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ORIGINAL ARTICLE
Year : 2017  |  Volume : 13  |  Issue : 3  |  Page : 451-455

Diagnostic accuracy of fine-needle aspiration cytology of thyroid gland lesions: A study of 200 cases in Himalayan belt


1 Department of Pathology, Indira Gandhi Medical College, Shimla, Himachal Pradesh, India
2 Department of ENT, Indira Gandhi Medical College, Shimla, Himachal Pradesh, India
3 Department of Surgery, Indira Gandhi Medical College, Shimla, Himachal Pradesh, India

Date of Web Publication31-Aug-2017

Correspondence Address:
Reetika Sharma
Department of Pathology, Indira Gandhi Medical College, Shimla - 171 001, Himachal Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0973-1482.164702

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 > Abstract 

Aims: The study is undertaken to correlate the fine-needle aspiration cytology (FNAC) findings with histopathology in a spectrum of thyroid lesions and to find the diagnostic accuracy of fine-needle aspiration (FNA) so that unnecessary thyroidectomies can be avoided in benign lesions.
Materials and Methods: This study was carried out over the period of 1-year (May 1, 2012–April, 30 2013). FNA specimens obtained from 200 patients were analyzed. Of these, only 40 patients underwent surgery and their thyroid specimens were subjected to histopathological examination.
Results: The age of the patients ranged from 9 to 82 years with mean age being 43 years. There was female preponderance, with male to female ratio being 1:7. On cytology out of 200 cases, 148 (74%) were benign, 25 (12.5%) were malignant, 16 (8%) were indeterminate, and 11 (5.5%) were nondiagnostic. Only 40 patients underwent surgery. On histopathology, 21 (52.5%) cases were benign and 19 (47.5%) were malignant. The statistical analysis of cytohistological correlation for both benign and malignant lesions revealed sensitivity, specificity, and diagnostic accuracy of 84%, 100% and 90%, respectively.
Conclusion: FNAC is a minimally invasive, highly accurate and cost-effective procedure for the assessment of patients with thyroid lesions and has high -sensitivity and specificity. It acts as a good screening test and avoids unnecessary thyroidectomies.

Keywords: Cytohistological correlation, diagnostic accuracy, fine-needle aspiration cytology, thyroid lesions


How to cite this article:
Sharma R, Verma N, Kaushal V, Sharma DR, Sharma D. Diagnostic accuracy of fine-needle aspiration cytology of thyroid gland lesions: A study of 200 cases in Himalayan belt. J Can Res Ther 2017;13:451-5

How to cite this URL:
Sharma R, Verma N, Kaushal V, Sharma DR, Sharma D. Diagnostic accuracy of fine-needle aspiration cytology of thyroid gland lesions: A study of 200 cases in Himalayan belt. J Can Res Ther [serial online] 2017 [cited 2020 Jun 4];13:451-5. Available from: http://www.cancerjournal.net/text.asp?2017/13/3/451/164702


 > Introduction Top


Thyroid lesions are of great importance because most are amenable to medical or surgical management. The differential diagnosis of thyroid lesions is crucial as malignancy necessitates surgery while follow-up is necessary in case of benign lesions.[1] The prevalence of palpable thyroid nodules increases with age and is 4–7% in a middle-aged population.[2] The annual incidence of thyroid carcinoma is 1–2/100,000 population which accounts for 90% of malignancies of the entire endocrine system, 1% of total human malignancies, and 0.5% of total deaths from malignancies.[3],[4]

Fine-needle aspiration (FNA) for cytology evaluation of thyroid cancer was originally used by Martin and Ellis at New York Memorial Hospital in 1930.[5] It is considered to be the “gold” standard in management of patients with thyroid nodules. The routine use of fine-needle aspiration cytology (FNAC) in the assessment of thyroid nodules has reduced the number of patients subjected to thyroidectomy for benign diseases of the thyroid.[6] As a result, the incidence of malignancy in thyroidectomy specimens has increased from 5–10% to 30–50% in the recent years.[7] This relatively simple procedure has assumed a dominant role in determining the management of patients with thyroid nodules.

