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It became apparent in recent years that in many autonomous and toxic nodules
mutations are found in the TSH receptor (TSHR) and sometimes also in the
Gs alpha coupling protein. Tonacchera et al., Pisa, Italy,
Führer et al., Leipzig, Germany, and Fiore et
al., Pisa, Italy, report that in about 50-70% of toxic or autonomous
nodules mutations are present in the TSHR. In one series of 34 patients
with toxic nodules it was looked also for mutations in the G coupling protein
that were not found to be present.
Krohn et al., Leipzig, Germany, argued that if a somatic mutation in one thyroid cell leads to the formation of autonomous nodules, these nodules should be of monoclonal characteristics. They investigated 27 toxic nodules and found in 13 somatic mutations in the TSHR and in 10 of these evidence was found for clonal expansion. In the 12 toxic nodules where no mutation was found in the TSHR or the G protein in 6 also monoclonal formation of the nodule was found. (Comment: It should be realized that not the whole gene of the TSHR and the G coupled protein have been investigated for mutations so far. It is thus not clear at the moment if all nodules are due to gene mutations or also due to other causes.) Bennedbaek et al., Odense, Denmark, compared the efficacy of percutaneous ethanol injection therapy (PEIT) and T4 suppressive therapy (TST) on regression of solitary solid cold benign thyroid nodules. Patients were randomized to either (n = 25) TST or (n = 25) PEIT. PEIT resulted in a clinical response in 50% of patients while TST resulted in regression in only 30% of patients as evaluated 12 months after therapy. Knudsen et al., Copenhagen, Denmark, investigated the prevalence of thyroid structural abnormalities and the natural history of solitary cold nodules (SCN) in an unselected population with borderline iodine deficiency (mean 24 hr iodine excretion 88 µg). People aged 41, 51, 61, and 71 years out of a population of 4.073 people were invited and 2.656 (65%) participated. Ultrasonography revealed that in 23% a multinodular thyroid structure was present. It was 3.1 times more frequent in women, 4.2 times in old age, and 1.44 times more frequent when anti TPO was present. In 65 participants (2.5%) solitary cold nodules (SCN) were found with Tc uptake. SCN was more frequent in heavy smokers, but no relation was found with sex, age, anti TPO or iodine excretion. After 2 years follow-up, 14 patients with SCN were operated but no cancers were found. Of the remaining SCN the diameter was generally unchanged after 2 years. LoPresti et al., Messina, Italy, investigated retrospectively the relationship between thyroid nodules and parity in 393 women (age 18-43 years) from a moderate area of iodine deficiency. Patients were investigated with ultrasound and, if necessary, fine needle aspiration of the nodule. In cases of suspicion thryoidectomy was followed. 275/393 women (gr A) had 1 or more pregnancies and 118/393 (gr B) were nullipara. They found that multinodularity was age related but not parity related. Furthermore, cytological features were similar in both groups as was prevalence of differentiated thyroid carcinoma (5%). |
