithelioid hemangioendothelioma (EHE) driven by the TAZ-CAMTA1 (TC) fusion gene. Here, we aimed to understand the regulation of TC using pharmacologic tools and identify vulnerabilities that can potentially be exploited for the treatment of EHE.

EXPERIMENTAL DESIGN

TC is a transcriptional coregulator; we hypothesized that compounds that reduce TC nuclear levels, either through translocation of TC to the cytoplasm, or through degradation, would render TC less oncogenic. TC localization was monitored using immunofluorescence in an EHE tumor cell line. Two target-selective libraries were used to identify small molecules that reduce TC localization in the nucleus. The ability of the shortlisted hits to affect cell viability, apoptosis, and tumorigenesis was also evaluated.

RESULTS

Basal TC remained "immobile" in the nucleus; administration of cyclin-dependent kinase (CDK) inhibitors such as CGP60474 and dinaciclib (Dina) mobilized TC. "Mobile" TC shuttled between the nucleus and cytoplasm; however, it was eventually degraded through proteasomes. This dramatically suppressed the levels of TC-regulated transcripts and cell viability, promoted apoptosis, and reduced the area of metastatic lesions in the allograft model of EHE. We specifically identified that the inhibition of CDK9, a transcriptional CDK, destabilizes TC.

CONCLUSIONS

The CDK inhibitor Dina exhibited antitumorigenic properties both in vitro and in vivo in EHE models. Dina has been rigorously tested in clinical trials and displayed an acceptable toxicity profile. Therefore, there is a potential therapeutic window for repurposing Dina for the treatment of EHE.

Progress in histology specific treatments in soft tissue sarcoma

INTRODUCTION

Soft tissue sarcomas (STS) represent a heterogenous group of rare tumors, primarily treated with surgery. Preoperative radiotherapy is often recommended for extremity high-risk STS. Neoadjuvant chemotherapy, typically based on doxorubicin with ifosfamide, has shown efficacy in limbs and trunk wall STS. Second-line chemotherapy, commonly utilized in the metastatic setting, is mostly histology-driven. Molecular targeted agents are used across various histologies, and although the use of immunotherapy in STS is still in its early stages, there is increasing interest in exploring its potential.

AREAS COVERED

This article involved an extensive recent search on PubMed. It explored the current treatment landscape for localized and metastatic STS, focusing on the combined use of radiotherapy and chemotherapy for both extremity and retroperitoneal tumors, and with a particular emphasis on the most innovative histopathology driven therapeutic approaches. Additionally, ongoing clinical trials identified via clinicaltrials.gov are included.

EXPERT OPINION

Recently there have been advancements in the treatment of STS, largely driven by the outcomes of clinical trials. However further research is imperative to comprehend the effect of chemotherapy, targeted therapy and immunotherapy in various STS, as well as to identify biomarkers able to predict which patients are most likely to benefit from these treatments.

Epithelioid hemangioendothelioma-its history, clinical features, molecular biology and current therapy

Epithelioid hemangioendothelioma (EHE) is a remarkably rare tumor arising from endothelial cells that is classified as a vascular tumor in the WHO classification. The tumor is predominantly characterized by the presence of fusion genes, such as WWTR1-CAMTA1 or YAP1-TFE3, with a minority of cases exhibiting other rare fusion genes. EHE exhibits a broad age of onset, typically presenting at ~50 years, but it is not uncommon in pediatric populations. It manifests in a variety of organs, including the liver, lung, soft tissue and bone. Initial multiple-organ involvement is also observed. The tumor's biological behavior and prognosis vary substantially based on the primary site of manifestation. From a therapeutic perspective, initial active surveillance might be considered in selected cases, although surgical intervention remains the mainstay of treatment, especially for localized single-organ involvement. Chemotherapy is administered to patients with progressive unresectable tumors. Recent advances in the biological analysis of EHE fusion genes have elucidated their diverse functions. Additionally, next-generation sequencing has facilitated the identification of other mutations beyond the fusion genes. These continuous efforts to understand the biology of the fusion genes themselves and/or the dysregulated signaling by fusion genes are expected to lead to the development of novel therapeutic strategies for EHE. This article aims to provide a comprehensive review of EHE, encompassing its historical context, clinical manifestations, molecular biology and the current state of treatment.

