[New insights in the classification of soft tissue tumors].

Soft tissue tumours are rare and form some of the most difficult pathological subjects in medicine. The diagnosis of a soft tissue tumour goes hand-in-hand with a number of clinically relevant questions related to the therapy and prognosis (what is the classifying diagnosis?, is the proliferation reactive or neoplastic?; in the case of neoplasia: is it benign or malignant?, what is the grade of malignancy?, what is the expected clinical course?). Due to new insights in tumour diversity at a morphologic level, developments in immunohistochemistry and increasing (cyto)genetic knowledge about tumour-specific abnormalities, the known histological groups of tumours have been better characterised at the clinicopathological level, new tumour entities have been defined, old terms have been abandoned and a better understanding of tumour histogenesis has been established.