Commentary
Henrik Hellquist
Abstract
The concept of high grade transformation in human neoplasms was introduced in 1971 by the report demonstrating that 33 of 370 cases of well differentiated (low-grade) chondrosarcomas contained areas of a high-grade sarcoma. Currently at least 23 different types of primary salivary carcinomas are recognized, some of low and others of high grade malignancy.