Congenital Vascular and Lymphatic Diseases

Over the past several centuries, the integration of contemporary medical techniques and innovative technologies, like genetic sequencing, have played a pivotal role in enhancing our comprehension of congenital vascular and lymphatic disorders. Nonetheless, the uncommon and complex characteristics of these disorders, especially considering their formation during the intrauterine stage, present significant obstacles in diagnosis and treatment. Here, we review the intricacies of these congenital abnormalities, offering an in-depth examination of key diagnostic approaches, genetic factors, and therapeutic methods.

Epigenetic determinants of fusion-driven sarcomas: paradigms and challenges

We describe exciting recent advances in fusion-driven sarcoma etiology, from an epigenetics perspective. By exploring the current state of the field, we identify and describe the central mechanisms that determine sarcomagenesis. Further, we discuss seminal studies in translational genomics, which enabled epigenetic characterization of fusion-driven sarcomas. Important context for epigenetic mechanisms include, but are not limited to, cell cycle and metabolism, core regulatory circuitry, 3-dimensional chromatin architectural dysregulation, integration with ATP-dependent chromatin remodeling, and translational animal modeling. Paradoxically, while the genetic requirements for oncogenic transformation are highly specific for the fusion partners, the epigenetic mechanisms we as a community have uncovered are categorically very broad. This dichotomy prompts the question of whether the investigation of rare disease epigenomics should prioritize studying individual cell populations, thereby examining whether the mechanisms of chromatin dysregulation are specific to a particular tumor. We review recent advances focusing on rhabdomyosarcoma, synovial sarcoma, alveolar soft part sarcoma, clear cell sarcoma, undifferentiated round cell sarcoma, Ewing sarcoma, myxoid/round liposarcoma, epithelioid hemangioendothelioma and desmoplastic round cell tumor. The growing number of groundbreaking discoveries in the field, motivated us to anticipate further exciting advances in the area of mechanistic epigenomics and direct targeting of fusion transcription factors in the years ahead.

YAP, TAZ, and Hippo-Dysregulating Fusion Proteins in Cancer

Gene fusions are well-known drivers of cancer and are potent targets for molecular therapy. An emerging spectrum of human tumors harbors recurrent and pathognomonic gene fusions that involve the transcriptional coactivator YAP1 (which encodes the protein YAP) or its paralog WWTR1 (which encodes the protein TAZ). YAP and TAZ are frequently activated in cancer and are the transcriptional effectors of the Hippo pathway, a highly conserved kinase cascade that regulates diverse functions such as organ size, development, and homeostasis. In this review, we discuss the tumors that have YAP, TAZ, or other Hippo-dysregulating fusion proteins; the mechanisms of these fusion proteins in driving their respective tumors; and the potential vulnerabilities of these chimeric oncoproteins across cancers of many origins. Furthermore, as new YAP1 and WWTR1 gene fusions are discovered, we provide a framework to predict whether the resulting protein product is likely to be oncogenic.

Molecular Alterations in Pediatric Solid Tumors

Pediatric tumors can be divided into hematologic malignancies, central nervous system tumors, and extracranial solid tumors of bone, soft tissue, or other organ systems. Molecular alterations that impact diagnosis, prognosis, treatment, and familial cancer risk have been described in many pediatric solid tumors. In addition to providing a concise summary of clinically relevant molecular alterations in extracranial pediatric solid tumors, this review discusses conventional and next-generation sequencing-based molecular techniques, relevant tumor predisposition syndromes, and the increasing integration of molecular data into the practice of diagnostic pathology for children with solid tumors.

Sarcoma of the Lung and Mediastinum

Primary sarcoma of the lung and mediastinum is rare. The diagnosis requires careful exclusion of sarcomatoid carcinoma, sarcomatoid mesothelioma, and metastases from extra-thoracic sites. This review summarizes the key morphologic, immunohistochemical, and molecular characteristics of sarcomas that are encountered in the lung and mediastinum. The tumor types discussed are synovial sarcoma, well-differentiated/dedifferentiated liposarcoma, myxoid pleomorphic liposarcoma, intimal sarcoma of the pulmonary artery, inflammatory myofibroblastic tumor, epithelioid hemangioendothelioma, primary pulmonary myxoid sarcoma, malignant peripheral nerve sheath tumor, Ewing sarcoma, and CIC-rearranged sarcoma. Relevant differential diagnoses are also addressed.