The study is undertaken to correlate the FNA findings with histopathology in a spectrum of thyroid lesions and to find the diagnostic accuracy of FNA so that unnecessary thyroidectomies can be avoided in benign lesions.


 > Materials and Methods Top


Two hundred indoor/outdoor patients presenting with thyroid swelling in the Department of Surgery and ENT over the period of 1-year, (May 1, 2012 to April 30, 2013) were included in the study. Prior to aspiration, physical examination was carried out to note the mobility of thyroid during swallowing and the presence of enlarged cervical lymph node. The patients were made to lie supine with their neck stretched up. A 23-gauge needle was attached to Franzen's handle with 20 ml disposable syringe. The slides were stained with May-Grunwald-Giemsa (MGG). Of 200 cases, cytohistological correlation was made in only 40 cases. For tissue sections hematoxyline, and eosin (H and E) was used.


 > Observation and Results Top


The age of the patients ranged from 9 to 82 years with the mean age being 43 years. Maximum number of patients (49.5%) were seen in age group of 30–49 years. There was preponderance of female patients, with male to female ratio of 1:7. The common presenting complaint (99.5%) was swelling in thyroid region and associated pain, and discomfort was present in few cases. 78% presented with symptoms of <1-year duration and 4% with duration of more than 5 years. The largest swelling measured 10 cm × 8 cm, and the smallest was 1 cm × 1 cm. Local examination revealed diffuse thyroid swelling in 38.5% and nodular swelling in 61.5% cases, of which most of them had single nodule. The swelling was mobile and firm in majority (98.5%) of cases. Associated cervical lymphadenopathy present in 9 (4.5%) patients.

On cytology out of 200 cases, 148 (74%) cases were benign, 25 (12.5%) were malignant, 16 (8%) were indeterminate, and 11 (5.5%) were nondiagnostic. Cytological spectrum of 148 benign lesions revealed 106 cases of colloid/nodular goiter and 42 cases of thyroiditis (39 autoimmune thyroiditis, 2 subacute thyroiditis, and 1 tubercular thyroiditis) [Figure 1]. Similarly, out of 25 malignant cases, 17 cases were reported as papillary carcinoma, 4 were medullary carcinoma, 3 were anaplastic carcinoma, and 1 was non-Hodgkin lymphomas (NHL) [Figure 2]. Of 16 cases of indeterminate group, 6 were follicular neoplasms [Figure 2]b; and hurthle cell neoplasms and suspicious for papillary carcinoma each constituted 5 cases. Only 11 cases were placed in nondiagnostic category due to repeated hemorrhagic aspirate, thick smears, poorly preserved cell morphology, and inadequate number of follicular cells [Table 1].
Figure 1: (a) Colloid goiter (MGG, ×100). (b and c) Hashimoto thyroiditis-hurthle cell and granuloma (MGG, ×100). (d) Tubercular thyroiditis-follicular epithelial cells with necrosis (MGG, ×100). Inset-Tubercular Bacilli (Ziehl Neelsen, ×1000)

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Figure 2: (a) Papillary carcinoma – Papillae, psammoma bodies (MGG, ×400). (b) Follicular neoplasm (MGG, ×100). (c) Anaplastic carcinoma - pleomorphic cells with prominent nucleoli (MGG, ×400). (d) Non-Hodgkin lymphomas – monomorphic lymphoid cell with lymphoglandular bodies (MGG, ×400)

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Table 1: Spectrum of lesions on FNAC

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Histopathological correlation was made only in 40 out of 200 cases; (subtotal thyroidectomy/total thyroidectomy). Of 40 cases, 21 (52.5%) cases were reported as benign while 19 (47.5%) were reported as malignant. The benign lesions (21) comprised nodular goiter (15), follicular adenoma (4), and hurthle cell adenoma (2) [Figure 3]. In malignant lesions, 13 were diagnosed as papillary carcinoma, 2 were medullary carcinoma and 1 each as follicular carcinoma, hurthle cell carcinoma, anaplastic carcinoma and NHL [Table 2] and [Figure 4].
Figure 3: (a) Multinodular goiter (H and E, ×100). (b) Lymphocytic thyroiditis – destruction of follicles (H and E, ×100). (c) Hurthle cell adenoma – hurthle cells (H and E, ×400). (d) Follicular carcinoma-capsular invasion (H and E, ×100)

