Search

Quinoidal molecules based on dipyrrolyldiketone boron complexes (QPBs), in which pyrrole units were connected by a partially conjugated system as a singlet spin coupler, were synthesized. QPB, which was stabilized by the introduction of a benzo unit at the pyrrole β-positions, formed a closed-shell tautomer conformation that showed near-infrared absorption. The deprotonated species, monoanion QPB–and dianion QPB2–, showing over 1000 nm absorption, were formed by the addition of bases, providing ion pairs in combination with countercations. Diradical properties were observed in QPB2–, whose hyperfine coupling constants were modulated by ion-pairing with π-electronic and aliphatic cations, demonstrating cation-dependent diradical properties. VT NMR and ESR along with a theoretical study revealed that the singlet diradical was more stable than the triplet diradical.

High-risk plaque features and plaque burden at coronary CT angiography were associated with cardiovascular events independent of coronary hemodynamic flow parameters.

A Negishi coupling based synthesis of 1,2,4,5-tetra(9-anthryl)benzene derivatives, possessing X-shaped molecular structures, is described. The results of X-ray crystallographic analysis show that two-dimensional highly ordered packing structure of the crystalline state of the unsubstituted derivative is a consequence of intermolecular π-π and CH-π interactions between anthracene units. Photoirradiation of the unsubstituted derivative as a precipitated solution promotes intramolecular [4+4] photocycloaddition reactions between both adjacent pairs of anthracene units to produce a crystalline polycyclic product having a unique 1.700 Å long carbon-carbon single bond. Furthermore, charge-transfer complexes, displaying near-infrared absorption and emission, are generated by co-crystallization of the X-shaped unsubstituted member of the group with electron-acceptor molecules.π-Congested X-shaped 1,2,4,5-tetra(9-anthryl)benzenes were prepared. In the crystalline state, the unsubstituted derivative forms a 2D packing structure comprised of the X-shaped molecules. The product generated by intramolecular photocycloaddition of both Ant-Ant pairs possesses a very long C-C single bond of over 1.700 Å. Co-crystallization with acceptor molecules generates unique crystalline CT complexes that display NIR absorption and exciplex emission.

CIC-rearranged sarcoma is characterized by round cell undifferentiated histology, frequent expression of ETV4 and WT1, and aggressive behavior. A clinical encounter of a case with CIC-DUX4fusion and ERG/CD31 co-expression prompted us to systematically investigate ERG and CD31 expression status in 30 archival cases of CIC-rearranged sarcoma. Half (15) of them showed moderate or strong ERG expression in <5–100% of tumor cells, among which nine showed heterogeneous membranous CD31 reactivity, including four cases each showing diffuse or strong expression. None of them showed uniformly strong and diffuse ERG/CD31 co-expression; however, three cases were initially interpreted and treated as angiosarcoma without response. Except for smaller superficial tumor enrichment, the clinicopathological characteristics of these nine cases of ERG+/CD31+ CIC-rearranged sarcoma did not differ from those of remaining 21 cases. Five showed focal hemorrhagic clefts/cysts, mimicking vascular spaces. All tumors expressed ETV4 and/or nuclear WT1, and fusion to DUX4was confirmed in seven cases. Four tumors examined by next-generation sequencing harbored no CICmissense mutations. Using DNA methylation profiling, one CD31+ CIC-rearranged sarcoma was clustered with CD31− CIC-rearranged sarcomas, but distant from angiosarcomas. When compared with epithelioid angiosarcomas lacking CICrearrangements, ERG+/CD31+ CIC-rearranged sarcomas were distinguished by focal myxoid change and the entire lack of vasoformative architecture. The angiosarcomas were characterized by uniform strong expression of ERG and CD31, but none of them were found positive for ETV4 or nuclear WT1. Heterogeneous ERG/CD31 co-expression in a subset of CIC-rearranged sarcoma is a clinically relevant pitfall for angiosarcoma, as these two diseases are treated differently.

