[Role of diagnostic and therapeutic tools in the definition of differentiated thyroid carcinoma (1800-1950)].

This paper is an attempt to evaluate the role of diagnostic and therapeutic tools to define differentiated thyroid carcinoma. At the beginning of the last century, physicians described its clinical feature: hard and invasive goiter arising after 25 and leading to death. In 1860, the surgical revolution encouraged the surgeons of goiter to treat thyroid cancer: simple goiter was viewed as precancer. From 1880, cell and tumor theories led pathologists to define microscopically thyroid cancer. In 1920, they demonstrated that the two most constant indications of thyroid epithelial malignancy were invasion of the blood vessels and distant metastasis. In 1930, radiotherapists introduced the concept of prognostic classification which combines histological criteria and patient survival for thyroid cancer. From 1940, the medical use of radioiodine led to distinguish two groups of thyroid tumors: those which are able to concentrate radioiodine and those which are not. Physicians, specialised in thyroid endocrinology, established the rules of thyroid cancer treatment. Our purpose is to analyse the epistemological and historical context of this pathology definition.