Differentiated thyroid cancers were found in mother and son. The diagnosis was made first in the boy where papillary and follicular cancer with lymph node involvement and lung metastatic dissemination was diagnosed at the age of 9. Treatment by surgery, radioiodine and thyroid hormones was highly effective. 1 year later, thyroid surgery was performed on his mother but the diagnosis of poorly differentiated follicular thyroid cancer was made only 4 years later when the primary tumour was already unresectable and distant metastases present. In spite of treatment, the disease followed a lethal course in the mother. The familial occurrence of’differentiated thyroid cancer is extremely rare and this report is the first where neither previous radiation exposure nor familial colonic polyposis were detected.

Metastatic dissemination of differentiated cancer was studied in a personal group with the following results. Invasion of cancer to adjacent structures can be encountered even in children with typical increase with age. The lymphatic spread to regional lymph nodes is typical of papillary cancers and in young patients. The same type of spread without the age-dependent decrease can also be proved, with lower incidence, in follicular cancers. Pulmonary metastases are frequently the only type of distant metastases and may originate from previous spread to lymph nodes. The isolated bone metastases are probably brought about through the vertebral venous system. Patients having multiple bone metastases or both bone and lung lesions are probably the only typical examples of metastasizing through the systemic blood flow. As the above types of distant metastases carry different prognosis they should also be recognized by the TNM system.

Fifteen patients with differentiated thyroid cancer were examined following 131I thyroid ablation, of these seven were examined after radio-iodine therapy to disseminated neck cancer. They had no further radio-iodine uptake and were evaluated using a 201Tl scan. In thirteen patients there was a good correlation between the results and the clinical diagnosis, showing no uptake in seven subjects with negative clinical findings, and positive delineation of tumour tissue in the neck region in six patients. The remaining two patients with lymph node metastases after previous radio-iodine irradiation showed marked clinical regression of the metastases with absent uptake of both 131I and 201Tl, probably due to radiation-induced changes. The comparison of thallium scans with plasma thyroglobulin levels showed certain differences (high plasma thyroglobulin without any proof of remaining thyroid tissue in one patient and normal/low plasma thyroglobulin in the presence of a tumour in two patients) but both measurements could give additional information. It is believed that while in the differential diagnosis of a thyroid nodule no important information could be expected of scanning (compared with the high value of aspiration biopsy), the evaluation of patients without 131I uptake by 201Tl scans could provide important information for further therapy.