[em]Adenoma It is doubtful whether a true adenoma of the thyroid exists, because it is difficult to differentiate histologically from a low-grade papillary carcinoma. Adenomas present as solitary nodules. In most communities the commonest nodules are colloid goitres.
Carcinomas are seen occasionally everywhere, and vary from the very slow-growing to the very malignant. In Europe the frequency of the various types is as follows. (In Africa the follicular type is relatively more common.)
Papillary carcinomas (70%), are of low-grade malignancy, and present as a nodule with or without spread to the lymph glands of the neck. The histological appearances of a needle biopsy resemble those of a normal thyroid or an ''adenoma'. Refer the patient for total thyroidectomy and block dissection of his neck on one or both sides, which will probably cure him (5 year survivals 95% and 10 year survivals 90%).
Follicular carcinomas (20%) spread to bone early, so that the first sign may be a bony secondary. He may have a lump or area of thyroid enlargement, or his thyroid may be clinically normal. If the disease is confined to his neck, refer him for a radical thyroidectomy, and a block dissection on one or both sides. If he has metastases to bone or other organs, there is little to be done. Radiotherapy often gives temporary improvement. About 5% of tumours take up radio-iodine, which is very effective. Follicular tumours range from low-grade to high- grade malignancy: (1) If he has a low-grade tumour with no metastases, he has an 86% chance of 10 year survival after radical thyroidectomy. (2) If he has metastases in his neck he has a 44% chance of survival. (3) If he has distant metastases, his prognosis is the same as for an anaplastic carcinoma.
Medullary carcinomas (3[nd]5%) have a familial incidence, and are transmitted as a Mendelian dominant. They have a characteristic histological appearance, a poor prognosis, and may be part of a system of multiple endocrine tumours.
Anaplastic carcinomas (5%) mostly occur in elderly women, and are little helped by radiotherapy; radio-iodine is not taken up. 75% of patients are dead in two years.