Accuracy of Fine Needle Aspiration Cytology of Thyroid Compared to Final Histopathology in Total Thyroidectomy.

Research Article

Austin J Otolaryngol. 2023; 9(1): 1128.

Accuracy of Fine Needle Aspiration Cytology of Thyroid Compared to Final Histopathology in Total Thyroidectomy.

Nasir A Magboul; Waleed Alghamdi*; Khaled Talat; Areej Rajah; Ali AL-Qannass

Department of Otolaryngology, Aseer Central Hospital, Abha, KSA

*Corresponding author: Waleed Alghamdi Otolaryngology Head and Neck surgery unit, Aseer Central Hospital, KSA. Email: wsalghamdi@hotmail.com

Received: March 20, 2023 Accepted: April 28, 2023 Published: May 05, 2023

Background

Thyroid nodules considered as common clinical presentation in head and neck clinic with a prevalence of thyroid nodule ranging from 2%–6% within palpation, 19%–35% using ultrasound imaging, and 8%–65% in autopsy data [1]. Majority of patient presented with thyroid nodule appear to begin with fewer cases of neoplastic disease [2]. Details history and full head and neck examination is important to reach the accurate diagnosis and it must address the risk factor for malignancy like age of the patient, progression of disease and exposure to radiation [3]. A lot of diagnostic modalities have been mentioned in literature like ultrasonography, fine needle aspiration, histopathology, CT scan and even MRI [3].

FNAC become the most important tools in diagnosis of thyroid nodule, its easy office procedure requires no general anesthesia and non-invasive, quick and reliable [3]. The main goal of thyroid Fine-Needle Aspiration (FNA) is to identify the nodules that require surgery and decrease the overall incidence of thyroidectomy among patients with benign disease [4]. However, many studies reported that FNAC has limitations related to specimen adequacy, sampling techniques, and skill of clinician performing the aspiration. In addition to that, it has low accuracy in suspicious cytology and follicular neoplasm. Thus, even if noninvasive techniques such as FNAC can provide an initial diagnosis, histopathological examination of the excised thyroid tissue is required for the final diagnosis [7]. Despite several studies showing a high accuracy with FNAC, emerging studies especially in tropical Africa and other developing countries with a high prevalence of nodular thyroid disease, have shown the accuracy of FNAC to be lower than previously reported and its diagnostic performance has been shown to vary across different studies [8]. So, in our study we wanted to know the accuracy compared to the final histopathology report in our region compared to the actual international percentage to avoid any unnecessary invasive procedure and to improve our accuracy if needed and overcome the false negative and false positive result. Furthermore, we studied the effect of larger thyroid nodule above 4cm to assist the accuracy of FNA as it was more risk for malignancy compared to smaller size [5,6].

Problem Statement: Thyroid nodules are a common clinical problem and they affect about 5% of the World's population. Currently, many diagnostic tests are used to diagnose thyroid swellings with Fine-Needle Aspiration Cytology (FNAC) being the gold standard test, in which it helps in planning extent of surgery. However, in some studies, FNAC has been found to have a low accuracy for malignancy.

Justification: For the past 2 decades, FNAC has become the diagnostic tool of choice for the initial evaluation of thyroid nodules. FNAC is a noninvasive, cost-effective, reliable, and quick to perform procedure in the Out Patient Department (OPD). However, some studies reported that FNAC has many limitations related to specimen adequacy, sampling techniques, and skill of clinician performing the aspiration. So, in our study we wanted to know the accuracy compared to the final histopathology report in our region compared to the actual international percentage to avoid any unnecessary invasive procedure and to improve our accuracy if needed and overcome the false negative and false positive result.

Study Objective: The objective of this study was to evaluate diagnostic accuracy of FNAC in the diagnosis of thyroid nodules and its correlation with histopathological findings at Aseer Central Hospital in Abha, Saudi Arabia.

Hypothesis: It was anticipated that this study will reveal high specificity and low sensitivity of Fine Needle Aspiration Cytology (FNAC) at detecting malignancy in thyroid nodules.

Abbreviations: FNAC: Fine-Needle Aspiration Cytology; FNA: Fine-Needle Aspiration; CT: Computed Tomography; MRI: Magnetic Resonance Imaging; OPD: Outpatient Department; PTC: Papillary Thyroid Cancer; SPSS: Statistical Package for Social Sciences; PPV: Positive Predictive Value; NPV: Negative Predictive Value.

Literature Review

Thyroid nodules are a common clinical presentation. Epidemiological studies show a prevalence of 2%–6% with palpation, 19%–35% using ultrasound imaging, and 8%–65% in autopsy data. The majority of clinically diagnosed thyroid nodules are nonneoplastic and fewer than 5% are malignant and require surgical intervention. There are many risk factors that increase the incident of thyroid nodules such as increasing age, female gender, iodine deficiency, and radiation exposure. [7]

FNAC of the thyroid gland is now a well-established, first-line diagnostic test for the evaluation of diffuse thyroid lesions as well as of thyroid nodules with the main purpose of confirming benign lesions and thereby, reducing unnecessary surgery [9].

