Abstract
(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.
Keywords: Completion thyroidectomy, Well differentiated thyroid cancer, Bilateral thyroid cancer, FNA misdiagnosed thyroid cancer
Introduction
Ultrasonographic findings highly suspicious of malignancy include solid components, hypoechogenicity, microlobulated or irregular margins, microcalcifications and taller than wide shape [1]. Ultrasonography also guides a pathologist to perform a FNA from suspicious areas of thyroid thus increasing its sensitivity. However diagnosing a thyroid carcinoma preoperatively still remains a challenge despite improvements in FNA and radiological techniques (Ultrasonography in particular) [2–4]. Across various literatures, the risk of malignancy of a nodule with an indeterminate FNAC ranges from 12 to 42% [5–10].
Hemithyroidectomy performed for FNA diagnosed benign lesions frequently require completion thyroidectomy, if found to be malignant post-operatively, which is not without risks and increased rate of complications [2]. A 2–5% risk of permanent recurrent laryngeal nerve (RLN) damage and 8–15% risk of transient hypoparathyroidism has been reported [2]. Permanent hypoparathyroidism is rarer occurring in 3% of cases [2]. However the rationale of performing an elective completion thyroidectomy (CT) for well differentiated thyroid carcinoma includes better clinical response to radioiodine ablation, accurate post-operative thyroglobulin monitoring and removal of any synchronous tumor in the contralateral lobe [2, 5, 11–15]. Recent ATA guidelines also recommend CT in high risk disease and/or when postoperative RAI therapy is indicated [16].
Due to the lack of definitive features or methods to identify the presence of disease in the contralateral lobe, the histo-pathological analysis of the hemithyroidectomy becomes crucial in deciding for the need of CT.
Our study aims at finding the rate of contralateral lobe involvement and complications following CT, and the histopathological as well as USG features of the ipsilateral hemithyroid lobe which may predict presence of tumor in contralateral lobe.
Methods
In this retrospective review, patients who had undergone initial hemithyroidectomy followed by CT, for initially FNA misdiagnosed well differentiated thyroid cancers, between November 2017 and November 2019, were included in this study. Patients who had undergone their first surgery in any other institute were excluded from the study. Additionally patients with similar suspicious nodules on USG in bilateral thyroid lobes were also excluded from the study as such patients mostly underwent near total thyroidectomy as the initial surgery. Presence of comorbidities like diabetes and hypertension were not considered as exclusion criteria. A total of 40 patients met the inclusion criteria. Additionally 2 patients whose initial histopathology was poorly differentiated carcinoma were also excluded from this study.
All patients pre-operatively underwent high resolution ultrasonography and FNAC following routine thyroid function test. Routine blood investigations were done in preparation for initial surgery. CECT scan was done only when the thyroid was bulky with possible retrosternal extension or compression of trachea. Additionally serum calcium levels were done pre-operatively in all patients and were repeated after 24 and 72 h of surgery. Initial hemithyroidectomy was performed for all cases. Flexible nasopharyngolaryngoscopy was also done pre and post-operatively to assess the vocal cord status.
Following the histopathology report, CT with selective neck dissection (level 6 ± lateral neck dissection) was performed. The indication for CT in our institution was presence of malignancy in initial hemithyroidectomy specimen and the willingness of the patients and most of them would undergo CT. CT was performed by contralateral extension of the previous Kocher’s incision and with excision of the previous scar. Serum calcium was again repeated at 24 and 72 h postoperatively and so was nasopharyngolaryngoscopy on the first post-operative day. Hypoparathyroidism was defined as serum calcium levels below 8 mg/dl irrespective of whether the patient developed symptoms of hypocalcaemia. Temporary hypoparathyroidism was defined as patients requiring calcium and/or vitamin D3 supplementation for less than 6 months with permanent hypoparathyroidism defined as those requiring supplementation beyond 6 months.
