Prevalence and Predictors of Malignancy in Contralateral Thyroid Lobe in Patients Undergoing Completion Thyroidectomy

(1) To determine prevalence of malignancy in contralateral lobe (CL) in patients undergoing completion thyroidectomy (CT) and to study complications of CT. (2) To analyze clinical, ultrasonography(USG) findings and histopathological features of the tumor in ipsilateral lobe (IL) that could predict malignancy in CL. Retrospective chart review of 40-patients who first underwent hemi-thyroidectomy for fine-needle-aspiration (FNA) diagnosed benign lesions followed by CT between September-2017 and November-2019. Histopathology reports from both surgeries, along with patient characteristics and USGfeatures of initial hemi-thyroid lobe were reviewed. Thirty-two (80%) of the 40 patients were female. Mean age of presentation was 38.2 years (Range = 19-61years). Malignancy was found in 22(55%) contralateral-lobes of 40 completion thyroidectomies performed. Multi-focality of tumor in first surgery was only factor with significant association with presence of malignancy in CL (OR = 5.53, 95% CI 1.01-30.35, p = 0.048).In terms of USG-findings, most common suspicious feature in IL was peripheral/rim calcification, with TIRADS ≥ 4 was present in 19 patients but none of features could significantly predict bilateral disease. Three (7.5%) patients developed permanent unilateral recurrent-laryngeal-nerve (RLN) palsy (2-following initial surgery and 1-following CT). Fourteen (35%) patients developed hypoparathyroidism following CT of whom 12 were symptomatic and 4(10%) proceeded to permanent hypoparathyroidism. There were no other major complication following CT. Multifocality in initial hemithyroidectomy specimen was most frequently associated with malignancy in CL. Preoperative TIRADS ≥ 4 of IL may be considered a risk factor for bilateral malignancy. CT may be performed in FNA misdiagnosed thyroid cancers as there is high prevalence(56%) of disease in CL. CT is safe and it eradicates disease in CL.