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Reports on the discussion during a symposium on the topic related to mesenchymal lesions of the uterus. Diagnostic aspects of uterine smooth muscle tumors; Description of uterine tumors with mixed mixed-epithelial and mesenchymal elements; Overview of several types of mesenchymal tumors.

Reports on the discussion during the symposium on the topic related to mesenchymal lesions of the uterus. Diagnostic aspects of uterine smooth muscle tumors; Description of the endometrial stromal tumors of the uterus; Overview of malignant mullerian mixed tumors.

Aims: NTRK-rearranged sarcomas of the female genital tract mainly occur in the uterus (more commonly cervix than corpus) and are characterized by a "fibrosarcoma-like" morphology and NTRK gene rearrangements. These neoplasms may exhibit histological overlap with other entities and can present diagnostic difficulties without molecular confirmation. Pan-TRK immunohistochemistry was developed to identify tumours harbouring NTRK rearrangements. The aim of this study was to characterize pan-TRK immunohistochemical expression in a large cohort of gynaecological mesenchymal neoplasms and investigate the utility of pan-TRK immunohistochemistry to distinguish NTRK-rearranged sarcoma from its mimics., Methods and Results: A total of 473 gynaecological mesenchymal tumours (461 without known NTRK fusions and 12 NTRK-rearranged sarcomas) were selected. Pan-TRK immunohistochemistry (EPR17341, Abcam) was performed on whole tissue sections and tissue microarrays. Molecular interrogation of pan-TRK positive tumours was performed by RNA sequencing or fluorescence in situ hybridization (FISH). Of the 12 NTRK-rearranged sarcomas, 11 (92%) exhibited diffuse (≥70%) cytoplasmic pan-TRK staining with moderate/marked intensity, while the other was negative. Eleven (2.4%) additional tumours also exhibited pan-TRK immunohistochemical expression: three low-grade endometrial stromal sarcomas, seven high-grade endometrial stromal sarcomas, and an undifferentiated uterine sarcoma. Molecular confirmation of the absence of NTRK rearrangements was possible in nine of these tumours. Of these nine neoplasms, seven exhibited focal/multifocal (<70%) pan-TRK cytoplasmic staining with weak/moderate intensity., Conclusion: Even though pan-TRK immunohistochemical expression is not entirely sensitive or specific for NTRK-rearranged sarcomas, these neoplasms tend to exhibit diffuse staining of moderate/strong intensity, unlike its mimics. Pan-TRK should be performed in monomorphic uterine (corpus and cervix) spindle cell neoplasms that are negative for smooth muscle markers and hormone receptors and positive for CD34 and/ or S100. Ultimately, the diagnosis requires molecular confirmation., (© 2023 John Wiley & Sons Ltd.)

Aims: Gynandroblastoma is a rare ovarian sex cord-stromal tumour characterised by the presence of both male (Sertoli and/or Leydig cells) and female (granulosa cells) components. We investigated the mutational status of DICER1, FOXL2 and AKT1 genes at hot-spot regions that are known to be the key driving events in the development of Sertoli-Leydig cell tumour (SLCT), adult granulosa cell tumour (aGCT) and juvenile granulosa cell tumour (jGCT), respectively, to gain insights into the molecular pathogenesis of gynandroblastoma., Methods and Results: Sixteen cases of gynandroblastoma were studied. All contained SLCT or Sertoli cell tumour components. aGCT and jGCT components were identified in seven and 10 cases, respectively, with one presenting both components. Heterozygous hot-spot mutations in the RNase IIIb domain of DICER1 were discovered in three cases, including one case with heterologous mucinous elements, all of which were composed of moderately or poorly differentiated SLCT and jGCT components, and harboured the mutations in both histological components. None of the 16 cases displayed mutations at the p.C134W (c.402C→G) of FOXL2 or within the pleckstrin-homology domain of AKT1. All cases showed FOXL2 immunostaining in both male and female components., Conclusion: DICER1 hot-spot mutation is the key-driving event in a subset of gynandroblastomas containing components of SLCT and jGCT. Gynandroblastomas composed of SLCT and jGCT may represent morphological variants of SLCT. The molecular basis of gynandroblastoma containing a component of aGCT is different from pure aGCT., (© 2018 John Wiley & Sons Ltd.)

Aims: The diagnosis of adult-type granulosa cell tumours of the ovary (aGCT) is based on histomorphology aided by immunohistochemical staining for sex cord markers. Recently a single, recurrent somatic point mutation (402C→G) in FOXL2 was described in aGCT. We have investigated the impact of FOXL2 mutation testing in a large cohort of aGCT diagnosed previously by conventional histology and immunohistochemistry., Methods and Results: Formalin-fixed, paraffin-embedded tissue cores from a cohort of 52 aGCT diagnosed previously by expert gynaecopathologists were analysed immunohistologically. FOXL2 mutation status was determined by Sanger sequencing and high-sensitivity TaqMan allelic discrimination assay. Histomorphology was reassessed by two expert gynaecopathologists. FOXL2 mutation analyses could be performed successfully in 46 cases, 40 of which were positive for the c.402C>G mutation, confirming a diagnosis of aGCT. In the six cases negative for the c.402C>G mutation, one case was confirmed on review as FOXL2 wild-type aGCT, whereas in the remaining five cases diagnoses other than aGCT were made., Conclusion: In cases where a diagnosis of aGCT is a consideration and unequivocal diagnosis is not possible based on morphology and routine immunostains, FOXL2 mutation testing can help to confirm the diagnosis. It is particularly relevant for accurate subclassification within the group of sex cord-stromal tumours., (© 2013 John Wiley & Sons Ltd.)

Aims: The recent recognition that ovarian carcinoma is composed of five distinct disease entities has served to increase the value of accurate histotyping. Reliable identification of histotypes is essential for the success of studies testing novel therapies, as well as for biomarker discovery research. The aim of this study was to examine the utility of a nine-marker immunohistochemical (IHC) panel, designated the Calculator for Ovarian Subtype Prediction (COSP), to reliably reproduce the consensus diagnosis of two expert gynaecological pathologists., Methods and Results: A total of 423 cases from the AGO-OVAR11 trial were evaluated using the COSP IHC panel, and compared to original diagnoses from >100 local contributing pathologists and independent expert gynaecopathology review. The overall concordance between COSP and expert review was 89%; in cases where a local pathologist's diagnosis was confirmed by COSP, the expert gynaecopathologist also agreed in 97.5% of cases., Conclusions: The incorporation of COSP into a high-throughput diagnostic review algorithm will decrease the need for expert review by identifying a small number of difficult cases that truly require expert review. This modification will serve to increase the efficiency of the diagnostic review process, which will probably serve to reduce operational costs and expedite translational studies on ovarian carcinoma., (© 2013 John Wiley & Sons Ltd.)