Chondrosarcoma of the larynx.

A chondrosarcoma arising in the posterior cricoid plate is presented. The tumour gave rise to increasing inspiratory stridor: laryngectomy was performed. The tumour consisted of loose cartilaginous tissue with great predominance of highly differentiated cartilage cells and only small areas with nuclear polymorphism. This complicated the differential diagnosis between chondroma and highly differentiated chondrosarcoma. From the fact that the patient died from massive pulmonary metastases 3 1/2 years later, it is evident that the degree of malignancy of cartilaginous tumours should be determined even on small polymorphic foci. The DNA histogram for the foci of the laryngeal tumour with atypia differed distinctly from those for benign chondroma and normal cartilage, but resembled those of the pulmonary and splenic metastases and of a nasal chondrosarcoma. Photometric examination may provide an aid in the difficult differential diagnosis between chondroma and highly differentiated chondrosarcoma.