Pre-operative USG features and histopathology reports of both initial and completion surgery were analyzed. The initial hemithyroid specimen was evaluated with regards to histological type, size, tumor capsule status, lympho-vascular involvement, extra-thyroidal extension (ETE), lymph node metastasis and multifocality. Based on pathology of contralateral lobe post completion surgery, patients were divided into 2 groups i.e. benign CT group and malignant CT group. In our study, multifocality was defined as the presence of more than one malignant focus in theresected thyroid lobe, irrespective of size, and tumor size in a multifocal malignancy corresponded to the largest focus in that lobe. All the cases in our study with tumor in contralateral lobe had the same histological type as the ipsilateral lobe.
Statistical analysis of categorical variables was done with Chi-Square test. Binary logistic regressions were used to confirm the independent correlations with bilateral disease the in subsets of our study sample. The calculations were done using SPSS statistics version 21.Institutional ethics committee of institution, IEC, approved the study.
Results
Demographics
Of the 40 patients, 32 (80%) were females with 15 in the benign and 17 in the malignant contralateral groups. On the other hand 8 (20%) patients were male of who 5 belonged to the malignant contralateral group. Mean age of presentation was similar in both groups i.e. 38.1 (± 16.3) years in the benign completion and 39.4 (± 15.2) years in the malignant completion groups. The mean duration between initial surgery and completion thyroidectomy was also similar i.e. 18.1 ± 2.3 days in the benign completion and 18.9 ± 2.9 days in the malignant completion group (Table 1). Primary FNAC showed adenomatoid goiter (Bethesda-II) in 22 patients (55%), follicular neoplasm (Bethesda-IV) in 12 (30%), atypia of undetermined significance (Bethesda-III) in 5 (12.5%) and Hashimoto’s thyroiditis (Bethesda-II) in one patient (2.5%). Two patients whose pathology after first surgery was poorly differentiated carcinoma were excluded from the study.
Table 1.
Demographics of the study population
| N = 40 | Benign completion thyroidectomy group (N = 18) | Malignant Completion thyroidectomy group (N = 22) | p value |
|---|---|---|---|
| Gender | |||
| Male (8) | 3 | 5 | 0.63 |
| Female (32) | 15 | 17 | |
| Mean age of presentation in years | 38.1 (± 16.3) | 39.4 (± 15.2) | 0.83 |
| Mean duration between initial surgery and completion thyroidectomy in days | 18.1 (± 2.3) | 18.9 (± 2.9) | 0.75 |
Pathology
In the initial hemithyroidectomy specimen, 33 patients had papillary carcinoma, 4 had follicular carcinoma, 2 hadmedullary carcinoma and 1 case was of hurthle cell carcinoma. The rest of pathological features have been enumerated in Table 2.
Table 2.
Demographics and histopathological charasteristics of initial ( ipsilateral) hemithyroidectomy and its association with bilateral disease (contralateral malignancy)
| Demographics and histopathological charasteristics of initial (ipsilateral) hemithyroidectomy (n = 40) | Benign completion thyroidectomy group/unilateral (N = 18) | Malignant completion thyroidectomy group/bilateral (N = 22) | p value | |
|---|---|---|---|---|
| Age | < 55 | 8 | 10 | 0.94 |
| ≥ 55 | 10 | 12 | ||
| Sex | Male | 3 | 5 | 0.63 |
| Female | 15 | 17 | ||
| Lymphovascular involvement | Present | 2 | 3 | 0.81 |
| Absent | 16 | 19 | ||
| Level 6 Lymph node involvement | Present | 5 | 7 | 0.78 |
| Absent | 13 | 15 | ||
| Extrathyroidal extension* | Present | 1 | 2 | 0.64 |
| Absent | 17 | 19* | ||
| Histology | Papillary carcinoma | 15 | 18 | 0.9 |
| Follicular carcinoma | 2 | 2 | ||
| Others** | 1 | 2 | ||
| Tumor capsular involvement* | Present | 2 | 2 | 0.87 |
| Absent | 16 | 19* | ||
| Multifocality | Present | 2 | 9 | 0.03 |
| Absent | 16 | 13 | ||
| Size | < 1 cm | 10 | 12 | 0.68 |
| 1–4 cm | 4 | 7 | ||
| ≥ 4 cm | 4 | 3 | ||
The differences which is statistically significant is shown in bold
*N = 39 as Extrathyroidal extension and tumor capsular involvement couldn’t be assessed pathologically in 1 case
**2 cases of medullary carcinoma (both bilateral) and 1 case of hurthle cell carcinoma (unilateral)
Following completion thyroidectomy, 22 (out of 40) i.e. 55% contralateral lobes were found harboring malignancies.
