Among currently emerging newly characterized soft tissue tumors in the adult as well as in the pediatric popullation, a great number are consistently idendtified according to their recurrent molecular alterations, either partly such as pseudoendocrine sarcomas harboring CNNB1-gene mutations or solely so, such as GLI1-,  PRDM10-, N1RD-, or KMT2A-rearranged tumors. This trend in tumor labeling is becoming increasingly relevant presumably because of the considerable, often non specific, morphological overlap  between widely different entities, confirming the importance of the reliance on molecular genetics for precise and accurate diagnosis. In this talk we cover two such tumors  which present cytoarchitecturally as small round and epitheloid cell tumors. GLI1 (Glioma-associated oncogene homolog 1)-altered mesenchymal tumors comprise two different generally exclusive molecular subtypes , fusion or amplification of GLI-1 gene. All tumors show intense immunohistochemical expression of GLI-1 protein and consistent GLI1 RNAm overexpression irrelevant of the causal gene aberration. Most described are malignant, but a small subset conveniently termed distinctive nested glomoid neoplasm are of good prognosis, pursuing an indolent course even with regional lymph nodes metastases. No bearing on prognosis by the molecular subtype has yet been observed. Pseudoendocrine sarcomas are presently considered to be malignancies of intermediary grade with a morphology recalling that of neuroendocrine tumors and characterized by recurrent B-catenin gene mutations. It tends to be more frequent in the elderly age group, localized typically in the paravertebral area making complete surgically excision challenging. BIOGRAPHY (up to 200 words)

Yves-Marie Robin, MD, was born in Haiti on may 24th 1959 and graduated from Vassar College in Poughkeepsie, New York (USA) in 1981. He pursued a degree in the CEGEP college in Montreal (Canada) and then in 1995 graduated from the faculty of medicine at Clermont-Ferrand University (France) as a pathologist. In 2006 he became head of the department of pathology of the Oscar Lambret cancer Center (Lille, France). Dr Robin is a member of the national French Sarcoma Group which is known for its expertise and research accomplishments in the field of soft tissue sarcomas , and a member of the Mass Spectrometry translational research laboratory (PRISM) at Villeneuve d’Ascaq ( France) directed by Professor Michel Salzet. Currently he is the director of the Biology-Pathology-Genetic wing at Oscar Lambret Center since 2019 whose main objective is to set standards of laboratory practice in pathology and molecular oncology adapted to clinical needs through precision medecine and translational research. Dr Robin’s main interests are in oncopathology with a focus on soft tissue tumors and molecular characterizations.