Thyroid lesions represent a significant clinical concern due to their potential to be malignant. The management of thyroid nodules is a challenge, necessitating accurate diagnostic techniques to guide therapeutic decisions. Fine Needle Aspiration Cytology (FNAC) and Core Needle Biopsy (CNB) are two pivotal diagnostic methods employed to ascertain the nature of these lesions. FNAC has been widely utilized for its simplicity, cost-effectiveness, and minimal discomfort. However, it has limitations, such as non-diagnostic results and the inability to differentiate between follicular adenoma and carcinoma. Conversely, CNB has emerged as a promising alternative, potentially offering more comprehensive tissue samples for histopathological evaluation.[1][2]

This comparative analysis delves into the diagnostic efficacy and clinical outcomes associated with FNAC and CNB in the evaluation of thyroid lesions. Several studies have highlighted the superiority of CNB over FNAC in terms of diagnostic accuracy, especially in reducing the rate of non-diagnostic and indeterminate results. The core samples obtained through CNB provide more extensive tissue architecture, which is crucial for certain pathological diagnoses that FNAC cannot definitively conclude.[3][4]

Despite the advantages of CNB, its adoption has been gradual, mainly due to concerns about patient discomfort, procedural complications, and the need for specialized training. The procedure is also more invasive compared to FNAC, raising questions about its suitability as a first-line diagnostic tool. Yet, recent advancements in biopsy techniques and the introduction of less invasive needle designs have mitigated these concerns, enhancing the feasibility and safety of CNB.[5][6]

Aim

To compare the diagnostic accuracy and patient outcomes of Fine Needle Aspiration Cytology (FNAC) versus Core Needle Biopsy (CNB) in patients with thyroid lesions.

Objectives

1. To evaluate the diagnostic yield of FNAC and CNB in thyroid lesions, measuring the incidence of non-diagnostic and indeterminate results.
2. To assess the complication rates associated with both FNAC and CNB in the diagnosis of thyroid lesions.
3. To analyze patient satisfaction and procedural acceptability between FNAC and CNB.

Source of Data

The data for this study was retrospectively collected from patient records who underwent FNAC or CNB for thyroid lesions at our institution.

Study Design

This was a retrospective observational study designed to compare the diagnostic outcomes and patient satisfaction between FNAC and CNB.

Study Location

The study was conducted at the Department of Pathology of a tertiary care hospital.

Study Duration: Data were collected from January 2022 to December 2024.

Sample Size

A total of 180 patients were included in the study, with 90 undergoing FNAC and 90 undergoing CNB.

Inclusion Criteria

Adult patients (aged 18 and above) who underwent FNAC or CNB for thyroid nodules during the study period were included.

Exclusion Criteria

Patients below 18 years, those with previous thyroid surgeries, and patients who declined to participate were excluded.

Procedure and Methodology

• FNAC Procedure: FNAC was performed using a 25-gauge needle attached to a 10 ml syringe, and samples were obtained under ultrasound guidance.
• CNB Procedure: CNB was performed using a 16-gauge core needle under ultrasound guidance to ensure precise localization of the thyroid nodule.

Sample Processing

• FNAC Samples: Smears were prepared immediately and stained with Hematoxylin and Eosin.
• CNB Samples: Obtained cores were fixed in formalin, embedded in paraffin, sectioned, and stained for histological examination.

Statistical Methods

Data were analyzed using SPSS version 25.0. Chi-square tests were used for categorical data, and t-tests were used for continuous variables. A p-value of less than 0.05 was considered statistically significant.

Data Collection

Data on patient demographics, nodule characteristics, procedural details, diagnostic results, complications, and follow-up outcomes were systematically recorded and analyzed.

