Extremely aggressive course in a poorly differentiated thyroid carcinoma presenting a double mutation of the TERT promoter

BRAF and TERT oncogenes hotspot mutations are associated with a more aggressive outcome in thyroid carcinomas (TC). TERT promoter (pTERT) mutations (C228T and C250T) are related to cancer growth and reduced overall- and disease-free survivals in TC. We report a patient followed up for 8 years with a poorly differentiated thyroid carcinoma (PDTC) presenting an extremely aggressive course, who developed a large volume of metastases in a short period. Molecular analysis of the primary tumor revealed two pTERT mutations (C228T and C250T), and no BRAF V600E mutation. pTERT mutations C228T and C250T have been described as mutually exclusive, indicating that one mutation is enough for telomerase activation and exerts its action in thyroid tumorigenesis. This report describes both pTERT hotspot mutations in the same PDTC patient presenting a very aggressive course, even for PDTC, suggesting a relationship between the two events. However, more studies are needed to prove this causality.

Thyroid suppression test with L-thyroxine and [99mTc] pertechnetate

OBJECTIVE

The thyroid suppression test is still used in some centres as an adjunt in the diagnosis of autonomous functioning thyroid nodules. With the purpose of minimizing the disadvantages of the original T3 suppression test, we have evaluated the efficacy of a method using L-thyroxine as TSH suppression agent and [99 mTc] pertechnetate as radiopharmaceutical.

DESIGN

Open nonrandomized prospective study

MATERIALS AND METHODS

A control group of 15 normal volunteers (11 males, 4 females; 21-35 years, mean 26.4 years) and a patient group of 20 patients (18 females, 2 males; 27-83 years, mean 53.6 years) divided into 4 subgroups, were studied: 7 patients with autonomous functioning nontoxic nodules, 3 with autonomous functioning toxic nodules, 7 with Graves disease and 3 with nonautoimmune diffuse toxic goitre. Baseline thyroid uptake and imaging were begun 20 minutes after an intravenous injection of 370 MBq (10 mCi) of [99 mTc] pertechnetate. This was followed by a single daily intake of 2 microg/kg of L-thyroxine, for 10 days. Thyroid imaging and uptake were then repeated.

RESULTS

In the control group [99 mTc] pertechnetate uptake after L-thyroxine suppression had a mean reduction of 75.8 +/- 7.69% (58-87%) in comparison to the baseline level. All subjects were euthyroid by clinical and laboratory criteria and none complained of side-effects, despite significant suppression of TSH levels. In the patient group, thyroid uptake after suppression decreased in 10 patients (maximum reduction 39%), was unchanged in 2 patients and increased in the remaining 8 patients.

CONCLUSION

The method described was efficient for demonstration of autonomous thyroid tissue, since none of the patients showed significant reduction of thyroid uptake after L-thyroxine suppression compared with the control group. This test was as effective as the original T3 suppression test, but more convenient to the patient: no side-effects, ease of hormonal intake, low dosimetry and short stay in the nuclear medicine laboratory.