Proposed diagnostic and prognostic markers of primary malignant hepatic vascular neoplasms

INTRODUCTION

Primary malignant hepatic vascular tumors with various malignant potentials include epithelioid hemangioendothelioma (EHE) and angiosarcoma (AS), which may overlap pathologically. This study aimed to compare the pathological findings of hepatic EHE with those of AS, in association with patient outcomes.

METHODS

Fifty-nine histologically confirmed patients with 34 EHE and 25 AS were admitted to a tertiary hospital from 2003 to 2020. Their EHE and AS pathological features were compared. Immunohistochemistry for CD31, ERG, CAMTA-1, TFE3, P53, and Ki-67 labeling was performed on paraffin-embedded blocks. Markers, along with histological findings, were analyzed for the purposes of diagnostic and prognostic significance by multivariate analysis.

RESULTS

CAMTA-1 was 91.2% positive in EHE, but negative in AS (p = < 0.001). AS was significantly correlated to an aberrant p53 expression, high Ki-67 labeling, and high mitotic activity, compared to EHE (all, p = < 0.001). EHE can be classified as low grade (LG) and high grade (HG) using the prognostic values of mitotic activity and ki-67 labeling (sensitivity = 1, specificity = 1). Low grade-EHE showed significantly better overall survival than high grade-EHE (p = 0.020).

CONCLUSIONS

Immunohistochemistry for CAMTA-1, P53, and Ki-67 labeling may help distinguish EHE and AS in histologically ambiguous cases, especially small biopsied tissue. Moreover, the combination of mitotic activity and Ki-67 labeling can be a prognostic factor for EHE with various clinical features.

Uncovering the WWTR1::NCOA2 Gene fusion in low-grade myoepithelial-rich neoplasm with HMGA2 expression: A case report

We describe a case of a pleomorphic adenoma (PA) arising from the para-tracheal accessory salivary gland in a 44-year-old male harboring a novel WWTR1::NCOA2 gene fusion. To our knowledge, this novel gene fusion has not been described previously in salivary gland tumors. The patient presented with hoarseness of voice. The radiological exam revealed a mass in the upper third of the trachea involving the larynx. Histologically, the tumor consisted of bland-looking monocellular eosinophilic epithelial cells arranged in cords and sheets separated by thin fibrous stroma, focally forming a pseudo-tubular pattern. In immunohistochemistry, the tumor cells demonstrated positivity for CK7, PS100, SOX10, and HMGA2; and negativity for CK5/6, p40 p63, and PLAG1. In addition, the clustering analysis clearly demonstrates a clustering of tumors within the PA group. In addition to reporting this novel fusion in the PA spectrum, we discuss the relevant differential diagnoses and briefly review of NCOA2 and WWTR1 gene functions in normal and neoplastic contexts.

Natural compounds targeting YAP/TAZ axis in cancer: Current state of art and challenges

Cancer has become a burgeoning global healthcare concern marked by its exponential growth and significant economic ramifications. Though advancements in the treatment modalities have increased the overall survival and quality of life, there are no definite treatments for the advanced stages of this malady. Hence, understanding the diseases etiologies and the underlying molecular complexities, will usher in the development of innovative therapeutics. Recently, YAP/TAZ transcriptional regulation has been of immense interest due to their role in development, tissue homeostasis and oncogenic transformations. YAP/TAZ axis functions as coactivators within the Hippo signaling cascade, exerting pivotal influence on processes such as proliferation, regeneration, development, and tissue renewal. In cancer, YAP is overexpressed in multiple tumor types and is associated with cancer stem cell attributes, chemoresistance, and metastasis. Activation of YAP/TAZ mirrors the cellular "social" behavior, encompassing factors such as cell adhesion and the mechanical signals transmitted to the cell from tissue structure and the surrounding extracellular matrix. Therefore, it presents a significant vulnerability in the clogs of tumors that could provide a wide window of therapeutic effectiveness. Natural compounds have been utilized extensively as successful interventions in the management of diverse chronic illnesses, including cancer. Owing to their capacity to influence multiple genes and pathways, natural compounds exhibit significant potential either as adjuvant therapy or in combination with conventional treatment options. In this review, we delineate the signaling nexus of YAP/TAZ axis, and present natural compounds as an alternate strategy to target cancer.