Of the 22 cases, 18(45%) were papillary carcinomas (PTC), 2 (5%) medullary carcinomas (MTC) and 2(5%) follicular carcinomas (FTC). Of the 18 PTCs, 10 were microcarcinomas (size < 1 cm). Both cases of medullary carcinoma were found in males and neck dissection in both revealed bilateral nodal metastasis.
With regards to lympho-vascular involvement of ipsilateral lobe, 3 patients were found to have bilateral disease as compared to 2 with unilateral (Table 2). Sentinel level VI lymph node biopsy was positive in 12 patients, of whom 7 had bilateral disease. Similarly ETE was present in just 3 of initial hemithyroid specimens of who 2 had bilateral disease. ETE of 1 case couldn’t be evaluated on pathology. Multifocality was found in 11 of the 40 ipsilateral lobes of whom 9 were found to be harboring bilateral disease.
In the malignant contralateral lobe, all tumors were microcarcinomas (< 1 cm), with identical histology as the ipsilateral lobe without any ETE or thyroid capsular involvement. 5 cases had positive contralateral nodal positivity on completion, 2 of whom were medullary carcinoma and 3 of papillary carcinoma.
Ultrasonography
As mentioned before, only cases with significant USG findings in ipsilateral lobe or additional benign findings in contralateral lobe were included in the study. Cases of similar suspicious USG findings in both lobes were excluded.
TI-RADS scoring system was used for risk stratification. Table 3 presents the high risk features seen in pre-operative USG, TI-RADS score and association with unilateral/bilateral malignancy groups. In our study, the most common suspicious feature in USG of the ipsilateral lobe pointing to a malignant etiology (FNAC—benign), happens to be presence of peripheral/rim calcifications (92.5% accuracy) followed by hypo-echogenicity (70%) (Table 3). But none of the USG features of ipsilateral lobe could significantly predict contralateral disease in the absence of suspicious features in the same.
Table 3.
USG characteristics, TI-RADS score of ipsilateral thyroid lobe (initial thyroidectomy) and its association with bilateral disease (Contralateral malignancy)
| N = 40 | Benign contralateral group/unilateral (N = 18) | Malignant contralateral group/bilateral (N = 22) | Total (N = 40) | p value | |
|---|---|---|---|---|---|
| Composition | Cystic | 2 | 2 | 4 | 0.45 |
| Mixed-Solid/Cystic | 4 | 9 | 13 | ||
| Solid | 12 | 11 | 23 | ||
| Hypoechoic Echogenicity | Yes | 13 | 15 | 28 (70%) | 0.78 |
| No | 5 | 7 | 12 | ||
| Shape | Wider than tall | 9 | 10 | 19 | 0.77 |
| Taller than wide | 9 | 12 | 21 | ||
| Margin | Smooth | 16 | 18 | 34 | 0.53 |
| Irregular | 2 | 4 | 6 | ||
| ETE | 0 | 0 | 0 | ||
| Vascularity | Central/Intranodular | 10 | 14 | 24 | 0.6 |
| Peripheral | 8 | 8 | 16 | ||
| Echogenic foci | Macrocalcifications | 2 | 1 | 3 | 0.72 |
| Rim calcifications | 15 | 20 | 35 (92.5%) | ||
| Punctate echogenic foci | 1 | 1 | 2 | ||
| TIRADS score | TR1, TR2 | 2 | 0 | 2 | 0.78 |
| TR3 | 9 | 10 | 19 | ||
| TR4 | 5 | 10 | 15 | ||
| TR5 | 2 | 2 | 4 |
Predictors of Bilateral Disease
Initial analysis of our study revealed that multifocality identified in the initial hemithyroid specimen was the only significant predictor of contralateral malignancy. Pre-operative USG findings (TIRADS), presence of lympho-vascular invasion, ETE, capsular involvement, size of the tumor in the ipsilateral lobe and sentinel level VI lymph node biopsy positivity couldn’t significantly predict contralateral disease. Bilateral disease was also found not to be influenced by histology of the tumor although both cases of medullary carcinoma were found to have contralateral lobe involvement with bilateral nodal positivity. Similarly TIRADS 4 and 5 scoring of isilateral lobe were associated with malignancy in contralateral lobe in 63% (12 of 19) of cases (Table 3).
