Colorectal Leiomyosarcoma – a Rare Tumour in GIST Era

Primary malignant mesenchymal colorectal tumours, representing a small fraction of soft tissue sarcomas, are characterised by predominance of gastrointestinal stromal tumour (GIST). After the GIST concept has been implemented in the diagnostics, the incidence of registered leiomyosarcomas has markedly decreased. The scarcity of credible cases embarrasses the analysis of tumour biological behaviour. Here we report well-documented, immunohistochemically proved, surgically treated case of colonic leiomyosarcoma (LMS) in order to broaden the published evidence by our data and to emphasize that the differential diagnosis of mesenchymal gastrointestinal tumours is not limited by GIST.