Clinical and histological differences in anaplastic thyroid carcinoma.

Objective: To report our experience in patients with anaplastic thyroid carcinoma and try to establish differences between cases in which the histological study showed that there was an associated thyroid carcinoma and those that were strictly anaplastic or pure.

Design: Retrospective study.

Setting: University hospital, Spain.

Subjects: 14 patients with anaplastic thyroid cancer treated over a period of 26 years; 7 presented with associated thyroid tumours and 7 were pure.

Mean outcome measures: Clinical data (age, sex, symptoms), treatment, histological study (associated thyroid disease, spread, involved lymph nodes) and follow-up.

Results: 13 of the 14 tumours had spread locally. 5 patients were treated by total thyroidectomy, 3 subtotal thyroidectomy, 5 excision of the tumour, and 1 patient had a biopsy alone. There were associated thyroid tumours in 7 cases: 2 follicular, 2 tall cell papillary, 1 solid papillary, 1 medullary and 1 Hurthle cell tumour. 12 patients died. Another 2 are still alive having survived 61 and 70 months respectively, both with associated anaplastic cancers (follicular and solid). The mean survival was 14 months (24 for associated anaplastic carcinoma and 4 for pure anaplastic carcinoma).

Conclusion: There is a subgroup of anaplastic cancers in which a better differentiated thyroid carcinoma coexists with the anaplastic carcinoma. The prognosis in this subgroup is better than that for primary pure anaplastic carcinoma.