Since optical coherence tomography (OCT) was first performed in humans two decades ago, this imaging modality has been widely adopted in research on coronary atherosclerosis and adopted clinically for the optimization of percutaneous coronary intervention. In the past 10 years, substantial advances have been made in the understanding of in vivo vascular biology using OCT. Identification by OCT of culprit plaque pathology could potentially lead to a major shift in the management of patients with acute coronary syndromes. Detection by OCT of healed coronary plaque has been important in our understanding of the mechanisms involved in plaque destabilization and healing with the rapid progression of atherosclerosis. Accurate detection by OCT of sequelae from percutaneous coronary interventions that might be missed by angiography could improve clinical outcomes. In addition, OCT has become an essential diagnostic modality for myocardial infarction with non-obstructive coronary arteries. Insight into neoatherosclerosis from OCT could improve our understanding of the mechanisms of very late stent thrombosis. The appropriate use of OCT depends on accurate interpretation and understanding of the clinical significance of OCT findings. In this Review, we summarize the state of the art in cardiac OCT and facilitate the uniform use of this modality in coronary atherosclerosis. Contributions have been made by clinicians and investigators worldwide with extensive experience in OCT, with the aim that this document will serve as a standard reference for future research and clinical application.

The biradicaloid of Chichibabin’s hydrocarbon exits in a unique thermal equilibrium between closed-shell singlet and open-shell triplet forms. Conceptually, the incorporation of nonplanar aromatic groups, such as anthraquinodimethane (AQD), in these species could bring about stabilization of the individual singlet and triplet spin biradicaloids by creating a high energy barrier for conformational interconversion between folded (singlet) and twisted (triplet) forms. Moreover, this alteration could introduce the possibility of controlling spin states through conformational changes induced by chemical and physical processes. Herein, we report the preparation of AQD-containing, π-extended Thiele’s (A-TH) and Chichibabin’s (A-CH) hydrocarbons, which have highly π-congested structures resulting from the presence of bulky 9-anthryl units. The π-congestion in these substances leads to steric frustration about carbon–carbon double bonds and creates flexible dynamic motion with a moderate activation barrier between folded singlet and twisted triplet states. These constraints make it possible to isolate the twisted triplet state of A-CH. In addition, simple mechanical grinding of the folded singlet of A-CHproduces the twisted triplet.

Synovial sarcoma is characterized by variable epithelial differentiation and specific SS18-SSXgene fusions. The diagnosis is primarily based on phenotype, but fusion gene detection is increasingly being considered indispensable, with SS18break-apart fluorescence in situ hybridization (FISH) being favored in many laboratories. However, SS18FISH assay produces negative or atypical results in a minority of cases, leaving uncertainties in diagnosis and management. Here, we analyzed this challenging subset of SS18FISH-negative/atypical synovial sarcoma using RNA sequencing and monoclonal antibodies that recognize SS18-SSX and the SSX C-terminus. Among 99 synovial sarcoma cases that were previously subjected to SS18break-apart FISH, eight cases were reported as negative and three cases were indeterminate, owing to atypical signal patterns. Three of these 11 tumors (two monophasic and one biphasic) harbored novel EWSR1-SSX1fusions, were negative for SS18-SSX staining, and were positive for SSX C-terminus staining. One monophasic tumor harbored a novel MN1-SSX1fusion, and showed negative SS18-SSX expression and positive SSX C-terminus staining. Another monophasic tumor carried an SS18L1-SSX1fusion, and was weakly positive for SS18-SSX, while SMARCB1 expression was reduced. The presence of these novel and/or rare fusions was confirmed using RT-PCR and Sanger sequencing. EWSR1-SSX1was further validated by EWSR1FISH assay. The remaining six tumors (five monophasic and one biphasic) showed strong SS18-SSX expression, and RNA sequencing successfully performed in three cases identified canonical SS18-SSX2fusions. Based on a DNA methylation-based unsupervised clustering, the tumors with EWSR1-SSX1and SS18L1-SSX1clustered with synovial sarcoma, while the MN1-SSX1-positive tumor was not co-clustered despite classic histology and immunoprofile. In summary, we discovered novel and rare SSX1fusions to non-SS18genes in synovial sarcoma. The expanded genetic landscape carries significant diagnostic implications and advances our understanding of the oncogenic mechanism.

