European Journal of Cardiovascular Medicine

Among all the endocrine disorders, thyroid disorders are the most frequent in India and thyroid swellings are the common presentation in clinical practice.¹ Most of the thyroid swellings are benign and benign neoplasms out number thyroid carcinomas by a ratio of nearly 10:1.^{2, 3} Thyroid enlargement can be diffuse or nodular.⁴ The majority of solitary nodules of the thyroid are localized, non- neoplastic lesions or benign neoplasms.³Fine needle aspiration cytology (FNAC) has been regarded as the first-line investigation in the management of thyroid lesions, especially solitary nodules. It is recommended as a screening tool to decide whether a patient requires surgical intervention or can be managed conservatively. Fine needle aspiration cytology (FNAC) is simple, less expensive, readily available, reliable, time saving, easy to perform, effective and almost accurate diagnostic technique for investigation of thyroid swelling.^5-8 The main aim of thyroid FNAC is to distinguish benign from malignant lesions. Some authors recommend fine needle aspiration (FNA) as the initial test in the evaluation of any thyroid nodule.⁹ Reporting of thyroid FNAC specimens follow a standard format that is clinically relevant in order to direct management.¹⁰ The National Cancer Institute Thyroid Fine Needle Aspiration State of the Science Conference, held in Bethesda in 2007 introduced “The Bethesda system of reporting thyroid cytopathology” [TBSRTC] as a standard, uniform six-tiered reporting system for reporting thyroid fine needle aspiration, which was first published in 2009 and revised in 2017.¹¹ for reporting thyroid FNA’s six categories are used, CATEGORY-I for Non diagnostic lesions or unsatisfactory results, CATEGORY-II for benign lesions, CATEGORY-III for Atypia of undetermined significance (AUS) or follicular lesion of undetermined significance (FLUS), CATEGORY-IV for Follicular neoplasm or suspicious for a Follicular neoplasm, CATEGORY-V for suspicious for malignancy and CATEGORY-VI for malignant lesion. Each category has an implied cancer risk which ranges from 0-3% for “Benign” category and up to 100 % for “malignant category”. These cancer risks have been updated in 02017 revision. The present study was conducted to categorize thyroid swellings according to Bethesda System and their cancer risk stratification.

This was descriptive, cross-sectional study conducted in Cytology and Histopathology sections of Pathology department at a tertiary health care center in Jalna, Maharashtra, from January 2022 to June 2023. Sample size came out 162 which was calculated by formula, sample size =Z1-a/2 2p(1-p)/d2.

Inclusion criteria: All patients willing for FNAC of thyroid swelling and willing to give written informed consent were included in the study.

Exclusion criteria: Patients having midline neck swellings which do not move with deglutition, patients not willing to give written informed consent and critically ill patients were excluded from the study. The objectives of the study were 1. To assess the accuracy of thyroid lesion cytology, with application of TBSRTC, in correlation with final histopathological diagnosis and 2. To assess rate of malignancy (malignant risk) in each TBSRTC category.

METHODOLOGY:

After obtaining the approval from the Institutional Ethical Committee, the study was conducted in accordance with the protocol, Declaration of Helsinki, ICH, Good Clinical Practice (GCP) guidelines, and the ICMR guidelines for Biomedical Research on Human Subjects. All the eligible patients were explained in detail the study procedure to fullest extent possible in language best understood by them. Patients coming for thyroid gland FNAC’s during the period mentioned above were included after taking written informed consent. Relevant clinical details such as presenting complaints, age, sex, findings on local examination and details of thyroid function tests, ultrasonography (if available) were recorded in pre designed case record form. To perform FNAC, Patient were given a comfortable position with extension of neck and explained about the procedure. Patients were instructed not to talk or deglutinate during aspiration. After fixing the swelling with one hand and cleaning overlying skin with spirit swab, direct per cutaneous fine needle aspiration was performed with 23- or 25-gauge needle. One to more passes were given depending upon the size, nodularity and variation in consistency of the lesion. Air- dried and alcohol- fixed smears were prepared for each patient. Air - dried smears were stained with May-Grunwald Giemsa stain (MGG) and fixed smears were stained with Hematoxylin and Eosin stain (H&E). These slides were reported by cytopathologist and categorized according to TBSRTC criteria. These patients were followed up and if they were undergone for thyroidectomy, their biopsy specimens were processed for histopathology. Correlation between cytological and histopathological diagnosis was checked for these patients. For histopathological examination thyroidectomy specimens were received in 10% formalin. Gross features of the specimen were noted and grossing was done to give small pieces for further processing. The tissue went through steps of fixation, dehydration, clearing, rehydration and paraffin embedding in an automatic tissue processor. Then paraffin blocks were prepared and tissue sections were cut by Leica rotary microtome. These sections were stained with Hematoxylin and Eosin stain and reported by histopathologist.

