Discussion
Thyroid nodules exhibiting characteristics such as hardness, fixation or rapid growth necessitate immediate assessment. Studies have established that the specific location of the nodule within the thyroid gland is an independent factor contributing to the risk of malignancy. Nodules originating in the isthmus region have the highest likelihood of malignancy, while those situated in the lower portion of the thyroid lobes have the lowest risk when compared to those in the middle or upper regions (9,10). In the current study, upon examination, it was found that tumors in 35.9% of cases exhibited a firm consistency, while 22.6% were hard and 41.5% were in between. Tumors in only 7.5% of the cases involved the isthmus.
The primary method used for thyroid imaging is U/S. To assess thyroid nodules and preliminarily estimate their potential for malignancy, the radiologist should consider several factors, including hypoechogenicity, infiltrative, lobulated or irregular margins, the presence of microcalcifications and a shape that is taller than it is wide. Alongside evaluating the nodule, U/S examination should comprehensively examine all cervical lymph node areas and any suspicious lymph nodes should be documented (11). The ability to accurately distinguish malignant lesions from benign ones varies among these features, and none of them have consistently provided reliable differentiation between the two (12). In the present study, U/S revealed a solid texture in 39.6% of the cases, with 71.7% categorized as TR3.
In general, FNAC represents the subsequent phase in the evaluation of a thyroid nodule. This procedure should be selectively performed for nodules deemed highly suspicious based on both U/S and clinical assessments. The outcomes of this cytological analysis have a significant role in refining subsequent treatment strategies (13). Nevertheless, various potential diagnostic challenges exist that may result in erroneous outcomes, such as false positives, false negatives, indeterminate findings or non-diagnostic results (14). It is noteworthy that a substantial portion, up to 42%, of cases may fall into the indeterminate category, encompassing both follicular neoplasms and those with suspicious malignancy features (15). The predominant FNAC results among the patients of the present study were Bethesda II in 52.8% of cases and Bethesda IV in 15.1%.
Surgical intervention is a viable option for hyperfunctioning nodules and nodules causing compression, although there are various minimally invasive alternatives. These encompass U/S-guided ablation techniques such as percutaneous ethanol injection, the application of thermal energy in the form of laser, radiofrequency, high-intensity focused US or microwave energy. Radiofrequency and laser ablations have demonstrated notable efficacy in reducing nodule volumes (16). When surgical intervention is deemed necessary, the determination of the appropriate extent of resection is contingent upon several factors. These factors encompass the presence of symptoms, the existence of nodules on the contralateral side, the thyroid's functional status, concurrent medical conditions, familial medical history, surgical risks and the patient's preferences (4). Surgical intervention was warranted in the present cases primarily due to the presence of large nodules in 69.9% of cases, toxic nodules in 15.0% and suspicion of follicular neoplasms in 7.5%.
When malignancy is suspected, the least extensive surgical procedure typically considered is lobectomy along with isthmusectomy. In rare instances, isthmusectomy alone could also be considered (4). Certain studies suggest the use of minimally invasive US-guided ablation methods as an alternative to surgery for managing small nodules that raise suspicion (17). Advancements in surgical technology, including thermal sealing, have led to substantial modifications in surgical procedures. These advancements enable the safe removal of nodules along with an appropriate margin of healthy tissue for diagnostic purposes in a bloodless manner, without the requirement for extensive manipulation and ligation of major blood vessels (5). Recent research has revealed that the size of the thyroid remnant volume can impact the occurrence of postoperative hypothyroidism (18). In their study involving 186 patients who underwent unilateral lobectomy, De Carlucci et al (18) and others discovered that the occurrence of hypothyroidism was 6.3 times higher when the US-measured volume of the thyroid remnant was 4 ml or less (19).
It has been shown that the absence of hypoechogenic attenuation, irregular margins, or microcalcifications as identified through U/S holds a notably high negative predictive value for excluding malignancy in Bethesda Ⅲ nodules. Consequently, in such cases, nodulectomy emerges as an appealing option (20). Findings from a particular study have shown that when undertaken for the specified indications, minimally invasive thyroid nodulectomy results in a notable reduction in the post-operative risk of hypothyroidism in comparison to both formal open lobectomy and minimally invasive lobectomy (5). In the current study, there was no reported case of hypothyroidism following the surgery and there was only one case of seroma as a complication of the procedure. Seroma formation is frequently associated with procedures such as mastectomy, laparoscopic inguinal hernia repair, axillary lymphadenectomy and abdominoplasty. However, it is less commonly reported following thyroid surgery, with an incidence ranging from 1.3 to 7%. In the majority of cases, seromas resolve spontaneously and do not require intervention (21). Histopathological examination revealed three cases of minimally invasive follicular thyroid carcinoma and four cases of minimally invasive papillary thyroid microcarcinoma. All of these cases underwent total thyroidectomy. Due to limited data on nodulectomy being available, it was not possible to further compare nodulectomy with lobectomy and other procedures.
Different surgical techniques have different purposes and are appropriate in certain situations; understanding these distinctions is critical for both patients and healthcare practitioners. Nodulectomy may reduce the probability of postoperative hypothyroidism by maintaining a significant portion of the thyroid gland (5). This procedure may typically demand less time in comparison to total thyroidectomy or lobectomy. It may carry a low likelihood of complications, including RLN injury and parathyroid gland damage, when compared with more extensive surgical interventions. The present study has several limitations. These include the small sample size, short follow-up duration and reliance on data from a single center, which limit the generalizability of the results. Future studies with a sufficient sample size and robust study design are required to better evaluate this procedure and compare it with other available management techniques.
In conclusion, nodulectomy may be a suitable choice for managing benign large nodules, small suspicious nodules or microcarcinomas, and for situations where preserving thyroid function is paramount. However, the definitive outcome of the procedure requires much more intensive investigation. It needs to be compared in clinical trials with other management techniques such as lobectomy, isthmusectomy or U/S-guided ablation methods.