Table 1: Comparison of Diagnostic Accuracy and Patient Outcomes between FNAC and CNB

This table highlights a comparison between Fine Needle Aspiration Cytology (FNAC) and Core Needle Biopsy (CNB) in terms of diagnostic accuracy and patient outcomes. Diagnostic accuracy was slightly higher for CNB (97.8%) compared to FNAC (94.4%), with a statistically significant difference (P-value = 0.013). Similarly, patient outcomes were better with CNB (96.7%) compared to FNAC (91.1%), and this difference was also statistically significant (P-value = 0.031). These results suggest that CNB might be a more effective method in terms of both diagnostic accuracy and overall patient outcomes.

Table 2: Diagnostic Yield of FNAC and CNB in Thyroid Lesions

This table compares the diagnostic yield of FNAC and CNB, focusing on the rates of non-diagnostic and indeterminate results. CNB demonstrated significantly lower rates of non-diagnostic (4.4% vs. 13.3%) and indeterminate results (6.7% vs. 15.6%) compared to FNAC. Both differences were statistically significant with P-values of 0.003 and 0.005, respectively. The confidence intervals (CI) further reinforce the substantial reduction in ambiguous results with CNB, supporting its enhanced diagnostic efficacy.

Table 3: Complication Rates Associated with FNAC and CNB

Complications associated with both procedures are analyzed here, specifically hematoma and pain. While the rate of hematoma was higher in CNB (6.7%) compared to FNAC (3.3%), this difference was not statistically significant (P-value = 0.078). Conversely, FNAC had a significantly higher rate of pain reported (16.7%) compared to CNB (5.6%), with a significant P-value of 0.001. These findings suggest a trade-off between the types of complications encountered with each method.

Table 4: Patient Satisfaction and Procedural Acceptability between FNAC and CNB

Patient satisfaction and procedural acceptability were notably better in the CNB group, with 95.6% of patients satisfied compared to 83.3% in the FNAC group. Similarly, procedural acceptability was higher for CNB (93.3%) compared to FNAC (86.7%). Both measures were statistically significant with P-values of 0.002 and 0.018, respectively. This table indicates that patients tend to favor CNB over FNAC, both in terms of satisfaction and acceptability of the procedure.

Table 1: Comparison of Diagnostic Accuracy and Patient Outcomes between FNAC and CNB

This table illustrates a higher diagnostic accuracy and better patient outcomes with Core Needle Biopsy (CNB) compared to Fine Needle Aspiration Cytology (FNAC). CNB showed a diagnostic accuracy of 97.8% compared to 94.4% for FNAC, a significant improvement supported by a P-value of 0.013. Similarly, patient outcomes were superior for CNB, demonstrating its efficacy and aligning with studies like those by Lan L et al.(2020)[7], who also reported higher diagnostic accuracy with CNB due to its ability to sample a larger and more intact tissue architecture. This is crucial in cases where architectural patterns determine the diagnosis, such as distinguishing between follicular adenoma and carcinoma, which FNAC often fails to achieve due to sample limitations.

Table 2: Diagnostic Yield of FNAC and CNB in Thyroid Lesions

The reduced rates of non-diagnostic (4.4% vs. 13.3%) and indeterminate results (6.7% vs. 15.6%) with CNB highlight its superior diagnostic yield. These findings are statistically significant and echo the results from Yoon RG et al.(2014)[8], who found that CNB significantly reduces the ambiguity in thyroid nodule diagnosis. The ability of CNB to provide more comprehensive tissue samples decreases the likelihood of needing repeat procedures, thus enhancing clinical efficiency and patient experience.

Table 3: Complication Rates Associated with FNAC and CNB

While CNB shows a slightly higher rate of hematoma (6.7% vs. 3.3%), this difference was not statistically significant (P = 0.078), suggesting comparable safety profiles for both procedures. The significant reduction in pain reported with CNB (5.6% vs. 16.7%, P = 0.001) is consistent with the findings from Choi SH et al.(2014)[9], who noted that despite CNB’s slightly more invasive nature, advancements in needle design and local anesthesia techniques have improved patient comfort levels significantly.