DATA ANALYSIS PROCEDURE:

The data was entered in Microsoft excel and statistical analysis was performed. The frequency of various TBSRTC categories were determined in the form of percentage and Risk of malignancy [ROM] was calculated for each category of TBSRTC by dividing total number of confirmed malignant cases on histopathology to total number of cases undergoing histopathology in that category.

In this study total 210 cases of thyroid lesions FNAC were included. Age of the patients ranged from 5 to 70 years. Most of the patients have age between 30-39 years (29.52%), followed by 20-29 years (23.33%) (Table No 1). In the present study out of 210 cases, 188 (89.52%) were females and 22 (10.47%) were males (Table No 2) In present study, the spectrum of thyroid lesions on cytology was unsatisfactory, colloid nodule, colloid cyst, Hashimoto thyroiditis, nodular goitre, thyroglossal cyst, atypia of undetermined significance, follicular neoplasm, suspicious for malignancy, papillary carcinoma and medullary carcinoma. Most common cytological lesion in females was nodular goitre 109 out of 188 cases followed by Hashimoto thyroiditis 29 out of 188 cases. Most common cytological lesion in males was nodular goitre 12 in 22 cases followed by follicular neoplasia (4 in 22 cases).

Table No 1: Age wise distribution of study subjects.

Table No 2: Gender wise distribution of study subjects.

Table No 3: Gender wise distribution of thyroid lesions on cytology

Table No 4: Distribution of cytology diagnosis according to TBSRTC categorization.

Table No 5: Distribution according to Histopathological Diagnosis

Table No 6: Distribution of non-neoplastic and neoplastic lesions on HPE in various TBSRTC Categories

FNAC differentiates thyroid lesions in benign and malignant and helps in guiding therapeutic protocols. In non-neoplastic lesions it reduces unnecessary surgery and in malignant nodules, helps in timely clinical intervention. The present study was conducted to categorize FNA smears of thyroid enlargements according to Bethesda System and their cancer risk stratification.

In this study total 210 cases of thyroid lesions FNAC were included. Age of the patients ranged from 5 to 70 years. Most of the patients have age between 30-39 years (29.52%), followed by 20-29 years (23.33%) (Table No 1). The findings of present study were comparable with study done by Nandedkar S et al.² in which most of the patients (75.5%) were in age range of 21-50 years. In study done by Garg S et al.¹² maximum incidence of thyroid lesions was seen between 31-40 years (35%). In study done by Gupta A et al.¹³ mean age of patients was found to be 41.6 years and most common age range was 30-39 years. In the present study out of 210 cases, 188 (89.52%) were females and 22 (10.47%) were males (Table No 2). There was a preponderance of female gender which was comparable with studies of Kamboj M et al.¹⁴, Syed M et al.¹⁵, Bayak BY et al.¹⁶, Fischer GK et al.¹⁷ and Sharma A et al.¹⁸

Most of the thyroid lesions (86.19%) had size of 2-5 cm. which was comparable with the studies done by Bayrak BY et al.¹⁶ and Vargis RK et al.¹⁹ Maximum number of cases presented as solitary nodule 147/210 (70%) followed by diffuse swelling 51/210 (24.28%). Study done by Vargis RK et al.¹⁹ had maximum cases with diffuse swelling about 168/428 (39.25%) followed by solitary nodule presentation in 156/428 (36.44%).

The FNAC aspirates of thyroid lesions were categorized into six categories according to TBSRTC.

Category I (Non-diagnostic) included 3 out of 210 cases (1.42%). One patient had cyst fluid with cystic macrophages and two cases had hemorrhage with scanty cellularity on cytology. Studies done by Kamboj M et al.¹⁴, Bhartiya R et al.²⁰, Ren Y et al.²¹ had 18.6%, 5.88%, 4.7% cases respectively in category I.

Number of cases in Category II (Benign) were 178 out of 210 (84.76%) in which spectrum of lesions found were colloid nodule in 16 (7.61%), colloid cyst 9 (4.28%), Hashimoto thyroiditis 30 (30%), nodular goitre 121 (57.61%) and thyroglossal cyst 2 (0.95%). Similar studies were done by Choden S et al.²², Garg S et al.¹² and Bakiarathana A et al.²³ in which cases in category II were 82%, 78%, 75.9%, respectively.

Category III (AUS/FLUS) in present study only one case out of 210 cases (0.47%) had scant cellularity comprising of atypical cells in small clusters in background of hemorrhage. Occasional cells showed dense eosinophilic granular cytoplasm. No colloid was identified. Number of cases in other comparable studies done by Bakiarathana A et al.²³ and, Sonam Choden et al [93] were 1.2%, and 1.4%, respectively in category III.