How Molecular Discoveries Have Changed Liver Tumor Pathology: A Brief Review

CONTEXT

Recent molecular discoveries have led to improved understanding of tumor biology and the development of new diagnostic assays.

OBJECTIVE

To review primarily 3 examples of liver tumors and to briefly illustrate how recent molecular discoveries have altered clinical liver pathology practice.

DATA SOURCES

First, we will discuss fibrolamellar carcinoma, which will be the main focus of discussion, as an example for new diagnostic tests that have been developed as a result of molecular discoveries. Additional information on the role of molecular diagnostics in hepatocellular adenoma and hepatocellular carcinoma will be provided. Second, we will use the example of epithelioid hemangioendothelioma as an example of how new diagnostic tools, based on molecular discoveries, may support improved prognostication. Finally, we will use the example of intrahepatic cholangiocarcinoma as an example of a liver tumor where new molecular discoveries have identified tractable therapeutic targets and led to new effective therapies. This portion of the manuscript will also include a description of the anatomic and molecular differences between intrahepatic, hilar, and extrahepatic cholangiocarcinoma.

CONCLUSIONS

Fueled by molecular discoveries, new and better diagnostic tests and therapeutic targets have improved clinical care in patients affected by liver tumors.

Vascular tumors of intermediate malignancy: An update

The term "hemangioendothelioma" is used for endothelial neoplasms of intermediate malignancy and describes a group of rare neoplasms having biologic behavior falling in between that of the benign hemangiomas and fully malignant angiosarcomas. The hemangioendotheliomas fall into several specific, clinicopathologically and genetically distinct entities, specifically epithelioid hemangioendothelioma, kaposiform hemangioendothelioma, papillary intralymphatic angioendothelioma and retiform hemangioendothelioma (hobnailed hemangioendothelioma), pseudomyogenic hemangioendothelioma, composite hemangioendothelioma, and YAP1::TFE3-fused hemangioendothelioma. The clinical, morphologic, immunohistochemical, and genetic features, and the differential diagnosis of each of these rare entities are discussed in this review.

Hepatic Epithelioid Hemangioendothelioma in a Dog

A 5-year-old spayed female Breton dog was referred for a thyroid nodule. A total body CT scan evidenced multifocal hepatic nodules. Cytological liver samples were hemodiluted and non-diagnostic. Following a thyroidectomy, the histology was consistent with a follicular-compact thyroid carcinoma. On laparoscopy, most hepatic lobes had multifocal dark-red nodules that were biopsied for histology. Microscopically, the hepatic parenchyma in the nodules was substituted by blood channels lined by bland spindle cells but adjacent to epithelioid neoplastic cells, single or in clusters, embedded in a moderate amount of edematous collagen matrix. These cells had optically empty cytoplasmic space, occasionally containing erythrocytes (microlumina). Spindle and epithelioid cells expressed membranous-to-cytoplasmic CD31 and FVIII-RA consistent with endothelial origin. Based on morphology and immunolabelling, a hemangioendothelioma with epithelioid differentiation was diagnosed. Lesions in the liver were initially stable, showing progression with time. The dog was alive with no systemic clinical signs 36 months after laparoscopy.

Vascular Neoplasms With NFATC1/C2 Gene Alterations : Expanding the Clinicopathologic and Molecular Characteristics of a Distinct Entity

Despite significant advances in their molecular pathogenesis, skeletal vascular tumors remain diagnostically challenging due to their aggressive radiologic appearance and significant morphologic overlap. Within the epithelioid category and at the benign end of the spectrum, recurrent FOS/FOSB fusions have defined most epithelioid hemangiomas, distinguishing them from epithelioid hemangioendothelioma and angiosarcoma. More recently, the presence of EWSR1/FUS :: NFATC1/2 fusions emerged as the genetic hallmark of a novel group of unusual vascular proliferations, often displaying epithelioid morphology, with alternating vasoformative and solid growth, variable atypia, reminiscent of composite hemangioendothelioma. In this study, we further our understanding and morphologic spectrum of NFATC -fusion positive vascular neoplasms by describing 9 new cases, including soft tissue locations and novel fusion partners. Combining with the initial cohort of 5 cases, a total of 14 patients were analyzed, showing slight female predilection and an age range of 10 to 66 (mean 42 y). Twelve patients had solitary lesions, while 2 had multifocal polyostotic (pelvic bones) disease. Overall, 12 lesions were intra-osseous and 2 in soft tissue. By targeted RNA Fusion panels or FISH, there were 6 cases of EWSR1::NFATC1 , 4 EWSR1::NFATC2 , 2 FUS::NFATC2 , 1 EWSR1 rearrangement, and 1 with a novel FABP4::NFATC2 fusion. Follow-up was available in 4 patients. One patient experienced 2 local recurrences, 11 and 15 years postdiagnosis, and one patient experienced progressive disease despite multimodality treatment (curettings, embolization, radiation) over 3 years. In summary, our extended investigation confirms that NFATC -related fusions define a distinct group of vascular neoplasms with variable architecture, epithelioid phenotype, and cytologic atypia, commonly located in the bone, occasionally multifocal and with potential for local recurrence and aggressive behavior but no metastatic potential. Molecular analysis is recommended in diagnostically challenging cases with atypical histology to exclude malignancy.