Background Routine application of Fine Needle Aspiration Cytology (FNAC) has decreased unnecessary referral of thyroid nodules for surgical treatment and has also increased the cancer rates found in surgery materials. Success of thyroid FNAC depends on skilled aspiration, skilled cytological interpretation and rational analysis of cytological and clinical data. [10]

A study was conducted in Saudi Arabia by Sameer Al-Bahkaly in the year 2020 to correlate the FNAC findings with the histopathology of the excised specimens. It was a retrospective review of 98 patients undergoing thyroidectomy in the Department of ENT, Head and Neck Surgery at King Abdulaziz Medical City in Riyadh, Saudi Arabia. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of FNAC for the diagnosis of solitary thyroid nodules were 55.56%, 88.73%, 65.22%, 84%, and 79.59%, respectively [7].

Another study was done by Robert Masereka in Uganda in the year 2016 to estimate the sensitivity and specificity of FNAC in detecting malignancy for thyroid disease using histopathology as the gold standard. In total, 99 patients were recruited, the F:M ratio was 15.5:1 and median age was 42 years (IQR 34–50). The median duration of symptoms was 364 weeks (IQR 104–986). The proportion of patients with malignancy was 13.3% with papillary thyroid carcinoma being the most predominant type and colloid goiter was the most predominant benign thyroid disease. The sensitivity was 61.5% and specificity 89.5% [8].

Meanwhile in Turkey, Taskin Erkinuresin conducted a study in the year 2020 on the same topic. The sensitivity of thyroid FNAC for malignant cases was 57.89%, specificity was 88.10%, false-positive rate was 11.90%, false-negative rate was 42.11%, positive predictive value was 52.38%, negative predictive value was 90.24% and accuracy rate was 82.52%. "Focus number" variable was detected as the factor that affected the accurate prediction of FNAC and thyroidectomy results by the pathologist [10].

Again, in Saudi Arabia, Hayfa Alolayan conducted a study in the year 2020 to determine the accuracy of FNA in evaluating thyroid nodules to assess the ability of FNA in detecting malignancies of the thyroid gland and to evaluate the role of FNA in the reduction of unnecessary surgeries for the patients with a thyroid nodule. Part of the main results indicated that the accuracy of FNA was 88.6% in diagnosing the Follicular Carcinoma and 90.8% in diagnosing Follicular Adenoma. FNA's overall sensitivity was found to be 91.2%, while the specificity was found at 71.65%. Previous studies placed FNA sensitivity between 89% and 90% [11].

Lastly, a study was done in the UK in the year 2021 by Ahmad K. Abou-Foul on the same topic. The histological reports of 659 consecutive cases of thyroid surgery between 2006 and 2015 were retrieved from our hospital database. Among the 471 patients (71.5%) who underwent preoperative FNAC, the postoperative histology was reported as benign in 352 (74.7%) and malignant in 119 cases (25.3%). Papillary Thyroid Cancer (PTC) was the commonest histological diagnosis. Thy1 grade was reported in 165 (30%) cases, with 19.4% having a final histological diagnosis of malignancy. In the Thy2 group, 85.3% of patients had a benign final histological diagnosis, while 14.7% had malignancy (false-negative results). Malignancy was found in 89% of Thy4 and 100% of Thy5 group patients [12].

Materials and Methods

This retrospective review was carried out among patients undergoing thyroidectomy in the Department of ENT, Head and Neck Surgery at Aseer Central Hospital, Abha, Saudi Arabia. Period of study was from 1-1-2015 to 1-10-2019. All patients’ records during the study period were included in this study (total coverage). Each patient’s data was obtained from electronic records.

Local examination of the swelling and FNAC of thyroid goiters was performed on OPD basis as per standard protocol. Depending on the nature of the goiter as reported in FNAC and depending on the thyroid function status decision was taken regarding the need and extent for surgery. Thyroidectomy specimens preserved in 10% formalin were sent for histopathology examination to the pathology department in our hospital. All FNAC reports were correlated with histopathology diagnosis.

Inclusion Criteria

All patients above the age of 14 presenting with thyroid swellings or referred to the ENT OPD were included in the study.

All patient underwent FNA cytology for thyroid mass then underwent thyroid surgery

Exclusion Criteria

Patients with neck swellings caused by nonthyroidal gland related pathology like lymphadenopathy, branchial cysts, and others were excluded from the study.

Data Collection

Data was collected using data collection sheets including all aspects of the objectives.

Data Analysis

After data were collected, it was modified, coded and entered to statistical software IBM SPSS version 22(SPSS, Inc. Chicago, IL). All statistical analysis was done using two tailed tests. P value less than 0.05 was considered to be statistically significant. Descriptive analysis based on frequency and percent distribution was done for all variables including demographic data, and FNA and histopathological findings. Thyroid profile was described using median value with range due to high variability of measures in relation to nodule nature. Mann-Whitney test was used to compare thyroid profile median value among benign and malignant masses. Cross tabulation was used to test for the distribution of FNA, histopathology and thyroidectomy procedure according to nodule size using exact probability test of significance. FNA diagnostic accuracy was tested using sensitivity (true positive rate), specificity (true negative rate), Positive Predictive Value (PPV), Negative Predictive Value (NPV), and diagnostic accuracy.

Results

A total of 357 patients were included in the study. Patients ages ranged from 18 to 88 years old with mean age of 39.7 11.6 years old. Exact of 299 (83.8%) patients were females. Total thyroidectomy was the surgical procedure among 240 (67.4%) and hemithyroidectomy was the procedure among 116 (32.6%) patients (Table 1).