Pathology of thyroid tumours

Palpable thyroid nodules occur in 4–7% of the population but most are benign: dominant nodules in nodular goitre or follicular adenomas. Thyroid cancer is the commonest type of endocrine malignancy but accounts for only ∼1% of malignant tumours. Most arise from thyroid follicular cells, with about 80% papillary carcinoma and 10–15% follicular carcinoma. Medullary carcinoma arising from C cells accounts for about 10% of cases.In this contribution, the approach to differential diagnosis, the specific features of each type and the prognosis are discussed. What is known of the molecular pathogenesis is presented. The more important of the rarer types of tumour are listed.