Synovial sarcoma is characterized by variable epithelial differentiation and specific SS18-SSXgene fusions. The diagnosis is primarily based on phenotype, but fusion gene detection is increasingly being considered indispensable, with SS18break-apart fluorescence in situ hybridization (FISH) being favored in many laboratories. However, SS18FISH assay produces negative or atypical results in a minority of cases, leaving uncertainties in diagnosis and management. Here, we analyzed this challenging subset of SS18FISH-negative/atypical synovial sarcoma using RNA sequencing and monoclonal antibodies that recognize SS18-SSX and the SSX C-terminus. Among 99 synovial sarcoma cases that were previously subjected to SS18break-apart FISH, eight cases were reported as negative and three cases were indeterminate, owing to atypical signal patterns. Three of these 11 tumors (two monophasic and one biphasic) harbored novel EWSR1-SSX1fusions, were negative for SS18-SSX staining, and were positive for SSX C-terminus staining. One monophasic tumor harbored a novel MN1-SSX1fusion, and showed negative SS18-SSX expression and positive SSX C-terminus staining. Another monophasic tumor carried an SS18L1-SSX1fusion, and was weakly positive for SS18-SSX, while SMARCB1 expression was reduced. The presence of these novel and/or rare fusions was confirmed using RT-PCR and Sanger sequencing. EWSR1-SSX1was further validated by EWSR1FISH assay. The remaining six tumors (five monophasic and one biphasic) showed strong SS18-SSX expression, and RNA sequencing successfully performed in three cases identified canonical SS18-SSX2fusions. Based on a DNA methylation-based unsupervised clustering, the tumors with EWSR1-SSX1and SS18L1-SSX1clustered with synovial sarcoma, while the MN1-SSX1-positive tumor was not co-clustered despite classic histology and immunoprofile. In summary, we discovered novel and rare SSX1fusions to non-SS18genes in synovial sarcoma. The expanded genetic landscape carries significant diagnostic implications and advances our understanding of the oncogenic mechanism.

The ground-state electronic structure and excited-state dynamics of a fluorene-endcapped butatriene were elucidated. Tetraphenyl-endcapped butatrienes had been known to exhibit unique photoluminescence properties in which fluorescence was completely quenched by ring closure to a fluorene scaffold. Femtosecond time-resolved microspectroscopy on the microcrystalline state and density functional theory calculations revealed that the quenching is derived from the fast nonradiative decay to the ground state and the internal conversion to the dark state.

CIC-rearranged sarcoma is characterized by round cell undifferentiated histology, frequent expression of ETV4 and WT1, and aggressive behavior. A clinical encounter of a case with CIC-DUX4fusion and ERG/CD31 co-expression prompted us to systematically investigate ERG and CD31 expression status in 30 archival cases of CIC-rearranged sarcoma. Half (15) of them showed moderate or strong ERG expression in <5–100% of tumor cells, among which nine showed heterogeneous membranous CD31 reactivity, including four cases each showing diffuse or strong expression. None of them showed uniformly strong and diffuse ERG/CD31 co-expression; however, three cases were initially interpreted and treated as angiosarcoma without response. Except for smaller superficial tumor enrichment, the clinicopathological characteristics of these nine cases of ERG+/CD31+ CIC-rearranged sarcoma did not differ from those of remaining 21 cases. Five showed focal hemorrhagic clefts/cysts, mimicking vascular spaces. All tumors expressed ETV4 and/or nuclear WT1, and fusion to DUX4was confirmed in seven cases. Four tumors examined by next-generation sequencing harbored no CICmissense mutations. Using DNA methylation profiling, one CD31+ CIC-rearranged sarcoma was clustered with CD31− CIC-rearranged sarcomas, but distant from angiosarcomas. When compared with epithelioid angiosarcomas lacking CICrearrangements, ERG+/CD31+ CIC-rearranged sarcomas were distinguished by focal myxoid change and the entire lack of vasoformative architecture. The angiosarcomas were characterized by uniform strong expression of ERG and CD31, but none of them were found positive for ETV4 or nuclear WT1. Heterogeneous ERG/CD31 co-expression in a subset of CIC-rearranged sarcoma is a clinically relevant pitfall for angiosarcoma, as these two diseases are treated differently.

We report on our investigation of C–C bonding longer than 2.0 Å, which can be realized by perpendicularly facing two fluorenyl rings in the title compound. A small orbital overlap between the distantly positioned carbon atoms is observed as a small concentration of electrons on the X-ray electron density map. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the compound originate from the in-phase and out-of-phase interactions of the overlapping orbitals, respectively, with a gap of 2.39 eV. Solid-state 13C NMR spectroscopy shows a sharp peak at 82.9 ppm for the long-bonded carbons, and a CASSCF(6,6) calculation indicates small diradical character. The experimental and theoretical analyses reveal sufficient covalent-bonding interaction in the long-bonded carbon pair.

