Long-term follow-up of contralateral lobe in patients hemithyroidectomizedfor solitary follicular adenoma

Objectives Since there are no available conclusive studies on the long-term evolution of remnant thyroid tissue after hemithyroidectomy in patients wh o undergo surgery for solitary follicular adenomas, we searched for such ca ses in our records to elucidate this issue. Design Search criteria were as follows: (i) presence of a single palpable t hyroid nodule with the remainder of the gland normal on palpation; (ii) cli nically euthyroid status at the time of surgery; (iii) histological diagnos is of nodule as follicular adenoma; (iv) a hemithyroidectomy operation, spa ring the contralateral lobe; (v) normal macroscopic aspect of the contralat eral lobe at the time of surgery; and (vi) at least 4 years of postoperativ e follow-up. Patients Only 47 female cases were found to meet above criteria, with a mea n age of 45.9 years (range: 23-79) at the time of surgery and a mean follow -up of 7.2 years (range: 4-32). Besides evaluating the presence or absence of antithyroid antibodies and the extranodular histology of tissue removed during surgery, a preoperative TRH test also allowed patients to be classif ied into two groups: normal extranodular thyroid (NET) (n = 32) and abnorma l extranodular thyroid (AET) (n = 15). Results Eleven of the 15 patients with AET had thyroid autoimmunity, with o r without overt histological thyroiditis, and the remaining four had subcli nical hypothyroidism with negative antithyroid antibody titres. In the enti re study population, only 28 patients received treatment with L-T4 immediat ely after surgery, none of whom had any alterations in the contralateral lo be. However, six of the nineteen patients not treated with T4 (31.6%) devel oped overt abnormalities in the contralateral lobe, including the only thre e with AET who had not received L-T4 treatment. The remaining three were tw o patients with NET, who showed postoperative TSH hyper-responsiveness to T RH (peak TSH > 25 mU/l), and one who developed a new follicular adenoma 32 years later. To date, none of the patients with NET, who had a normal TRH t est after surgery, have developed any kind of alterations in the contralate ral lobe, even those who received no L-T4 prophylactic treatment. ConclusionsThe findings of this study suggest that: (i) there is a higher r isk of follicular adenomas developing in a gland affected by thyroid autoim munity than in a previously normal gland; (ii) L-T4 therapy may prevent the formation of new nodules or the development of goitre in the contralateral lobe; and (iii) in the absence of prophylactic treatment after surgery, th e contralateral lobe of subjects with thyroid autoimmunity and/or previous subclinical hypothyroidism develops morphological abnormalities.