THYROID-NODULES IN RECURRENT MULTINODULAR GOITERS ARE PREDOMINANTLY POLYCLONAL

Not only thyroid adenomas and carcinomas, but also the majority of sin gle and well delimited goiter nodules, even if morphologically heterog eneous, are of clonal origin. However, it is still unknown whether the nodules of rapidly growing, recurrent goiters are clonal or polyclona l. We investigated by PCR-based analysis of exon 1 of the human androg en receptor gene clonality of nodules grown in recurrent multinodular goiters (MNG) of 14 female patients. The total goiter volume varied wi dely between 15 ml and 170 ml. The mean age of patients undergoing sur gery for recurrent goiter at the time of their first operation was sig nificantly lower with 34.6+/-10.9 yr in comparison to 50 consecutive p atients who were operated for MNG for the first time (53.7+/-13.5 yr). The interval between first and recurrent operation was 18+/-8.5 yr. T he mean volume of well circumscribed nodules selected for the present investigation was 3.8+/-1.4 ml. Assessment of clonality in at least 2 samples of each lesion revealed a polyclonal pattern in 10 out of 14 n odules, whereas only 3 nodules were clonal and in one case the result remained unclear. The unexpected finding that most nodules within MNG, that had re-grown after a first subtotal thyroidectomy, were of polyc lonal rather than clonal composition, suggests that these lesions are generated by de novo - proliferation of cohorts of differing thyrocyte s sharing the common trait of an exceedingly high intrinsic growth rat e or alternatively, by unknown growth stimulating molecular events act ing focally on clusters of cells derived from different ancestors. In addition, the relatively young age of patients with recurrent MNG at t he time of their first surgery and the comparatively short interval be tween first and second operation point to a genetic element in the occ urrence of growth-prone thyrocytes. (J. Endocrinol. Invest. 21: 380-38 5, 1998) (C)1998, Editrice Kurtis.