Diagnostic accuracy of fine-needle aspiration cytology with histopathology of thyroid swellings in king Abdulaziz Medical City

Sameer Al-Bahkaly; Abdullah Alshamrani; Leen Omar Hijazi; Maysan Mohammed Almegbel; Majed M Pharaon

doi:10.4103/JNSM.JNSM_46_19

ORIGINAL ARTICLE

Year : 2020 | Volume : 3 | Issue : 2 | Page : 121-125

Diagnostic accuracy of fine-needle aspiration cytology with histopathology of thyroid swellings in king Abdulaziz Medical City

Sameer Al-Bahkaly¹, Abdullah Alshamrani², Leen Omar Hijazi³, Maysan Mohammed Almegbel³, Majed M Pharaon³
¹ College of Medicine, King Saud Bin Abdulaziz University for Health Sciences; Department of Surgery, King Abdulaziz Medical City, Riyadh, Saudi Arabia
² College of Medicine, King Saud Bin Abdulaziz University for Health Sciences, Ministry of National Guard –Health Affairs, Riyadh, Saudi Arabia
³ College of Medicine, King Saud Bin Abdulaziz University for Health Sciences, Ministry of National Guard–Health Affairs, Riyadh, Saudi Arabia

Date of Submission	11-Oct-2019
Date of Decision	26-Oct-2019
Date of Acceptance	11-Nov-2019
Date of Web Publication	02-Apr-2020

Correspondence Address:
Sameer Al-Bahkaly
King Saud Bin Abdulaziz University for Health Sciences, Riyadh; Department of Surgery, King Abdulaziz Medical City, Riyadh
Saudi Arabia

Source of Support: None, Conflict of Interest: None

Read associated Erratum: Erratum: Diagnostic accuracy of fine-needle aspiration cytology with histopathology of thyroid swellings in King Abdulaziz Medical City with this article

DOI: 10.4103/JNSM.JNSM_46_19

Abstract

Introduction: Thyroid nodules are a common clinical problem. Currently, many diagnostic tests are used to diagnose thyroid swellings with fine-needle aspiration cytology (FNAC) being the gold standard test. However, FNAC has limitations, and a histopathology report is needed for the final diagnosis. The purpose of this study is to correlate the FNAC findings with the histopathology of the excised specimens. Materials and Methods: This is 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. Period of study was from May 2011 to June 2014. Results: 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. Conclusion: FNA is a simple, safe, and cost-effective diagnostic modality for thyroid carcinoma. It is recommended as the first-line investigation for the diagnosis of solitary thyroid nodule.

Keywords: Fine-needle aspiration cytology, histopathology, thyroid

How to cite this article:
Al-Bahkaly S, Alshamrani A, Hijazi LO, Almegbel MM, Pharaon MM. Diagnostic accuracy of fine-needle aspiration cytology with histopathology of thyroid swellings in king Abdulaziz Medical City. J Nat Sci Med 2020;3:121-5

How to cite this URL:
Al-Bahkaly S, Alshamrani A, Hijazi LO, Almegbel MM, Pharaon MM. Diagnostic accuracy of fine-needle aspiration cytology with histopathology of thyroid swellings in king Abdulaziz Medical City. J Nat Sci Med [serial online] 2020 [cited 2023 Jan 30];3:121-5. Available from: https://www.jnsmonline.org/text.asp?2020/3/2/121/278239

Introduction

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.^[1] The majority of clinically diagnosed thyroid nodules are nonneoplastic and fewer than 5% are malignant and require surgical intervention.^[2] There are many risk factors that increase the incident of thyroid nodules such as increasing age, female gender, iodine deficiency, and radiation exposure.^[1]

Currently, a multitude of diagnostic tests including ultrasound, thyroid nuclear scan, fine needle aspiration cytology (FNAC) as well as histopathological techniques are available for clinicians to evaluate thyroid nodules.^[3] For the past 2 decades, FNAC has become the diagnostic tool of choice for the initial evaluation of thyroid nodules.^[3] It is often used in conjugation with other imaging modalities such as ultrasound or mammogram as guidance to reach the nodule.^[4] FNAC is a noninvasive, cost-effective, reliable, and quick to perform procedure in the outpatient department (OPD).^[4] However, FNAC has many limitations related to specimen adequacy, sampling techniques, and skill of clinician performing the aspiration.^[2] It also has low accuracy in suspicious cytology and follicular neoplasm.^[4] 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.^[2]

Few studies have validated the diagnostic accuracy of FNAC with histopathology of thyroid nodules across Saudi Arabia. Therefore, the aim of the current study is to evaluate diagnostic accuracy of FNAC in the diagnosis of thyroid nodules and its correlation with histopathological findings at King Abdulaziz Medical City in Riyadh, Saudi Arabia.