Metastatic Epithelioid Hemangioendothelioma of the Bone: A Case Report and Literature Review

Epithelioid hemangioendothelioma (EHE) is an extremely rare vascular tumor, which can pose a diagnostic dilemma. It affects women more than men and is mainly found in the liver, lung, and bone. To date, there are no known predisposing factors. Limited data are available on the management of EHE at metastatic stages. The only optimal treatments to prevent metastatic dissemination are surgical resection and amputation in addition to radiotherapy at early stages. The oncologist in this rare entity plays an important role in the guided and standardized management of this disease, especially for advanced stages. In this article, we report the case of a 74-year-old patient admitted with swelling on the outer aspect of the right calf associated with pain and total functional impairment of the limb. The diagnosis favored a high-risk vascular tumor resembling EHE, confirmed by bone (tibia) and soft tissue biopsy. The patient underwent staging investigations, revealing diffuse metastases to the liver, bones, and lungs. The objective of this article is to advocate for oncological intervention in this entity, particularly in the advanced stages of the disease. Despite its rarity, the advancement of clinical trials and therapeutic recommendations remains crucial for optimal treatment.

Immunohistochemical detection of cancer genetic abnormalities

New applications of immunohistochemistry (IHC) expand rapidly due to the development of molecular analyses and an increased understanding of molecular biology. IHC becomes much more important as a screening or even a confirmatory test for molecular changes in cancer. The past decades have witnessed the release of many immunohistochemical markers of the new generation. The novel markers have extensively high specificity and sensitivity for the detection of genetic abnormalities. In addition to diagnostic utility, IHC has been validated to be a practical tool in terms of treatments, especially molecular targeted therapy. In this review, we first describe the common alterations of protein IHC staining in human cancer: overexpression, underexpression, or loss of expression and altered staining pattern. Next, we examine the relationship between staining patterns and genetic aberrations regarding both conventional and novel IHC markers. We also mention current mutant-specific and fusion-specific antibodies and their concordance with molecular techniques. We then describe the basic molecular mechanisms from genetic events to corresponding protein expression patterns (membranous, cytoplasmic, or nuclear patterns). Finally, we shortly discuss the applications of immunohistochemistry in molecular targeted therapy. IHC markers can serve as a complementary or companion diagnostic test to provide valuable information for targeted therapy. Moreover, immunohistochemistry is also crucial as a companion diagnostic test in immunotherapy. The increased number of IHC novel antibodies is broadening its application in anti-cancer therapies.

Primary vascular tumors of bone: A comprehensive literature review on classification, diagnosis and treatment

Primary vascular tumors of bone are a heterogeneous group of neoplasms, ranging from benign hemangiomas to frankly malignant epithelioid hemangioendotheliomas and angiosarcomas. Over the years, their classification has been a matter of discussion, due to morphologic similarities and uncertainty regarding biologic behavior. Over the past decade, with the development of next-generation sequencing, there has been a significant improvement in the molecular characterization of these lesions. The integration of their morphologic, immunohistochemical and molecular features has led to a better stratification, with important prognostic and therapeutic implications. Nevertheless, primary vascular bone tumors still represent a challenge for medical oncologists. Given their rarity and heterogeneity, in the last few years, there has been no significant progress in medical treatment options, so further research is needed. Here we present a review of the current knowledge regarding primary vascular tumors of the bone, correlating clinicopathologic features with tumor behavior and therapeutic approaches.

