Uterine sarcomas with KAT6B/A::KANSL1 fusion represent a new entity characterized by bland morphology, commonly with hybrid features of low-grade endometrial stromal sarcoma (LG-ESS) and tumors with smooth muscle differentiation. In our study, we performed a detailed morphological, immunohistochemical, and molecular analysis of 9 cases of these tumors. Six of those had been originally diagnosed as LG-ESS, one as leiomyoma, one as leiomyosarcoma, and the remaining case as sarcoma with the KAT6B/A::KANSL1 fusion. Seven cases showed overlapping features between endometrial stromal and smooth muscle tumors, one case resembled cellular leiomyoma, and one case resembled high-grade endometrial stromal sarcoma. Immunohistochemically, the tumors showed a common expression of smooth muscle markers and endometrial stromal markers. Molecular findings showed the KAT6B/A::KANSL1 fusion in all cases (by NGS and FISH). In addition, mutations affecting genes such as TP53, PDGFRB, NF1, RB1, PTEN, ATM, RB1, FANCD2, and TSC1 were present in all 5 cases with aggressive behavior. One patient with no evidence of disease showed no additional mutations, while another harbored a mutation of a single gene (ERCC3). Of the 8 patients with available follow-up, two died of disease, 3 are currently alive with disease, and 3 have no evidence of disease. The correct recognition of tumors with the KAT6B/A::KANSL1 fusion is essential because despite the bland morphological features of most cases, these tumors have a propensity for aggressive behavior.

• Klíčová slova
• Endometrial stromal sarcoma, KAT6B/A::KANSL1 fusion, Next generation sequencing, Uterine tumor,
• MeSH
• dospělí MeSH
• endometriální stromální sarkom * genetika   patologie   MeSH
• fúze genů MeSH
• fúzní onkogenní proteiny * genetika   MeSH
• histonacetyltransferasy * genetika   MeSH
• imunohistochemie MeSH
• lidé středního věku MeSH
• lidé MeSH
• nádorové biomarkery * genetika   analýza   MeSH
• nádory dělohy * genetika   patologie   MeSH
• nádory endometria genetika   patologie   MeSH
• sarkom * genetika   patologie   MeSH
• senioři MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• fúzní onkogenní proteiny * MeSH
• histonacetyltransferasy * MeSH
• KAT6B protein, human MeSH Prohlížeč
• nádorové biomarkery * MeSH

CONTEXT.—: Non-smooth muscle uterine sarcomas are mostly represented by low-grade endometrial stromal sarcoma. However, several other rare, distinct types of uterine sarcoma are recognized, including high-grade endometrial stromal sarcoma, tumors with kinase fusions, uterine tumors resembling ovarian sex cord tumors, soft tissue-type sarcoma, and emerging entities such as KAT6A/B-rearranged tumors. The landscape of uterine sarcomas has changed, mostly because of the increasing knowledge concerning their molecular aberrations. OBJECTIVE.—: To offer a comprehensive review of the literature focusing on fusions occurring in tumors other than smooth muscle mesenchymal uterine tumors with respect to their type, frequency, and overlap between diagnostic categories and entities. DATA SOURCES.—: The data were mined from the PubMed/MEDLINE database covering the time period from January 1988 to June 2023. In total, 156 studies focusing on the problematics of fusions occurring in non-smooth muscle mesenchymal uterine tumors were selected, and thus became the basis for this review. CONCLUSIONS.—: One hundred ten fusions were identified in 703 tumors. The diagnostic significance of the molecular aberrations occurring in these tumors can be unclear in some cases. This can be related to the rare aberrations with a limited number of reported cases. Additionally, even well-known aberrations considered as specific for a certain distinct entity can occur in other lesions, the biological behavior and clinical significance of which can differ substantially.

• MeSH
• endometriální stromální nádory genetika   patologie   diagnóza   MeSH
• endometriální stromální sarkom genetika   patologie   MeSH
• fúze genů MeSH
• lidé MeSH
• nádory dělohy * genetika   patologie   diagnóza   MeSH
• sarkom genetika   patologie   diagnóza   MeSH
• Check Tag
• lidé MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

We report on 51-year-old woman who presented with brown discharge and postcoital bleeding due to myoma nascens-like polypoid mass distending cervical canal. Histologically, the tumor consisted of high-grade spindle cell component with up to 15 mitotic figures per 10 HPF and also low-grade leiomyoma-like areas with focal myxoid change and so far undescribed cytoplasmic signet ring cell change. Immunohistochemically Desmin, actin, and h-caldesmon were negative. Conversely, BCOR positive expression was coupled with Cyclin D1 positivity and was antibody clone dependent. The molecular NGS and FISH study identified reciprocal fusion gene ZC3H7B-BCOR. In conclusion, these findings further support the idea of routine reflex molecular testing of uterine mesenchymal tumors with unusual clinical presentation or in case malignancy is suspected. Lastly, we suggest ZC3H7B-BCOR rearranged high-grade endometrial stromal sarcoma might be considered as a tumor suitable for BCL6-targeted treatment.

• Klíčová slova
• BCOR protein, Endometrial stromal, Female, Fusion, Oncogene proteins, Proto-oncogene proteins, RNA-binding proteins, Repressor proteins, Sarcoma, Signet ring cell, ZC3H7B protein,
• MeSH
• endometriální stromální sarkom genetika   patologie   MeSH
• karcinom z prstenčitých buněk diagnóza   patologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• nádorové biomarkery genetika   MeSH
• nádory dělohy patologie   MeSH
• nádory endometria genetika   patologie   MeSH
• proteiny vázající RNA metabolismus   MeSH
• protoonkogen Mas MeSH
• protoonkogenní proteiny genetika   metabolismus   MeSH
• represorové proteiny metabolismus   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH
• Názvy látek
• BCOR protein, human MeSH Prohlížeč
• MAS1 protein, human MeSH Prohlížeč
• nádorové biomarkery MeSH
• proteiny vázající RNA MeSH
• protoonkogen Mas MeSH
• protoonkogenní proteiny MeSH
• represorové proteiny MeSH
• ZC3H7B protein, human MeSH Prohlížeč