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Research Article

Thyroid

Tropical Journal of Pathology and Microbiology

2021 Volume 7 Number 2 March-April
Publisherwww.medresearch.in

Fine needle aspiration cytology of thyroid lesions: A single-centre experience

Sheikh S.1, Abbas F.2, Beigh A.3, Farooq S.4*, Latief M.5
DOI: https://doi.org/10.17511/jopm.2021.i02.04

1 Sheema Sheikh, Associate Professor, Department of Pathology, Government Medical College, Srinagar, Jammu and Kashmir, India.

2 Farhat Abbas, Senior Resident, Department of Pathology, Government Medical College, Srinagar, Jammu and Kashmir, India.

3 Ambreen Beigh, Medical officer, Department of pathology, Government Medical College, Srinagar, Jammu and Kashmir, India.

4* Summiya Farooq, Assistant Professor, Department of Pathology, Government Medical College, Srinagar, Jammu and Kashmir, India.

5 Muzamil Latief, Senior Resident, Department of Nephrology, Government Medical College, Srinagar, Jammu and Kashmir, India.

Background FNAC (Fine needle aspiration cytology) is an easy and cost-effective method for the diagnosis of thyroid lesions. The use of the Bethesda system is largely helpful in eliciting the risk of malignancy and helps in further management of patients with thyroid lesions. In this study we studied thyroid lesions and reported them according to the BETHESDA System of Classification based on cytological features on FNAC. Materials and Methods: In this prospective single-centre study conducted over 2 years we included 642 patients with thyroid lesions who underwent FNAC. These lesions were then classified according to the Bethesda system based on cytomorphological features. Results: Out of 642 patients included in our study, 100 were males and 542 were females with a male: female ratio of 1:5.42. The age of the patient population in our study ranged from 4-94 years. Among 642 cases in our study most (61.38%) cases were benign whereas 9.96% cases were found to be malignant and 2.60% cases were suspicious of malignancy. Conclusion: Bethesda System of reporting FNAC of thyroid lesions is a standardized system and helps in deciding diagnostic approach and appropriate management of patients.

Keywords: FNAC, Thyroid, Bethesda system, Cytology

Corresponding Author How to Cite this Article To Browse
Summiya Farooq, Assistant Professor, Department of Pathology, Government Medical College, Srinagar, Jammu and Kashmir, India.
Email: 		Sheikh S, Abbas F, Beigh A, Farooq S, Latief M. Fine needle aspiration cytology of thyroid lesions: A single-centre experience. Trop J Pathol Microbiol. 2021;7(2):85-92.
Available From
https://pathology.medresearch.in/index.php/jopm/article/view/524

Manuscript Received Review Round 1 Review Round 2 Review Round 3 Accepted
2021-03-18 2021-03-28 2021-04-07 2021-04-13
Conflict of Interest Funding Ethical Approval Plagiarism X-checker Note
No Nil Yes 8%

© 2021 by Sheema Sheikh, Farhat Abbas, Ambreen Beigh, Summiya Farooq, Muzamil Latief and Published by Siddharth Health Research and Social Welfare Society. This is an Open Access article licensed under a Creative Commons Attribution 4.0 International License https://creativecommons.org/licenses/by/4.0/ unported [CC BY 4.0].

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Sheikh S. et al: Fine needle aspiration cytology of thyroid

Introduction

Thyroid gland abnormalities are one of the commonly seen pathologies in surgical practice. However accurate diagnosis of thyroid nodules is a challenge for physicians managing patients with thyroid pathologies. Palpable thyroid nodules are more common in women compared to men [1,2]. Thyroid nodules may present with hypothyroidism, hyperthyroidism, cosmetic issues, and problems in other organs including compression of surrounding structures. Some of these lesions have the potential for malignancy [3].