The patient perspective on sirolimus for epithelioid hemangioendothelioma (EHE): results of a community survey highlighting the importance of equitable access to treatments

Background

Epithelioid hemangioendothelioma (EHE) is an ultra-rare, vascular sarcoma with clinical presentation ranging from an indolent to an aggressive form. Over 50% of patients present with metastatic disease, requiring systemic therapy, although no systemic therapies are specifically approved for EHE. Retrospective evidence supports the activity of mTOR inhibitors (e.g. sirolimus), although available only off-label. EHE patients and advocates are therefore working to support approval of effective treatments by collecting data on patient perspectives and experiences.

Materials and methods

In February 2023, the EHE Rare Cancer Charity (UK) and The EHE Foundation (US), with other advocates, conducted a survey of perspectives and experiences of EHE patients regarding the use and accessibility of sirolimus. The survey consisted of 20 questions designed for individuals undergoing treatment, those who had been treated, or had never been treated with the drug. Widely promoted within the patient community, the online survey categorized patients into three cohorts for the analysis: liver transplant patients, non-transplant patients who had ever taken sirolimus and sirolimus-naïve non-transplant patients.

Results

The survey evaluated data from 129 patient responses from 21 countries, mostly from USA, UK, Australia, and Canada (70%). The liver transplant, sirolimus and non-sirolimus cohorts were 16%, 25% and 59%, respectively. In the sirolimus group 66% reported treatment durations exceeding one year, with 16% exceeding five years, indicating the drug's efficacy. In the non-sirolimus group, the drug was not available for 42% and for 11% sirolimus was available but not selected for treatment because of its off-label status. Overall, 87% of all patients across all cohorts expressed the importance of the drug's availability as hugely or very important.

Conclusion

The survey responses highlight the activity of sirolimus for EHE and the importance of securing a label extension for the drug delivering equitable access to this treatment for patients.

Epithelioid hemangioendothelioma (EHE) with WWTR1::TFE3 gene fusion, a novel fusion variant

Epithelioid hemangioendothelioma (EHE) is a rare endothelial sarcoma associated with a high incidence of metastases and for which there are no standard treatment options. Based on disease-defining mutations, most EHEs are classified into two subtypes: WWTR1::CAMTA1-fused EHE or YAP1::TFE3-fused EHE. However, rare non-canonical fusions have been identified in clinical samples of EHE cases and are challenging to classify. In this study, we report the identification of a novel WWTR1::TFE3 fusion variant in an EHE patient using targeted RNA sequencing. Histologically, the tumor exhibited hybrid morphological characteristics between WWTR1::CAMTA1-fused EHE and YAP1::TFE3-fused EHE. In addition to the driver fusion, there were six additional secondary mutations identified, including a loss-of-function FANCA mutation. Furthermore, in vitro studies were conducted to investigate the tumorigenic function of the WWTR1::TFE3 fusion protein in NIH3T3 cells and demonstrated that WWTR1::TFE3 promotes colony formation in soft agar. Finally, as the wild-type WWTR1 protein relies on binding the TEAD family of transcription factors to affect gene transcription, mutation of the WWTR1 domain of the fusion protein to inhibit such binding abrogates the transformative effect of WWTR1::TFE3. Overall, we describe a novel gene fusion in EHE with a hybrid histological appearance between the two major genetic subtypes of EHE. Further cases of this very rare subtype of EHE will need to be identified to fully elucidate the clinical and pathological characteristics of this unusual subtype of EHE.

Primary Pleural Epithelioid Angiosarcoma with Lung and Bone Metastases: A Case Report

Introduction

Primary pleural epithelial angiosarcoma (EAS) is an extremely rare tumor with no specific clinical symptoms. Clinical data on primary pleural EAS are limited, and misdiagnosis often occurs.

Case Presentation

The present study reports the case of a 31-year-old patient diagnosed with primary pleural EAS with lung and bone metastases. The patient presented with persistent right chest pain for 5 months and dyspnea for 2 months. Chest computed tomography (CT) scan revealed right hydropneumothorax, diffuse thickening of the right pleura, passive atelectasis, and scattered nodules in the left lung. A medical thoracoscopic pleural biopsy revealed a vasogenic tumor. To further confirm the diagnosis, positron emission tomography/CT (PET/CT) examination was recommended to determine the biopsy site after multidisciplinary discussion. Increased 18F-FDG uptake in the right pleura and hypermetabolic nodules in the right chest wall, first lumbar vertebrae, second sacral vertebrae, and bilateral iliac crest was detected via PET/CT. CT-guided chest wall and lung biopsies were performed. Immunohistochemistry of specific markers was performed according to remote consultation with a pathologist, and tumor cells with strong positive expression of CD31, CD34, and ETS-related genes led to the final diagnosis of primary pleural EAS.