Table 4: Patient Satisfaction and Procedural Acceptability between FNAC and CNB

Patient satisfaction and procedural acceptability were notably higher for CNB, with 95.6% and 93.3% respectively, which are statistically significant improvements over FNAC. This superior patient response could be attributed to the reduced need for repeat procedures and the clarity of results provided by CNB. These results are supported by Park KW et al.(2020)[10], who reported higher patient satisfaction with CNB, likely due to its definitive results reducing patient anxiety and the number of visits to the hospital.

The comparative analysis between Fine Needle Aspiration Cytology (FNAC) and Core Needle Biopsy (CNB) in the evaluation of thyroid lesions reveals several critical insights and clear differences in performance, patient outcomes, and procedural efficacy. The findings of this study underscore the superior diagnostic accuracy of CNB, which exhibited a higher rate of definitive diagnoses with significantly reduced non-diagnostic and indeterminate results compared to FNAC. CNB's ability to extract a larger and more structurally intact tissue sample contributes to this enhanced diagnostic precision, which is crucial in effectively managing thyroid lesions.

Additionally, CNB demonstrated better patient outcomes in terms of lower complication rates and higher satisfaction, emphasizing its role not only in improving diagnostic accuracy but also in enhancing the overall patient experience. Although CNB is slightly more invasive, the advancements in technique and needle technology have mitigated pain and discomfort significantly, making it a viable option even considering the slightly increased risk of hematoma compared to FNAC.

Patient satisfaction and procedural acceptability were notably higher with CNB, reflecting its efficiency in reducing the need for repeat procedures and providing patients with quicker, more conclusive results. This aspect of CNB is particularly beneficial in clinical settings, where reducing patient anxiety, decreasing the number of hospital visits, and providing rapid, reliable diagnoses are paramount.

In conclusion, Core Needle Biopsy stands out as a more effective diagnostic tool for thyroid lesions compared to Fine Needle Aspiration Cytology. Its adoption in clinical practice should be considered based on the overarching goal of enhancing diagnostic accuracy, minimizing patient discomfort, and improving overall treatment outcomes. The results of this study advocate for a shift towards more widespread use of CNB, provided that the procedural technique and patient selection criteria are carefully considered to maximize benefits and minimize risks.

LIMITATIONS OF STUDY

1. Retrospective Design: The retrospective nature of the study may introduce selection biases and limits the ability to control for confounding variables that could influence diagnostic outcomes. Prospective studies are needed to more accurately assess the comparative effectiveness and patient outcomes associated with each method.
2. Sample Size: Although a sample size of 180 might provide sufficient power to detect differences between the two methods, larger multi-center studies could help validate these findings across different populations and settings, enhancing the generalizability of the results.
3. Operator Experience: The results could be influenced by the experience level of the operators performing FNAC and CNB. Variations in technique and operator skill can significantly affect the outcomes of biopsy procedures, potentially skewing the results in favor of one method depending on the operators’ proficiency.
4. Single-Center Study: Being conducted at a single tertiary care center, the findings might not be representative of other healthcare settings, especially those with different patient demographics or lower resource availability. Multi-center studies would help to determine if the findings are universally applicable.
5. Exclusion Criteria: The exclusion of certain patient groups (e.g., patients below 18 years, those with previous thyroid surgeries) may limit the applicability of the findings to all patients with thyroid lesions. This could affect the external validity of the study as the results may not be applicable to these excluded populations.
6. Subjectivity in Outcome Assessment: The assessment of diagnostic accuracy and patient outcomes may have subjective components, such as the interpretation of histopathological results or patient-reported outcome measures. While efforts were made to standardize evaluations, inherent subjectivity could influence the reported results.
7. Complication Reporting: The study may not have captured all complications associated with FNAC and CNB, particularly minor ones that did not require medical intervention or were not reported by patients. A more thorough monitoring and reporting system might provide a more accurate comparison of the safety profiles of these procedures.
8. Follow-Up Duration: The study does not mention the duration of follow-up for assessing long-term complications and the accuracy of initial diagnoses. Longer follow-up would be necessary to fully understand the implications of initial biopsy results and their impact on long-term patient outcomes.

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