Clinical presentation, hormone levels and imaging are important however, cytological analysis of fine-needle aspiration (FNA) material is the primary modality for initial evaluation of thyroid lesions (1,4-6). Benign lesions require to follow up, while malignant lesions require surgical treatment. FNAC is considered to be the “gold standard” in the selection of patients for surgery [7]. FNAC does not require any previous preparation. It can be performed without local anaesthesia. In medical centres with longstanding experience, diagnostic (adequate) biopsies obtained from solid nodules range from 90–97% [8, 9]. In most clinical settings, the cytology of thyroid nodules is classified into one of six Bethesda categories. [10]

Bethesda categorization is important for cancer risk assessment [11,12] and the preoperative likelihood of low-risk- versus high-risk cancer phenotypes. Furthermore, Bethesda classification may predict high-risk histologic features such as LNM (lymph node metastasis), ETE (extra-thyroidal extension), or lymphovascular invasion (LVI). However, further data are needed to validate such findings [13]. The most common result in thyroid lesions on FNAC is benign cytology which accurately predicts a benign nodule. Three indeterminate groups on cytology show an adequate yet morphologically abnormal sample in which the risk of malignancy is increased though not confirmed.

Such samples are classified as atypia of undetermined significance (AUS), Follicular lesion of undetermined significance (FLUS), suspicious for a follicular neoplasm (FN), or suspicious for malignancy (SUSP). The risk of malignancy is 5–15%, 15–30%, and 60–75% for AUS, FN and SUSP for malignancy respectively [14]. Malignant (M) cytology suggests a highly predictive 97–99% risk of cancer, and thyroidectomy is generally indicated in such cases.

FNAC has undoubtedly improved preoperative risk assessment and provides some information on prognostic indicators according to some studies [15-18].

Materials and Methods

Place of study: GMC Srinagar Kashmir

Type of study: a prospective, observational study

Inclusion criteria: All ages and gender with thyroid nodules or swellings.

Sampling method: fine-needle aspiration cytology(FNAC)

Classification: Bethesda system

This prospective single centre study of thyroid lesions was carried out at the Department of Pathology, Government Medical College, Srinagar which is a tertiary care centre. The study was carried for 2-years from January 2018 to December 2019.

A total of 642 cases of thyroid lesions were included in the study. done during this period. Consent was taken from all patients for the FNAC procedure after informing them about the complications of the procedure. FNAC was performed in all patients presenting with thyroid swellings either blindly or under US(ultrasound) guidance.

Ultrasound guidance was used in cases in which the lesions were either deep-seated, non-palpable or subcentimetric. All cases were diagnosed and classified based on the Bethesda system of classification. In patients with multiple nodules in the same gland, Bethesda classification and analysis were done according to the highest risk thyroid Bethesda system (TBS), as this was most likely to help clinicians to make appropriate decisions.

All FNA was done by the pathologist as the outpatient procedure and ultrasound-guided FNA was done in cases where lesions were non-palpable and deep-seated lesions. Smears prepared were air-dried and stained with May–Grunwald–Giemsa (MGG) and wet smears were stained with Papanicolaou and haematoxylin and eosin stain (H&E).

Stained slides were examined under a light microscope. The results were categorised into Bethesda classification and further subcategorised based on cytological features.

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Results

Table 1: Gender distribution of cases

No of males 100
No of females 542
Total 642

In our study the total number of patients included was 642. Out of these 100 were males and 542 were females as shown in the table above

Male: female ratio was 1:5.42.

The age of patients ranged from 4-94 years. Most of the patients were in the age group of 21 -50 years.

All patients were categorised on the basis of Bethesda system as given in table below

Table 2: Bethesda categorization of patients

BETHESDA CATEGORY NO. OF PATIENTS %age
CATEGORY I NON DIAGNOSTIC 118 18.38
CATEGORY II BENIGN 393 61.21
CATEGORY III AUS 9 1.40
CATEGORY IV FN/SUSP FN 40 6.23
CATEGORY V SUSP OF MALIGNANCY 18 2.80
CATEGORY VI MALIGNANT 64 9.96
AUS; Atypia of undetermined significance; FN Follicular neoplasm; SUSP Suspicious of malignancy; M Malignant

Most of the cases belonged to benign category II (61.21%). Atypia of undetermined significance (category III) was seen in 1.40% of cases.