Conclusion

Primary pleural EAS should be considered for hydropneumothorax of an unknown cause. PET/CT can accurately locate the lesion. The pathological examination is the basis for primary pleural EAS diagnosis. Moreover, multidisciplinary discussion and remote expert consultation can improve the diagnosis rate of primary pleural EAS.

Mesenchymal tumours of the pleura: review and update

Primary mesenchymal tumours of the pleura are uncommon and can be diagnostically challenging due to their overlapping histopathologic and immunophenotypic features. Herein we discuss selected mesenchymal tumours of the pleura, including solitary fibrous tumour, calcifying fibrous tumour, desmoid fibromatosis, synovial sarcoma, schwannoma, malignant peripheral nerve sheath tumour, inflammatory myofibroblastic tumour, follicular dendritic cell sarcoma, epithelioid hemangioendothelioma, and desmoplastic small round cell tumour. We review their clinicopathologic characteristics, along with an update on the relevant immunohistochemical and molecular features.

A cutaneous epithelioid vascular tumor harboring a TPM3::ALK fusion

Substantial progress has been made in understanding the molecular pathways associated with vascular tumors over the last two decades. In addition to mutations and copy number aberrations, fusions have emerged as significant contributors to the pathogenesis of a notable subset of vascular tumors. In this report, we present a case of an unusual intradermal vascular tumor with epithelioid cytomorphology. Immunohistochemistry revealed diffuse positivity for CD31, ERG and Factor VIII, supporting its endothelial lineage. RNA sequencing (ArcherFusion Plex) revealed the presence of an in-frame fusion between the genes TPM3 Exon 8 and ALK Exon 20. Immunohistochemistry confirmed ALK expression by the endothelial cells. To our knowledge, this is the first documented case of a vascular tumor harboring an ALK fusion. It may fall within the spectrum of epithelioid hemangiomas; nevertheless, we cannot definitively exclude the possibility of it being a distinct and potentially unique benign entity on its own.

Vasculature is getting Hip(po): Hippo signaling in vascular development and disease

The Hippo signaling pathway regulates developmental organ growth, regeneration, and cell fate decisions. Although the role of the Hippo pathway, and its transcriptional effectors YAP and TAZ, has been well documented in many cell types and species, only recently have the roles for this pathway come to light in vascular development and disease. Experiments in mice, zebrafish, and in vitro have uncovered roles for the Hippo pathway, YAP, and TAZ in vasculogenesis, angiogenesis, and lymphangiogenesis. In addition, the Hippo pathway has been implicated in vascular cancers and cardiovascular diseases, thus identifying it as a potential therapeutic target for the treatment of these conditions. However, despite recent advances, Hippo's role in the vasculature is still underappreciated compared with its role in epithelial tissues. In this review, we appraise our current understanding of the Hippo pathway in blood and lymphatic vessel development and highlight the current knowledge gaps and opportunities for further research.

Emerging mesenchymal tumour types and biases in the era of ubiquitous sequencing

New tumour types are being described at increasing frequency, and most new tumour types are now identified via retrospective review of next-generation sequencing data. This contrasts with the traditional, morphology-based method of identifying new tumour types, and while the sequencing-based approach has accelerated progress in the field, it has also introduced novel and under-recognised biases. Here, we discuss tumour types identified based on morphology, including superficial CD34-positive fibroblastic tumour, pseudoendocrine sarcoma and cutaneous clear cell tumour with melanocytic differentiation and ACTIN::MITF fusion. We also describe tumour types identified primarily by next-generation sequencing, including epithelioid and spindle cell rhabdomyosarcoma, round cell neoplasms with EWSR1::PATZ1 fusion, cutaneous melanocytic tumour with CRTC1::TRIM11 fusion, clear cell tumour with melanocytic differentiation and MITF::CREM fusion and GLI1-altered mesenchymal neoplasms, including nested glomoid neoplasm.