Organic compounds with an open-shell electronic structure, in which unpaired electrons remain in the molecule, have attracted much attention in recent years due to their high reactivity and unique physical and functional properties. This paper presents my recent studies on the investigation of the properties of organic radical species through a structural organic chemistry approach to synthesize molecules with new frameworks. In particular, this paper focuses on (1) elucidation of the electronic structure of singlet biradicals and exploration of the properties characterized by the unique electronic structure, (2) molecular interpretation of the strange magnetic state of graphene nanoribbons, and (3) elucidation of the new association mode of organic radical species.This account presents our recent studies on the investigation of the properties of organic radical species through a structural organic chemistry approach to synthesize molecules with new frameworks, particularly focusing on singlet biradical character of bisphenalenyl molecules, electron localization at zigzag edges of anthenes, and association behavior of phenalenyl radicals.

Several derivatives of 1,3-dithiole[3]dendralene derivatives with two thiophene spacers (2) were synthesized. The results of an X-ray structure analysis of an analog without fused TTF units and a DFT calculation of the unsubstituted-2(2Aa) suggested that 2Aahad a structure significantly distorted between the central 1,3-dithiole (DT) ring and one of the thiophene rings. Cyclic voltammograms of tetrakis(n-hexylsulfanyl) derivatives (2Beand 2Ce) consisted of one pair of two-electron redox waves and five pairs of one-electron redox waves in correspondence with the presence of seven redox-active DT rings. The tetrakis(methylsulfanyl) or bis(ethylenedithio) derivative (2Bcor 2Bd) worked as a positive electrode material for lithium-ion batteries, and the 2Bc/Li and 2Bd/Li cells exhibited the first discharge capacities of 133–138 mAh g−1.Derivatives of a TTF-fused 1,3-dithiole[3]dendralene with two thiophene spacers (2) were synthesized. In cyclic voltammetry, six pairs of redox waves corresponding to the formation up to 27+were observed. The rechargeable batteries using 2as the positive electrode material exhibited the first discharge capacities of 133–138 mAh g−1.

On-surface Ullmann-type reactions are widely used to fabricate various carbon nanostructures in a bottom-up approach by conjugating small hydrocarbons via dehalogenation. In the reaction, the dissociated halogen atoms remain on the substrate and are usually removed by high-temperature annealing. Here, we demonstrate an alternative method in which most of bromine atoms can be desorbed from Au(111) just by depositing silicon atoms. A combination of scanning tunneling microscopy and density functional theory calculations revealed that the highly volatile silicon tetrabromine is synthesized and consequently desorbs from the surface even at room temperature. This low-temperature removal of the halogen atoms may increase flexibility in on-surface chemical reactions toward synthesis and characterization of further functionalized carbon nanomaterials.

Synovial sarcoma (SS) is an aggressive tumor that most often affects the deep soft tissues in young adults. Intrathoracic SS is rare and is associated with poor outcome, highlighting the urgent need for a novel therapeutic strategy. In the process of clinical sequencing, we identified two patients with intrathoracic SS harboring the BRAFV600E mutation. The patients were women aged 32 and 23 years, and both presented with SS18–SSX2-positive monophasic SS in the thoracic cavity. BRAFV600E mutations were detected by next generation sequencing, and validated immunohistochemically by diffuse intense positivity to BRAF V600E mutation-specific antibodies. The phosphorylated ERK (pERK) immunohistochemistry result was also positive. One patient received a combination therapy of dabrafenib and trametinib, which led to tumor shrinkage. However, the tumor growth progressed 7.5 months later with an additional NRASQ61K mutation. Immunohistochemical screening of 67 archival SS tumor samples failed to identify additional samples with BRAF V600E mutation. However, 32% of BRAF V600E-negative cases was positive for pERK, and one of the six tumors showing the highest pERK expression harbored an FGFR2-activating mutation. This is the first report of targetable BRAFmutation in a small subset of SS. Our study suggests involvement of the mitogen-activated protein kinase pathway and the potential clinical implication of BRAFmutation screening in SS.

Synovial sarcoma (SS) is an aggressive tumor that most often affects the deep soft tissues in young adults. Intrathoracic SS is rare and is associated with poor outcome, highlighting the urgent need for a novel therapeutic strategy. In the process of clinical sequencing, we identified two patients with intrathoracic SS harboring the BRAFV600E mutation. The patients were women aged 32 and 23 years, and both presented with SS18–SSX2-positive monophasic SS in the thoracic cavity. BRAFV600E mutations were detected by next generation sequencing, and validated immunohistochemically by diffuse intense positivity to BRAF V600E mutation-specific antibodies. The phosphorylated ERK (pERK) immunohistochemistry result was also positive. One patient received a combination therapy of dabrafenib and trametinib, which led to tumor shrinkage. However, the tumor growth progressed 7.5 months later with an additional NRASQ61K mutation. Immunohistochemical screening of 67 archival SS tumor samples failed to identify additional samples with BRAF V600E mutation. However, 32% of BRAF V600E-negative cases was positive for pERK, and one of the six tumors showing the highest pERK expression harbored an FGFR2-activating mutation. This is the first report of targetable BRAFmutation in a small subset of SS. Our study suggests involvement of the mitogen-activated protein kinase pathway and the potential clinical implication of BRAFmutation screening in SS.

