The encapsulated follicular carcinoma of the thyroid. A clinicopathologic study of 35 cases.

In a retrospective study of 86 follicular carcinomas of the thyroid gland, 35 lesions were classified as encapsulated carcinomas (40.7%). In two of these, lymph node metastases were detected initially. Another patient presented with distant metastases. The biological behaviour of these 35 tumours was studied over a long-term follow-up period (0.4-19.1 years, mean 10.3 years) which featured three cases of death from thyroid carcinoma 0.4-5.0 years after thyroidectomy. Another patient suffered from local recurrence of a follicular carcinoma 13.9 years later. The morphological and clinical findings of those five patients who initially presented with metastases and/or whose follow-up registered the local recurrence of thyroid cancer or death as a result of it, were compared with the remaining 30 cases which were of a benign clinical course. Statistical analysis showed that the prognosis of encapsulated follicular carcinoma is more serious when tumours occur in patients older than 65 years of age and when the tumour diameter is 5.0 cm or more. There was a tendency towards poorer prognosis in those tumours exclusively composed of oxyphilic epithelium.