The Spectrum of Thyroid Lesions on Cytology in a Secondary Care Centre, Karkala, Karnataka

Thyroid swelling is the most common presentation seen in routine practice. Approximately 67% of people with thyroid nodules are non-palpable and asymptomatic [1]. The main objective of Fine-Needle Aspiration Cytology (FNAC) of the thyroid is to categorise those patients who need surgery from those who have a functional or inflammatory lesion and can be followed up or treated medically. Children and adolescents should be included as they may also harbour malignant tumors [2]. 

 The cytologic criteria to classify thyroid lesions varies between pathologists and between institutions [3]. “The Bethesda System for Reporting Thyroid Cytopathology” (TBSRTC) was introduced to improve communication between pathologists and clinicians [4]. TBSRTC was introduced in 2007 to standardize terminology and to categorize morphological criteria in Fine Needle Aspirations (FNAs) of thyroid lesions [5]. 

However, the success of FNA is dependent on several important contributing influences including pathologist experience, technician skill in smear preparation, cytological interpretation and a rational analysis, correlating cytological and clinical information of an individual patient [6].

The study was done in Dr.T.M.A Pai Rotary hospital, Karkala, Udupi between April 2023 to March 2024. A retrospective analysis of 25 cases with thyroid swelling was done. 

Inclusion Criteria 

All patients presenting with thyroid swelling referred by the clinician were included in this study. Clinical details like age, sex and relevant investigations like USG, thyroid profile was considered. FNA of thyroid swelling was done using 24-gauge disposable needles under all aseptic precautions. Minimum four slides were prepared for each case. The slides were immediately fixed in 95% ethyl alcohol for a period of 40 minutes. The slides were stained with haematoxylin and eosin and Papanicolaou stain (PAP). In cases where cellularity was scanty, FNAC was repeated. 

All the thyroid lesions were categorised according to TBSRTC as follows: Category I-Non-diagnostic or Unsatisfactory, Category II-Benign, Category III-Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance (AUS/FLUS), Category IV-Follicular neoplasm/Suspicious for Follicular Neoplasm (SFN), Category V-Suspicious for Malignancy (SFM) and Category VI-Malignant. 

Statistical Analysis 

The results were analysed using descriptive statistics.

The study included 25 cases with the minimum presenting age 20 years to maximum presenting age 73 years. Majority of the case are falling between the age group of 30-40 years and 50-60 years of age as shown in the bar graph 1.

 Bar Graph 1: Showing frequency of age distribution among cases with thyroid leasions. 

As per table 1 and bar graph 2, most cases in the study population presented with Bethesda Category II lesion (60%) which was found to be statistically significant (p < 0.05), (Benign follicular nodule +/- lymphocytic thyroiditis, colloid nodule, adenomatoid nodule). 

Table 1: Showing distribution of TBSRTC category.

 Bar Graph 2: showing percentage distribution of TBSRTC category. 

As per table 2 and bar graph 3, spectrum of thyroid lesions is seen that the most common spectrum was seen, which was benign follicular nodule +/- lymphocytic thyroiditis in 32% of cases categorized to Bethesda Class II. This was found to be statistically significant (p < 0.05), followed by colloid nodule +/- lymphocytic thyroiditis in 24% of cases also in Category II. 

Table 2: Showing distribution of different diagnosis.

 Bar Graph 3: Showing distribution of different diagnosis. 

As per bar graph 4, the study was female preponderance with the age groups 30-40 years and 50-60 years were found to be statistically significant (p < 0.05) that was estimated to be 84% of the total number of cases and the male population contributed to 16% of the cases.

 Bar Graph 4: Showing percentage distribution of sex among patients with thyroid lesions. 

FNAC is practised worldwide, as the initial test for thyroid lesions to categorise patients in planning treatment modalities [7]. FNAC has become essential in selecting cases that need surgery and in providing a pre-operative morphological diagnosis in obviating unnecessary surgeries as well as in planning proper surgical and other treatment protocols [8]. 

 Different classification system had been used for thyroid FNAC before introduction of Bethesda system of thyroid cytology. TBSRTC complements cytological findings from thyroid FNA and represents a unity among clinicians and pathologists in different areas of medicine [9]. This study was done with the aim to categorize various thyroid lesions and to evaluate the efficacy of the newly proposed six-tier classification system in reporting thyroid FNA results. 

 The sensitivity and diagnostic accuracy of thyroid surgery have been shown to be as high as 85-95% in experienced hands [10,11]. Positive predictive value of 89-98%, negative predictive value of 94-99%, [12,13], and false negative rates as low as 5-10% [14], have established FNA as an invaluable diagnostic modality. There are literatures claiming the accuracy and usefulness of thyroid cytology and there is also evidence showing possible limitations and pitfalls of this procedure [15]. 

 In this study, 64% of thyroid lesions were in Category II, 8% were in Category IV, 8% were in Category III and 20% were in Category I. The number of benign cases were high in our study. The higher rate of benign cases are also seen in other studies [16-18]. Upadhyaya et al, found that TBSRTC helps in reduction in percentage of indeterminate cases and uniformity in reporting among pathologists [19]. The thyroid lesions which were of TIRADS IV and TIRADS V category were referred to tertiary care centre which could be the reason for TBSRTC category IV and V lesions not being reported in our study. 

Study of Mehra P and Verma AK showed the following distribution of various categories from 225 evaluated thyroid nodules: 7.2% ND/UNS, 80.0% benign, 4.9% AUS/FLUS, 2.2% FN, 3.5% SFM, and 2.2% malignant [20]. 

Yang et al, found 10.4% cases as unsatisfactory, 64.6% were benign, 3.2% were AUS, 11.6% were follicular neoplasm, 2.6% were suspicious for malignancy and 7.6% were classified as malignant [16]. 

Theoharis et al, found 11.1% unsatisfactory, 73.8% benign, 3% indeterminate, 5.5% follicular neoplasm, 1.3% suspicious for malignancy and 5.2% malignant [17]. 

Similar study was done by Sarkis et al. [19]. They found 12.8% were non-diagnostic, 74.7% benign, 4.7% atypia of uncertain significance, 4.7% suspicious for follicular neoplasm, 0.8% suspicious for malignancy and 2.3% malignant. 

 However, this study was found to be effective in categorizing the thyroid lesions based on The Bethesda system of Reporting Thyroid Lesions and avoiding unnecessary surgical intervention for benign cases who could be managed by non-surgical modalities [21-23].

The sample size in this study was small compared to other studies carried out in tertiary centres within the same given time. Therefore, accuracy of the result could be significant on increasing the sample size. Due unavailability of Anti TPO test a complete workup of thyroiditis was not done.

FNAC is the first line screening test that is cost effective and rapid test to assess different thyroid lesions. Also, TBSRTC is very useful as a standardized system of reporting thyroid cytopathology, that has brought uniformity in reporting, improving communication between cytopathologists and clinicians resulting in best management approaches, avoiding unnecessary surgeries and their complications. However, there are a few draw backs in in missing the diagnosis on FNAC could be mainly due to sampling error, or co-existing benign and malignant lesion leading to erroneous interpretation. These pitfalls can be corrected by ultrasound guided FNAC especially for impalpable small thyroid lesions. However, clinical findings along with thyroid profile and thyroid scan should be assessed for comprehensive approach, definitive diagnosis and proper management of the patients.

No funding sources.

None declared.

Data collection and data interpretation was done by Dr. Rashmi R Shetty, manuscript writing by Dr. Sachin S. Shetty and Dr. Prashanthi Sushma Nagireddy and proof reading by Dr. Shantha Kumari and Dr. Namrata Rao.

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