New and emerging entities of soft tissue sarcomas with uncertain differentiation

Abstract

In recent years, large scale genetic analyses have become more prevalent and more accessible in pathology departments. Their widespread application has revealed an ever increasing number of distinct genetic alterations in soft tissue tumours that had been hard to classify on morphological and immunohistochemical grounds. It has let to recognition of new entities, some of which are still in their emerging process. This review will attempt to give an overview of recently established entities within the group of tumours with uncertain differentiation such as primitive tumours with rearrangements of CIC and PATZ1 and sarcomas with BCOR alterations, as well as emerging entities such as pseudoendocrine sarcoma, and mesenchymal tumours with Gli1 alternations. Finally, TRAF7-mutated fibromyxoid spindle cell tumour will be illustrated as a possible new entity with only a small number of described cases to date.