Primary malignant mesenchymal neoplasms of the larynx are rare. Sarcomas of the larynx account for <1% of all malignant laryngeal mesenchymal neoplasms. This report examines a case of a recurring laryngeal, initial benign-appearing mesenchymal tumour, which first changed its clinical phenotype without any histological signs of malignancy and later also its histological appearance with signs of malignancy. Finally, it even underwent a transformation into a higher grade of malignancy. In addition to this, the difficulties of allocating this tumour to the correct sarcoma subentity are shown.