Phenyl‐pyrazinyl‐2‐pyridyl‐2‐pyrimidinylmethane (1) has been synthesized in four steps from 2‐(chloromethyl)pyridine. This compound is chiral and expected to show metal‐coordinating ability because three of four aryl groups have the nitrogen atom at ortho‐position with respect to the central carbon atom. The X‐ray crystallographic analysis of rac‐1unambiguously revealed the tetraarylmethane framework, but the nitrogen atoms could not be assigned. The optical resolution of 1was achieved by chiral HPLC. Besides the CD spectra of the two fractions exhibited opposite signs as expected, the solvent effect on the CD spectra was also observed. According to the calculated CD curve based on time‐dependent density functional theory (TDDFT) method, the first eluted fraction is the Risomer in terms of absolute configuration. It should be noted that the CD spectrum of 1was also changed by the addition of the transition metal ions because of the formation of the metal complexes of 1. The Job plot and the electrospray ionization (ESI) mass spectrum of the solution of rac‐1in the presence of Cu2+ion revealed that the stoichiometry of 1and Cu2+was 2 : 1. A new chiral molecule, in which the nitrogen atoms are asymmetrically embedded in tetraphenylmethane framework, has been synthesized. Both the chiroptical properties and the metal‐coordinating ability are changed by the solvents.

Sigmarene, which is a Kekulé hydrocarbon with appreciable singlet biradical character originating from an o-quinodimethane scaffold, is isolated as a doubly σ-bonded dimer. The dimer dissociates into a monomeric sigmarene upon heating or photoirradiation. The monomeric species undergoes a rapid [4 + 4] cycloaddition reaction under dark conditions even at room temperature to produce the dimer. Contrarily, the monomeric sigmarene undergoes a [4 + 2] cycloaddition reaction in the presence of dienophile as an orbital symmetry allowed process. Therefore, the sigmarene shows high reactivity for both symmetry-forbidden and allowed processes in the framework of the orbital symmetry rule. This duality of reactivity of the sigmarene is consistent with the intermediate singlet biradical character (44%) estimated by a density functional theory (DFT) calculation.

We prepared a new overcrowded tristricyclic aromatic ene (TAE) and investigated its external stimuli-responsive behavior for the switching between a closed-shell folded form and an open-shell twisted form. Upon photoirradiation, the folded form transforms into the biradical twisted form, whereas by keeping the twisted form in the dark, the reverse reaction gradually occurs at room temperature. This switchable conformational change is analyzed by means of UV–vis and electron spin resonance spectroscopies, cyclic voltammetry, density functional theory calculations, and kinetic studies.

Supplemental Digital Content is available in the text.

Rechargeable batteries with Al metal as the negative electrode are promising candidates for post‑lithium-ion batteries. However, the cost of the most commonly used electrolytes, chloroaluminate ionic liquids based on 1-ethyl-3-methylimidazolium chloride (EMICl), is prohibitive. Herein, we report a novel, low-cost chloroaluminate ionic liquid electrolyte based on primary and secondary alkylamine hydrochlorides, namely, ethylamine hydrochloride (EtNH3Cl) and dimethylamine hydrochloride (Me2NH2Cl). The advantages of these alkylamine hydrochlorides over their tertiary amine counterparts (Me3NHCl and Et3NHCl) are their lower cost, odorless nature, and a lower molecular weight that would reduce the battery weight. Although the binary systems of EtNH3Cl–AlCl3and Me2NH2Cl–AlCl3are not liquids at room temperature, mixing the two systems results in an ionic liquid at room temperature. The electrodeposition of Al and intercalation of AlCl4−into graphite in this electrolyte system are demonstrated. The alkylammonium cations decompose only at potentials below −0.3 V vs. Al. The performance of Al–graphite batteries incorporating this low-cost electrolyte is comparable to that of batteries using the conventional expensive EMICl-based electrolytes under typical charge-discharge conditions. The low-cost EtNH3Cl–Me2NH2Cl–AlCl3electrolyte is expected to advance Al batteries toward practical application and commercialization.