6.23% cases belonged to Category IV designated as Follicular neoplasm or suspicious of follicular neoplasm. 2.80% cases belonged to category V or were suspicious for malignancy and malignant lesions accounted for 9.96% of all cases.

Bethesda category III which included benign lesions was further subcategorized into colloid /adenomatoid goitre, lymphocytic or Hashimoto's thyroiditis and granulomatous thyroiditis.18.38%cases were non-diagnostic.

Table-3: Age distribution of thyroid lesions

AGE COLLOID GOITRE/ ADENO- MATOID GOITRE LYMPH- OCYTIC THYR-OIDITIS GRANULO- MATOUS THYROIDITIS FOLLICULAR NEOPLASM HURTHLE CELL NEOPLASM PAPILLARY CARCINOMA MEDU- LLARY CA ANAPLASTIC CA METASTASIS
</=10 4 0 0 0 0 0 0    
11-20 15 6 0 3 0 7 0    
21-30 56 29 0 4 0 30 2    
31-40 82 19 4 7 4 12 0    
41-50 70 8 3 4 3 7 0   1
51-60 44 9 2 5 2 3 0    
61-70 28 0 0 4 2 0 1 1  
71-80 10 1 0 0   1 1    
81-90 2 0 0 0          
>90 1 0 0 0          
total 312 72 9 27 13 58 4 1 1

Colloid goitre was seen predominantly in the 31-40 years age group. 43 of 312 patients of colloid goitre were males and 269 patients were females. Lymphocytic thyroiditis was seen in a predominantly 21-30years age group among whom 5 of 72 patients were males and 67 were females. Most patients with granulomatous thyroiditis were in the age group of 31-40. The most common age group for follicular/ hurtle cell neoplasms was 41-50 years among these 10 out of 40 patients were males and 30 were females. Malignant lesions were most predominant in the 31-40 years age group among these 19 of 64 patients were males and 45 were females.

patho_524_01.jpg

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Figure 1: Showing monolayered sheet of follicular cells forming honeycomb in case of a colloid goitre on haematoxylin and eosin staining

patho_524_02.jpg

Figure 2: Hashimoto’s thyroiditis showing hurthle cells in a lymphoid background on MGG staining

patho_524_03.jpg

Figure 3: Epitheloid cell collection in case of granulomatous thyroiditis on MGG staining

Follicular neoplasms were also subcategorized into follicular neoplasms and hurthle cell neoplasms. Also malignant tumors were categorized into subcategories based on cytomorphological features. Sub categorization of various thyroid lesions is shown in table 2 along with age distribution.

patho_524_04.jpg

Figure 4: Papillary carcinoma thyroid: showing nuclear overlapping grooving and intranuclear inclusions.

patho_524_05.jpg

Figure 5: Medullary carcinoma showing dyscohesive cell cluster with plasmacytoid cells on MGG staining

patho_524_06.jpg

Figure 6: Highly pleomorphic cells and mitotic figures in a case of anaplastic carcinoma

Discussion

The Bethesda system has standardized thyroid nodule terminology in cytology. Using this system the prevalence of malignancy could be effectively conveyed to both the patient and the practitioner, for better decision making. Also it has become easy for the pathologist to interpret the cases where a specific pathology cannot be elicited. Therefore, it remains the gold standard for the initial evaluation of thyroid lesions. In our study 642 cases of thyroid lesions were categorised into the Bethesda system and were further subcategorised based on cytological features of FNA Samples.

The age of patients ranged from 4-94 years with most cases in the age range of 31 to 40 (28.34%) followed by 21-30 years (4.92%). Comparable results were found in other studies done previously.

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(19,20,21,22,23) In our study 542 patients were females with a male to female ratio of 1:5.42. The results were similar to a study done by Bhagat et al (20) in which the ratio was 1:5.67 and Kumar et al where the ratio was1:4.4 (24).

