Bharat Rekhi, Xiaohua Qian, Andrew S Field
The first edition of the World Health Organization (WHO) reporting system for soft tissue cytopathology (WHO system) has been released recently, providing a framework of 6 categories with their individual risk of malignancies. The 6th edition of the WHO tumours of soft tissue and bone is in the pipeline, including "provisional" tumour entities, reflecting developments in the identification of new entities, particularly based on high-throughput molecular techniques and immunohistochemical stains, including surrogates to the underlying molecular signatures, along with an evolution of tumour concepts. This review focuses on some of the recently identified and provisional soft tissue tumours; newly described immunohistochemical stains and concepts that have contributed to the expanding and evolving cytopathological spectrum of soft tissue tumours, including sarcomas.