Ambient aerosol particles at forest and suburban sites in western Japan were analyzed for imidazole compounds, such as 4 (5)-Methylimidazole (4-MI), 1-ethylimidazole (1-EI), 2-ethylimidazole (2-EI), and imidazole-2-carboxaldehyde (IC). The aerosols were collected on quartz fiber filters and extracted by the solid phase extraction method. The extract was analyzed by HPLC/Q-TOF-MS using an ion-pairing agent. The concentration of 4-MI in winter was higher than those in summer at the forest site; its concentration was highest among the analyzed imidazoles. The concentration of 4-MI in the suburban site was several times higher than the forest site. Anthropogenic activities, such as vehicle emissions, are considered to be the major source of 4-MI in this region.

Analysis of pooled clinical data has shown the safety of 3 months of dual antiplatelet therapy with everolimus-eluting cobalt–chromium stents (Co-Cr EESs). This study evaluated early and mid-term vascular responses to Co-Cr EESs in patients with stable coronary artery disease.

A ladder-like chain structure consisting of strong hydrogen bonds was developed from 1-deazahypoxanthine. In addition, electrostatic interactions derived from hydrogen-bond-induced π polarization contribute synergistically with interchain stacking to form very strong layered assemblies. Using structural data and difference Fourier diagrams obtained from single-crystal X-ray structural analyses, it was revealed that the quadrupole distribution of polarization charges on 1-deazahypoxanthine favored strong intermolecular interactions.

We report a dual-wavelength-pumped (1220 nm + 1050 nm) Tm^3+-doped ZBLAN fiber master oscillator power amplifier (MOPA) system at 813 nm for the lattice laser of the Sr optical lattice clock (OLC). Since the photodarkening effect of the Tm^3+-doped fiber is more serious in the 800 nm region, it was suppressed by applying real-time photobleaching with a 532 nm laser for obtaining stable output. We also investigated the dependence of conversion efficiency on the launched pump power ratio (P_1220 nm/P_1220+1050 nm) and found that the maximum conversion efficiency of 50% was obtained from the pump power ratio of 41%. By installing real-time photobleaching and dual-wavelength pumping, our MOPA system generated the maximum output power of 1.95 W with slope efficiency of 48%, which is the highest output power at around 810 nm from fiber laser sources, to the best of our knowledge.

A spiropyran derivative containing an acridinium and a phenoxide moieties was found to exhibit both halochromism and electrochromism in response to acid stimulation and oxidative stimulation, respectively. Variable scan‐rate voltammetric studies revealed that the acridine spiropyran undergoes a reversible conversion between a closed‐ring and an open‐ring form during the redox cycle. The presence of a ring‐opened radical cation species was demonstrated by simultaneous electrochemical ESR measurements. Dual response: An acridine spiropyran derivative undergoes a ring‐opening reaction in response to dropwise addition of an acid or application of a voltage. The equilibrium constant of the ring‐opening and ‐closing reaction of the spiropyran was greatly changed by both stimuli.

Supplemental Digital Content is available in the text.NTRKfusions in malignant tumors are therapeutic targets of tyrosine kinase inhibitors. Because they occur only in a small subset of mesenchymal tumors, knowledge regarding the corresponding histology is important to effectively identify patients who could benefit from targeted therapy. In this study, using RNA sequencing, we identified novel NTRK3fusions involving related partner genes in 2 adult bone and soft tissue tumors that met the current histologic criteria of fibrosarcoma. Case 1 involved the left radius of a 38-year-old woman, whereas in case 2, the right thigh of a 26-year-old man was affected. Histologically, both tumors consisted of the long fascicular growth of long spindle cells. The tumor in case 1 additionally showed focal myxoid changes. Tumor cells had nonpleomorphic, atypical nuclei, and lacked evidence of a specific line of differentiation. Both tumors showed widespread CD34 immunoreactivity and very limited expression of actin. RNA sequencing detected in-frame fusion transcripts of STRN(exon 3)-NTRK3(exon 14) in case 1 and STRN3(exon 3)-NTRK3(exon 14) in case 2, which were confirmed by reverse transcription polymerase chain reaction and Sanger sequencing. Pan-TRK immunostaining was diffusely positive in both cases. Fluorescence in situ hybridization showed signal patterns compatible with NTRK3rearrangements in both cases, with case 2 additionally harboring a CDKN2Ahomozygous deletion. This study expands the clinicopathologic and genetic spectrum of sarcomas associated with NTRKfusions, and suggests that CD34-positive fibrosarcoma of bone and soft tissue could be a good candidate for NTRKtesting.