To assess the independence of this correlation and to control for the possible impact of the other studied features on the presence of bilateral disease in well-differentiated thyroidcancers, a binary logistic regression was done using the following variables: age over 55, female gender, histology, size of the tumor, lympho-vascular invasion, lymphnode involvement, extra-thyroidal extension, tumor capsule involvement and multifocality. (Table 4) Again multifocality in the initial ipsilateral lobe was found to be the only significant predictor of bilateral malignancy [OR = 5.53, 95% CI 1.01–30.35, p = 0.048] (Table 4).
Table 4.
Odds ratios of probable predictors of bilateral disease following binary logistic regression in well differentiated cancers
| N = 40 | Odds ratio | 95% confidence interval | P value |
|---|---|---|---|
| Age > 55 | 0.96 | 0.27–3.36 | 0.94 |
| Female | 0.68 | 0.14–3.34 | 0.63 |
| Multifocality | 5.53 | 1.01–30.35 | 0.048 |
| Lympho-vascular invasion | 1.26 | 0.19–8.52 | 0.81 |
| Extra-thyroidal extension | 1.79 | 0.15–21.54 | 0.65 |
| Capsular involvement | 0.84 | 0.1–6.67 | 0.87 |
| Lymph node involvement | 1.21 | 0.31–4.76 | 0.78 |
| Size of tumor | 0.87 | 0.5–1.54 | 0.64 |
| Histology | 1.16 | 0.39–3.46 | 0.78 |
The differences which is statistically significant is shown in bold
Complications
3 patients (7.5%) developed permanent unilateral recurrent laryngeal nerve (RLN) palsy of whom 2 were following ipsilateral hemithyroidectomy and only 1 (2.5%) following completion thyroidectomy. Post-operative hypoparathyroidism was observed in 14 (35%) cases following completion thyroidectomy of who 12 were symptomatic after a mean duration of 41.2 (± 6.4) hrs. 4 patients (10%) proceeded to permanent hypoparathyroidism (Table 5). There were no cases of hematoma or seroma meriting re-exploration.
Table 5.
Complications following initial and completion thyroidectomy
| Following primary surgery | Following completion surgery | Total (N = 40) | |
|---|---|---|---|
| Bilateral permanent RLN injury | 0 | 0 | 0 |
| Unilateral permanent RLN injury | 2 | 1 | 3 (7.5%) |
| Temporary hypoparathyroidism | 0 | 14 | 14 (35%) |
| Permanent hypoparathyroidism | 0 | 4 | 4 (10%) |
| Hematoma/Seroma | 0 | 0 | 0 |
Discussion
In the present study, the rate of malignancy in the contralateral lobe in patients undergoing CT for FNAC misdiagnosed thyroid malignancies was 55%.Histologically 81.8% of the tumors in the contralateral lobe were papillary carcinoma. Regarding various variables examined, only multifocality in the ipsilateral lobe of initial surgery was a significant predictor of well differentiated thyroid malignancy in contralateral lobe [OR = 5.53, 95% CI 1.01–30.35, p = 0.048]. The incidence of contralateral malignancy following CT, across previous literatures, varies from 29 to 56.3% [12, 17–22] (Table 6).
Table 6.