Materials and Methods

This retrospective review was carried out among patients undergoing thyroidectomy in the Department of ENT, Head and Neck Surgery at King Abdulaziz Medical City in Riyadh, Saudi Arabia. Period of study was from May 2011 to June 2014. Each patient's medical history was obtained from the Quadramed system's database, which contains the patients' 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 12 presenting with thyroid swellings or referred to the ENT OPD were included in the study.

Exclusion criteria

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

Statistical analysis

Data were compiled in MS Excel and analyzed using SPSS version 20 using descriptive statistics. Categorical variables were summarized using frequency tables. Descriptive statistical techniques were carried out to calculate the age, gender, specificity, and sensitivity of the diagnostic test. The FNAC results and histopathology reports were compared, and conclusions were drawn after statistical analysis.

Results

A total of 98 patients who underwent hemi or total thyroidectomy were identified, 16 (16.3%) were males and 82 (83.7%) were females. Age of the patients ranged from 21 to 81 years with mean age of 47.59 years.

The final provisional diagnosis on FNAC was categorized based on Bethesda classification.

Benign
Atypia of undetermined significance
Suspicious for neoplasm
Suspicious of malignancy
Malignant.

[Table 1] shows that 76.5% of the 98 thyroid FNACs were benign, 32.5% of which were nodular goiters and 14.2% were benign follicular adenomatous nodules. Atypia of undetermined origin included seven cases, all of which were follicular lesions of undetermined significance. In the third category, suspicious of neoplasm, all six cases were cytologically diagnosed as follicular neoplasm. The three cases under the suspicious for malignancy category were all suspicious for papillary carcinoma. In the malignancy category, seven cases were identified and were cytologically diagnosed as five cases of papillary carcinoma and a single case of each medullary carcinoma and undifferentiated anaplastic carcinoma.

Table 1: Diagnostic categorization of 98 thyroid fine needle aspiration cytology based on Bathesda classification

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Histopathological findings of excised specimens showed 67 (68%) cases of nonneoplastic swellings which included 10 cases of lymphocytic thyroiditis, 41 cases of nodular goiters, 4 as multinodular goiter with cystic degeneration, 2 nodular hyperplasia with parenchymal hemorrhage, and one benign epithelial cyst. Four cases were reported as neoplastic benign follicular adenoma. Of total 98 cases, 26 (26.8%) were diagnosed as neoplastic malignant, 21 of which were papillary carcinoma, two cases each follicular carcinoma and anaplastic carcinoma and a single case of medullary carcinoma, respectively.

FNAC results were compared with histopathological reports and the findings are summarized in [Table 2]. Sixty-eight of cases were diagnosed as nodular goiters by FNAC, 54 of which were multinodular goiters, 11 were papillary carcinoma, 1 was follicular adenoma and 2 were diagnosed as hashimoto thyroiditis in histopathological examination. One case was diagnosed as thyroglossal cyst on FNAC and as multinodular goiter on histopathology report. Six of the cases were shown to be hashimoto thyroiditis on both FNAC and histopathology reports.

Table 2: Nonneoplastic lesions diagnosed by fine needle aspiration cytology and their comparison with histopathological diagnosis

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[Table 3] shows that 23 cases were diagnosed by FNAC as neoplastic benign or malignant lesions. On histopathology, 8 cases were nonneoplastic and 15 were neoplastic malignant. On FNAC, 13 cases were reported as follicular neoplasm, 7 of which were hyperplastic nodular lesions, 3 were papillary carcinoma, 2 follicular, and one as insular type carcinoma. Three cases were suspicious for papillary carcinoma by FNA Bethesda categorization, but on histopathology, two were found to be positive for papillary carcinoma and one for benign hashimoto's thyroiditis. The rest were diagnosed as malignancy on FNAC and were in fact cancerous as well on histopathology reports.

Table 3: Benign or suspicious/neoplastic lesions diagnosed by fine needle aspiration cytology and their comparison with histopathological diagnosis

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Summary of sensitivity, specificity, accuracy, false-positive, and false-negative results are shown in [Table 4].

Table 4: Diagnostic accuracy for detection of neoplastic lesion by Fine needle aspiration cytology

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Discussion

When it comes to the thyroid nodules, it is vital to differentiate between malignant and benign masses since thyroid swelling is a common presentation in medical practice.^[5] FNA provides an easy, safe and fast way of determining the nature of the swelling and it remains the gold standard test for evaluating thyroid nodules.^[5],[6] Most of patients presenting with thyroid nodules were females as observed in a number of studies and it was also found that the incidence increases with age.^{[3],[4],[5],[6],[7],[8]} Likewise, our patients who underwent thyroidectomy were mostly females constituting 83.7% of the population with a mean age of 47.5 years.

