Types and staging of thyroid carcinoma
  The WHO classification of thyroid malignant tumours appears from Table 2. The most frequent types are the differentiated forms (follicular, papillary or mixed papillary-follicular) with a distribution depending on the region and iodine intake, whereas e.g. lymphomas, medullary thyroid carcinomas and secondary cancers are rare.


Table 2: WHO classification of malignant thyroid tumours

Malignant epithelial tumours:
  • Follicular carcinoma
  • Papillary carcinoma
  • Mixed papillary-follicular carcinoma
  • Undifferentiated carcinoma
  • Squamous cell carcinoma
  • Medullary carcinoma (C-cells)
Malignant non-epithelial tumours:
  • Fibrosarcoma
  • Others
Other malignant tumours:
  • Sarcoma
  • Malignant lymphoma
  • Malignant haemangioendothelioma
  • Malignant teratoma
Secondary tumours
Unclassified tumours


The outcome of thyroid carcinomas is strongly dependent on factors such as sex, age, histological type and TNM staging. Different prognostic indices have therefore been designed from different groups of reseachers (EORTC score from 1979, UICC (TNM) stage from 1987, AGES score from 1987 and AMES risk groups from 1988)(2). In each case the staging involves information such as histological type, presence of positive lymph nodes, tumour size and presence of distant metastases, which can only be available after surgical treatment of the cancer.