Literature review of features predicting contralateral disease in well differentiated thyroid cancers
| Pasieka et al. 1992 [12] N = 60 | Kawaura et al. 2001 [17] N = 128 | Pacini et al. 2001 [18] N = 182 | Alzahrani et al. 2002 [19] N = 101 | Kim et al. 2004 [20] N = 81 | Grigsby et al. 2006 [21] N = 150 | Pitt et al. 2009 [22] N = 228** | Ibrahim et al. 2015 [15] N = 97 | |
|---|---|---|---|---|---|---|---|---|
| Malignancy on completion | 53% | 56.3% | 44% | 51.5% | 36% | 41% | 29% | 48% |
| Multifocality |
88% (n = 14/16) p < 0.001 |
76.6% (n = 36/47) p > 0.05 |
NC |
53.5% (n = 15/28) p = 0.045 |
69% (n = 20/29) p < 0.001 |
– |
45% (n = 9/20) p = 0.02 |
60% (n = 28/47) p = 0.01 |
| Size of tumor | NC | NC | NC | NC | NC | NC | NC | NC |
| Lymph node involvement | NC |
76.5% (n = 13/17) p > 0.05 |
73.3.% (n = 11/15) p = 0.03 |
– | NC | NC | NC | NC |
| Age | – | NC | NC | 60.9% (n = 14/23)* | NC | NC | – | NC |
| Gender | – | NC | NC | NC | NC | – | NC | |
| Thyroiditis | – | NC | – | – | – | – | – | – |
| Exposure to ionizing radiation | – |
100% (n = 6/6) p > 0.05 |
– | – | – | – | – | – |
| Low vs high risk | – | – | NC | – | – | NC | – | NC |
|
Histopathologic Diagnosis |
NC | – | NC | – | NC | – | – | NC |
| Coexistent Benign nodule | – | – | – | – | NC | – | NC | – |
| Extrathyroidal Extension | – | NC | – |
61.5% (n = 16/26)* p = 0.01 |
NC | – | NC | NC |
| Serum Tg > 20 ng/ml | – | – | – |
56.7% (n = 17/30) p = 0.026 |
– | – | – | – |
| PC variant | – | NC (Tall cell) | – | – | – | NC (Follicular) | NC (Follicular) | NC |
| Soft tissue invasion | – | – | – | – | – | NC | – | – |
| Vascular invasion | – | – | – | – | – | NC | NC | NC |
| Resection margins | – | – | – | – | – | NC | NC | NC |
| Tumor capsular invasion | – | – | – | – | – | – | NC | NC |
–Feature not studied, NC = No statistically significant correlation
*Predictive of cervical lymph node metastasis only
**Pitt et al. [16]: the study of factors predicting contralateral disease is limited to PMC (< 1 cm) n = 70
Our study further demonstrates that size of the intra-thyroidal tumor doesn’t significantly correlate to presence of contralateral malignancy. 54.5% of bilateral thyroid malignancies were in fact microcarcinomas (< 1 cm). Mantinan et al. studied incidentally found papillary microcarcinoma (PMC) during thyroid surgery in 91 patients for an average of 10 years to identify predictors of outcomes of incidental PMC. The only independent predictor of recurrence identified in that series was multifocality [23]. These findings are in line with ATA guidelines which recommend completion thyroidectomy to all patients with thyroid cancer unless the tumor is (1) < 1 cm in size, (2) unifocal, (3) intra-thyroidal, (4) node negative, (5) low risk tumor with particular emphasis on that all the above 5 variables are to be met simultaneously in order to decide not to proceed with CT [16]. This further emphasizes on the fact that multifocality rather than size is important in deciding to proceed for CT.
Baloch et al. [24] conducted cross sectional descriptive study involving 57 patients who underwent CT for the treatment of well differentiated thyroid carcinoma and reported a prevalence rate of 50.87% of malignancy in contralateral lobe. They concluded that middle age (30–49 years) and initial diagnosis of papillary carcinoma were the predictor of malignancy in contralateral lobe. The histopathological (multifocality) and USG finding of initial lobectomy/hemithyroidectomy were not considered for calculating the prevalence of malignancy in CL.
Kim et al. [20] analyse the clinical parameter and pathological findings in the ipsilateral lobe of 81 patients undergoing CT to Analyze the factors predicting the presence of cancer in the contralateral lobe. The reported prevalence of malignancy in CL in their series was 35.8%. They concluded that age, sex, size of pathologic type of the primary tumor was not associated with presence of malignancy in CL but the only predictor for the presence of malignancy in the contralateral lobe was multi-focality of cancer in the ipsilateral lobe.