In our study, FNA results demonstrated that 76.5% had a benign/nonmalignant lesion, which is similar to the results of Korah and El-Habashi reporting nonneoplastic lesions to be 69% and another study which reported 70.73% of their FNA results to be benign.^[9],[10] Out of all the nonmalignant lesions in our study, nodular goiter was the most common finding (90.7%) [Figure 1] followed by lymphatic thyroiditis and only one case of thyroglossal duct cyst. Our results were comparable to those for Damle and Daharwal, which showed simple and nodular goiter to be the most common of benign masses.^[3] In addition, another study done in 2008 showed a less percentage of colloid goiters making 57.6% of benign masses, but was still the most observed finding.^[11]

Figure 1: (a) Fine-needle aspiration shows a cluster of unremarkable thyroid follicular cells in a background of colloid (upper left corner) (Diff Quik, ×200). (b) Variably-sized thyroid follicles filled with colloid (H and E, ×40)

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Upon comparing nonneoplastic FNA findings with histopathology results, 80.9% of nodular goiter cases were true negative by histopathology, showing 54 cases to be multinodular goiter and 1 hashimoto's thryroidits, while 17% of cases were false negative showing papillary carcinoma (n = 11) or follicular adenoma (n = 1). Our results showed similarities with the true negative results from Damle and Daharwal, which showed 97.14% of colloid goiter FNA results to be true negative and only one case of papillary carcinoma (2.86% false negative).^[3] Furthermore, in our study 84% of all benign masses on FNA were shown to be true negative; similarly, a study by Mundasad et al. showed 84.2% of nonneoplastic lesions on FNA to be true negative when compared to histopathology findings.^[6]

From our targeted population, 23 FNA samples showed malignant or suspicion of malignancy, 56.5% of which showed follicular or suspicion of follicular neoplasm, the most common, 21.7% showed papillary carcinoma [Figure 2], 13.04% were suspicious of papillary carcinoma, one case of medullary carcinoma and one case showed anaplastic neoplasm (4.34% each). Likewise, both the previously mentioned studies Damle and Daharwal and Wahid et al. showed follicular neoplasm to be the most common finding in FNAC followed by papillary carcinoma as well as a study done by Mehmood et al.^{[3],[10],[12]}

Figure 2: (a) Crowded follicular cells with nuclear overlapping, enlargement, and rare intranuclear pseudoinclusions (arrow) (Diff Quik, ×400). (b) Intranuclear grooves are prominent in this cluster in addition to rare intranuclear pseudoinclusions (arrow) (Pap, ×400). (c) Infiltrative tumor with focal papillary architecture (H and E, ×40). (d) Crowded follicular cells with irregular nuclear borders, intranuclear grooves, and pseudoinclusions (arrow) (H and E, ×400)

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Our results showed 7 out of the 13 cases (53.85%) of follicular carcinoma to be false positive while the remaining 6 were a true positive (46.15%) when compared to histopathology; unlike Damle and Daharwal results, which showed 100% true positive for follicular neoplasia.^[3] In addition, for the FNA results of suspicious of papillary neoplasia, 66.7% (n = 2) were true positive for papillary neoplasia and only one case of false positive which showed hasimoto's thyroiditis on histopathology. Unlike previous discrimination between FNA and histopathology results, all cases of papillary, medullary, and anaplastic carcinomas [Figure 3] were true positive.

Figure 3: (a) Very large cells with bizarre nuclei and dense cytoplasm in a background of tumor diathesis (Diff Quik, ×400). (b) An infiltrative highly cellular tumor with epithelioid and spindle cell morphology (H and E, ×40). (c) Pleomorphic cells with large irregular nuclei, high nuclear to cytoplasmic ratio, and prominent nucleoli. Mitotic figures are easily seen (arrow) (H and E, ×400)

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As explained by Goelner et al., sensitivity and specificity valuation relies on how the suspicious category is treated. To elaborate, the sensitivity of the test will increase if the suspicious FNA results are regarded as positive, while specificity will increase if the suspicious FNA results are regarded as negative.^[13] Our study showed FNA sensitivity to be 55.56%, which is lower than Damle and Daharwal (87.5%), Wahid et al.(88.9%), and Bouvet et al.(93.5%).^{[3],[10],[14]} The specificity of FNA results among the previous studies was variable, showing a specificity of 95.6% Damle and Daharwal, 77.50% Wahid et al., and 75% Bouvet et al.^{[3],[10],[14]} Our study also showed a different value for FNA specificity (88.73%). Furthermore, FNA accuracy in our study was 79.59%, which is similar to Bouvet et al. who found FNA accuracy to be 79.6.^[14] Our positive predictive value was inferior to the finding of the previous studies with a result of 65.22% in contrast to 85.3%, 80%, and 77.78% in Bouvet et al., Wahid et al., and Damle and Daharwal respectively.^{[3],[10],[14]} Our negative predictive value of FNA was 84% which is almost equivalent to Bouvet et al.(88.2%) but lower than Damle and Daharwal.^[3],[14]

Conclusion

FNA is a simple, safe and cost-effective diagnostic modality for thyroid carcinoma. It is recommended as the first line investigation for the diagnosis of solitary thyroid nodule. The results of the current study show that the cytologic examination of palpable thyroid nodules by FNA has low sensitivity. A benign cytology should be viewed carefully as false negative results do occur and such patients should be followed up.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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