Number of cases in Category IV (FN/SFN) were 23 out of 210 (10.95%) which had moderate to rich cellular harvest with sheets and clusters of follicular epithelial cells showing microfollicular pattern. Follicular cells were monomorphic having round to oval normochromic nuclei with moderate amount of cytoplasm in the background of scant colloid. Comparable to our study, findings of Nandedkar et al [2]11 in which 9.07% cases were in category IV.

Number of cases in Category V (SFM) were 3 out of 210 cases (1.42%) which had high cellularity with follicular epithelial cells arranged in sheets and clusters. These hyperplastic clusters showed cells with mild overlapping, overcrowding, enlarged nuclei with grooving, irregular nuclear outlines and scant amount of cytoplasm. Colloid was scanty to absent. Similar findings were obtained by Nandedkar S et al [2], Bhartiya R et al.²⁰, and Bakiarathana A et al.²³ having 1.15%, 2.52% and, 2.6% cases in category V, respectively.

Number of cases in Category VI (Malignant) were 2 out of 210 cases (0.95%). On cytology one case was diagnosed as papillary carcinoma and one as medullary carcinoma. Cytological findings in case of medullary carcinomas were rich cellular harvest along with dispersed cell population having plump ovoid to spindled cells. These cells had round to oval nucleus with coarse chromatin and moderate amount of cytoplasm. Binucleation and multinucleation was seen in cells. Some of the cells had intranuclear inclusions. Magenta Pink eosinophilic amorphous material was identified in Giemsa stain. The case of papillary carcinoma also had rich cellularity with follicular epithelial cells arranged in sheets and papillary patterns having cells with irregular outlines. These cells had enlarged nuclei with overlapping, crowding, at places grooving with powdery chromatin. Studies conducted by Ren Y et al.²¹, Nandedkar S et al [2] 11, and Garg S et al [86] 12 found 1%, 1.98%, and 4 % cases respectively in Category VI.

Out of 210 cytology cases, we received biopsy specimens of 50 cases (23.80%) for HPE which is comparable with most of the similar studies. We did not receive HPE specimens of cytology cases in TBSRTC category I. Out of 178 cases in category II, biopsy specimens of 34 cases were received and out of 23 cases in category IV, biopsy specimens of 11 cases were received. Out of 3 cases in category V, biopsy specimens of 2 cases were received. Biopsy specimens of all cases of category III and VI were received.

The spectrum of thyroid lesions on histopathology were Hashimoto thyroiditis (1 case), multinodular goitre (20 cases), multinodular goitre with hyperplastic nodule (4 cases), adenoma (14 cases), follicular carcinoma (3 cases), (papillary carcinoma (7 cases) and medullary carcinoma (1 case).

Out of 50, 39 cases were diagnosed as benign and 11 cases were diagnosed as malignant on histopathology. Among benign cases, multinodular goitre was most common followed by adenoma. Amongst malignant cases, papillary carcinoma was most common followed by follicular and medullary carcinoma.

Our study showed sensitivity of 62.5%, specificity 100%, PPV 100% and NPV 73.52% which was comparable to study done by Machala E et al.²⁴ In both these studies the false negative cases were more and false positive cases were less. In our study specificity, PPV, NPV were comparable with Singh P et al.²⁵ and other similar studies.

In present study risk of malignancy (ROM) could not be calculated in category I as no biopsy specimens were received. In category III only one case was included on cytology which was benign on HPE. In category II the ROM was higher than Bethesda system as more biopsy specimens were received in this category leading to detection of more false negative cases. The ROM for category IV was slightly more than the recommended risk by Bethesda system. ROM for category V and VI was comparable with other similar studies. ROM in study done by Bakiarathana A et al.²³ in category II, III, IV, V and VI were 8.5%, 66.7%, 63.6%, 100% and 100% respectively.

Risk of neoplasm (RON) helps in overall estimation of both benign and malignant lesions. In category II risk of neoplasm was 26.47% due to false negative reporting of nine cases of category II that were two cases of papillary microcarcinoma and seven cases of adenoma on cytology. RON was accurately predicted in category III, IV, V and VI in our study. RON in study done by Bakiarathana A et al.²³ in category II, III, IV, V and VI were 14.1%, 100%, 81.8%, 100% and 100% respectively.

FNAC is safe, cost effective, invaluable rapid tool helps in diagnosis of thyroid lesion with a higher degree of accuracy. The application of Bethesda system leads to more precise diagnosis of thyroid lesions and helps in standardization of thyroid cytology reporting with improved clinical outcome.

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