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Figure 4: (a) Papillary carcinoma (H and E, ×100). (b) Medullary carcinoma – focus of amyloid (H and E, ×100). (c) Non-Hodgkin lymphomas – intermediate sized lymphoid cells and scant cytoplasm (H and E, ×400). (d) Anaplastic carcinoma-highly pleomorphic cells with prominent nucleoli (H and E, ×400), inset – infarction in the center (H and E, ×40)

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Table 2: Spectrum of lesions on histopathology (n=40)

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Cytohistological correlation of nonneoplastic (19) revealed that out of 18 cases diagnosed as colloid/nodular goiter on cytology, 15 were confirmed on histopathology, while 2 cases turned out to be papillary carcinoma and 1 as paucicellular variant of anaplastic carcinoma along with gaiter. One case was of Hashimoto thyroiditis on cytology, turned out to be papillary carcinoma with features of thyroiditis in adjacent thyroid parenchyma on histopathology. Thus out of 19 cases, 15 were true negative and 4 were false negative [Table 3].


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Similarly, cytohistological correlation of neoplastic lesions revealed that out of 21 cases which were reported as neoplastic on cytology, 9 of these were papillary carcinoma, 3 follicular adenoma, 1 follicular carcinoma, 2 hurthle cell adenoma, 1 hurthle cell carcinoma, 2 medullary carcinoma, and 1 was NHL. Two cases suspicious for papillary carcinoma were confirmed on histopathology. Thus out of 21 cases reported as neoplastic on cytology all were true positives [Table 4].{Table 4}

Statistical analysis

Sensitivity - Likelihood that the patient with disease has positive test results



Specificity - Likelihood that the patient without disease has negative test results





Hence, the sensitivity, specificity, and accuracy in our study came out as 84%, 100%, and 90%, respectively.


 > Discussion Top


In thyroid, prior awareness of nature of disease alters the treatment choice significantly because benign nodules require partial thyroidectomy or lobectomy whereas malignant nodules require widespread surgery, that is, total thyroidectomy, neck dissection followed by radioiodine ablation, and thyroxine supplement throughout life. In thyroid disease early diagnosis of lesion is established by FNAC which is a well-known recognized procedure for preoperative assessment of thyroid nodules.[8]

In the present study, the duration of symptoms was <1-year in 78% cases, whereas in other studies the duration was more than 1-year in their study population.[6],[9] The less duration of symptoms in our study could be due to obvious location of the swelling which might have attracted their attention to seek medical advice and the study was done in hilly region where soil is deficient of iodine constantly. The percentage of malignant cases on cytology in our study was higher as compared to the study by other authors.[6],[8] The possible reason for this could be that most of our patients were from rural population and they were ignorant of the grave consequences of leaving the nodules unattended.

One case (13-year-old child) was diagnosed as tubercular thyroiditis. This patient was a known case of miliary tuberculosis who had diffuse thyroid swelling. In disseminated miliary tuberculosis, it is common for an occasional tubercle to occur within the gland.[10] Thyroid aspirate revealed extensive caseous necrosis along with few follicular epithelial cells. Acid-fast bacilli were positive on Ziehl Neelsen staining. Repeat aspirate was sent for microbiological culture which grew Mycobacterium tuberculosis.

On cytology of 11 (5.5%) patients with indeterminate lesions, follicular neoplasms, and hurthle cell neoplasms were diagnosed in 3% and 2.5% patients, respectively.

