[Rare neoplastic and common pathologies of the thyroid]

Observation of three cases of rare thyroid pathology (medullary carcinoma, thyroid lymphoma, De Quervain's subacute thyroiditis) triggers a discussion of the need to take due account of such rare pathologies in preoperative differential diagnosis in order to avoid giving the wrong treatment. The fact that extemporary histological examination is no help in such situations is also discussed.