Ibrahim et al. [15] reported a prevalence rate of 48% of malignancy in the contralateral lobe and concluded that multifocality and presence of aggressive subtype of papillary carcinoma in the initial specimen were predictor of bilateral disease than presence of positive cervical nodes, extrathyroidal extension, size and angioinvasion.
We do not perform an intra-operative frozen section as this had not proved beneficial in our previous thyroidectomies and several studies have proved its lack of clinical usefulness in decision making regarding extent of surgery [25–27].
Pacini et al. [18] in a cohort of 182 patients, found that 73.3% of patients with cervical lymph node involvement at the initial surgery had bilateral malignancy. Although it is well established that in the presence of involved cervical lymph nodes a total thyroidectomy is warranted to help with radioactive iodine treatment and further follow-up [16], but in the absence of pre-operative radiologically significant lymph nodes and a benign FNAC report, routine lymph node biopsy and the decision to proceed to total thyroidectomy becomes difficult.
Histological type of cancer was also not found to be significantly predicting bilateral disease. Among papillary carcinomas, we did not have any high risk variants i.e. tall cell, hobnail, diffuse sclerosing types, in our study. However both cases of medullary carcinoma were found to have bilateral disease. ATA does recommend completion thyroidectomy in medullary carcinomas particularly if multifocal [16].
Preoperative USG findings of ipsilateral lobe (normal contralateral lobe or benign nodules in the same) were also found not to significantly predict hidden disease in the contralateral lobe. However, TIRADS 4 and 5 were associated with contralateral malignancy in 63% (12 of 19) of cases (Table 3).
Complications encountered include unilateral recurrent laryngeal nerve palsy in 3 (7.5%) of cases, although only one occurred post completion thyroidectomy. This is slightly higher than previous literature [2, 12, 13, 28]. However we had higher rates of temporary hypoparathyroidism i.e. 14 cases (35%) as compared to previous literature [2, 12, 13]. This probably is due to the inherently low pre-operative calcium levels in almost all our cases. Four cases (10%) did proceed to permanent hypoparathyroidism. Two cases of RLN palsy and 3 of permanent hypoparathyroidism were operated earlier in this study period, which indicates that rate of complications decrease with experience and expertise.
Finally our study has the shortcoming of a small sample size and a possibility of selection bias which was addressed with multivariate logistic regression.
The present study is different from few reported similar studies in the following ways: (i) we have studied and included pre-operative USG findings and TIRADS scoring of ipsilateral lobe as a possible predictor of contralateral malignancy. This has not been studied and mentioned in any of the previous articles. TIRADS score ≥ 4 of ipsilateral lobe has been mentioned as a possible predictor of contralateral malignancy (although not statistically significant). (ii) We analyzed the complications of CT and our study establishes the safety of CT. (iii) Two cases of medullary carcinoma was included in our study and both of them had bilateral disease with bilateral nodal metastases. Hence, it may be suggested that all patient with medullary carcinoma in the initial specimen should undergo CT. (iv) The 8th edition American Joint Cancer Committee (AJCC) staging system was used for staging and analyzing data like cut off age (55 years) and extra-thyroid extension in contrast to the previously reported studies. (v) This is probably the first study reporting on this topic on eastern Indian population as per our search.
Conclusion
Our study shows that the rate of malignancy in contralateral lobe following CT in FNAC misdiagnosed well differentiated thyroid cancers is 55%. Multifocality in ipsilateral lobe was associated with higher risk of malignancy in the contralateral lobe. Preoperative USG findings of ipsilateral lobe could not predict hidden disease in the contralateral lobe but pre-operative USG TIRADS score ≥ 4 of ipsilateral lobe was frequently associated (63%) with bilateral malignancy. CT can be safely performed with minimal additional complications.
Funding
None.
Compliance with Ethical Standards
Conflict of interest
The authors declare that they have no conflict of interest.
Research Involving Human Participants and/or Animals
The study was approved by our institutional ethics committee.
Informed Consent
Informed consent was obtained from all individual participants included in the study for publication of the data in journals.
Footnotes
Publisher's Note
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