Hurthle cell proliferation can be seen in hurthle cell nodule in Hashimoto thyroiditis, hurthle cell adenoma, hurthle cell carcinoma, papillary carcinoma (oncocytic variant), and medullary carcinoma. A helpful feature in the distinction of nonneoplastic from neoplastic hurthle cell lesions is the rarity of dissociated pattern in former.[11] Hurthle cell change occurring in papillary carcinoma can be distinguished from hurthle cell neoplasm by characteristic nuclear features in the former.[12] The oncocytic variant of medullary carcinoma thyroid (MCT), may be difficult to distinguish from hurthle cell tumors but MCT characteristically shows a wide range of cell size, eccentric nuclei, occasional bi, and trinucleate cells with admixture of spindle cells.[11]

Only one patient, 60-year-old male, was diagnosed as NHL (primary). Clinical and radiological investigations did not show any evidence of lymphadenopathy. Primary lymphoma is an uncommon malignancy of the thyroid, comprising from 0.6% to 5% of thyroid cancers in most series.[13] The differential diagnosis includes small cell variant of medullary carcinoma and insular carcinoma. Immunohistochemistry (CD-45 and B-cell markers) is required to confirm the diagnosis.[10]

FNAC sensitivity ranges from 80% to 98% and specificity from 58% to 100%.[6] The overall sensitivity, specificity, and accuracy in our study was 84%, 100%, and 90%, respectively which was comparable to other studies.[6],[14],[15]

The positive predictive value was 100% in our study which was higher as compared to other studies[6],[8],[16] because we did not report even a single case as false positive. The negative predictive value was 78.94% which was lower than other studies[6],[8],[16] because there were four false negative cases in our study.

Of 40 cases, we found discrepancy in only three cases. In first case, the cytological findings were suggestive of nodular colloid goiter. Histopathological examination (HPE) of this case revealed a focus of papillary carcinoma in multinodular goiter. The cause of detection failure was the presence of microscopic focus of papillary carcinoma of thyroid that was missed during aspiration. In second case, the cytological findings were suggestive of Hashimoto thyroiditis which was diagnosed as papillary carcinoma associated with thyroiditis on HPE. The cause of detection failure was that the needle might not had hit the focus of carcinoma. In third case FNAC findings were suggestive of colloid goiter and on histopathology it was diagnosed as paucicellular variant of anaplastic carcinoma after extensive sampling of the specimen. In this case, there was history of progressive increase in thyroid swelling since 1-month. On cytology the malignant cells could not be aspirated due to extensive sclerosis and paucicellularity of the neoplastic cells or missing the lesion altogether.

Anaplastic thyroid carcinomas usually pose no problems on histology because of the obvious invasive growth, high cellularity, and frank anaplasia diagnosis because of the obvious invasive growth, high cellularity, and frank anaplasia. The pauci cellular variant of anaplastic carcinoma is an infrequent type of thyroid tumor. It is important to recognize this variant so as not to be mistaken for Riedel's thyroiditis, which is a reactive condition with a very favorable prognosis. The features which favor paucicellular variant are: Presence of infarction, atypical cells in at least some areas, atypical spindle cells obliterating large blood vessels, and history of recent increase in size of nodule.[17] Lack of correlation of FNA findings with ultrasound was the main drawback and cause of pitfall in our study. In these cases, if we would have done ultrasonography correlation, it could have avoided false negative results. In addition a good clinical details and aspiration at different sites can avoid false negative rate.

FNAC is now considered as the diagnostic test of choice for the preoperative evaluation of thyroid lesions and selection of patients for thyroid surgery. It is a simple, inexpensive, safe, rapid, minimally invasive, and can be carried out in outdoor patients with excellent patient compliance and considered to have a high sensitivity and specificity. However, it has some limitations in specimen adequacy, sampling technique, skill, and experience of pathologist and inability to distinguish follicular lesions reliably, which includes hyperplastic nodule in goiter, follicular neoplasms and papillary carcinoma (follicular variant). It is rarely associated with complications such as hematoma, massive intrathyroid hemorrhage, necrosis, and local metastasis of malignancy from needle track seeding.


 > Conclusion Top


The assessment of patients with thyroid nodules include triple modalities of clinical examination, FNAC and radiologic investigations but thyroid FNA is simple, safe, reliable, and remains a powerful diagnostic tool for thyroid lesions. Indeterminate FNA results and cytodiagnostic errors are unavoidable due to overlapping cytologic features particularly among hyperplastic adenomatous nodule, follicular neoplasms, and follicular variant of papillary carcinoma. Thyroid FNA has high sensitivity and specificity, and act as a good screening test to avoid unnecessary thyroidectomies.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
 > References Top

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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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