Female preponderance in thyroid lesions was seen in other studies done by yang J et al, Bagga PK et al, Rabaglia JL et al and others. (25-32,14)

Majority of patients presented with diffuse swelling similar to the study done by Vasudha et al. (33)

Out of 642 cases 18.38% were non-diagnostic, 61.21% were benign, 1.40% cases showed AUS, 6.23% cases showed follicular neoplasm/FLUS, 2.80% were suspicious of malignancy and 9.96% were malignant as per the Bethesda system. Comparison of patients as per Bethesda category is shown below

Bethesda Category (%) Current Study Prathima et al [34] Bhagat et al [20] Sinna et al [35] Mondak SK al [36]
N (Total Cases) 642 178 172 296 1020
Non diagnostic 18.38 11.7 5.6 7.1 1.2
Benign 61.21 77.5 87.5 33.1 87.5
Atypia of undetermined significance 1.40 1.12 15 13.5 1
Follicular neoplasm /suspicious of follicular neoplasm 6.23 3.9 3.1 16.5 4.2
Suspicious of malignancy 2.80 2.2 0.6 10.1 1.4
Malignant 9.96 3.3 3.1 19.5 4.7

In our study the number of cases in the non-diagnostic category (category I) was more compared to other studies. This could be because of a large number of total cases in our study.

Also the percentage of follicular neoplasms, malignant cases and cases suspicious for malignancy was higher in our study compared to other studies. These differences could be due to a large number of overall cases in our study. In our study the benign lesions which belong to Bethesda category II, were further classified into colloid/adenomatoid goitre, lymphocytic thyroiditis and granulomatous thyroiditis.

Among this most common entity was colloid/adenomatoid goitre accounting for 79.38% cases, followed by lymphocytic thyroiditis accounting for 18.38% and then granulomatous thyroiditis accounted for 2.29% cases of benign lesions.

This distinction of category II cases helped the clinicians to treat these entities better. Similar results were found by Agarwal et al where the commonest pathology was colloid or adenomatoid goitre followed by lymphocytic thyroiditis followed by Hashimoto's thyroiditis, followed by granulomatous thyroiditis. (37) Colloid/adenomatoid goitre was the common disease overall 312/642(48.59%) cases. This is comparable to a study done by Lakshmi et al where nodular goitre was the commonest disease accounting for almost 50.59% of cases. [38]

In our study only 1.40% of cases belonged to category III, due to strict adherence to diagnostic criteria. Similar results were found by Savita S et al. (39) In our study among category IV 27/40(67.5%) cases belonged to follicular neoplasms and 13/40 (32.5%) cases belonged to hurthle cell neoplasms. Malignant cases accounted for 9.96% of our study and cases suspicious for malignancy were 2.80%. This was unlike the studies done by Nandekar et al where malignant cases were 1.98 %. (40) and Mehra et al where the malignant cases were only 2.2%. (41) The commonest malignancy was papillary thyroid carcinoma 58/64(90.625%), followed by medullary carcinoma 4/64(6.25%). We had a single case of anaplastic carcinoma and metastasis to the thyroid each. This was similar to the study done by Lakshmi et al where the commonest malignancy was papillary carcinoma thyroid. [38]

Conclusion

Bethesda system is a reliable system for classifying thyroid lesions. It also provides prognostic information about cancer type, variant, and risk of recurrence. It also gives clear cut guidelines for the surgical management of patients. This study was done to show the distribution of various thyroid lesions in Kashmir valley and the increased prevalence of malignant lesions of thyroid in this part of the world compared to others. Neoplastic lesions of the thyroid designated by category IV V and VI were more common in our study.

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What does this study add to existing knowledge?

Bethesda system provides prognostic information about cancer type, variant, and risk of recurrence. It also gives clear cut guidelines for the surgical management of patients.

Author contributions

SS, FA and SF collected the data and conducted this study. FA and AB did data analysis. ML and FA did manuscript drafting. All authors were involved in revising and approved the final version of the manuscript.

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