Introduction
Thyroid disorders are very common cause of endocrinological disturbances.1 In our country many people are at risk for developing iodine deficiency disorders because goitrogens like cauliflower, cabbage, mustard seeds, radish and turnip are an integral part of diet so it is imperative to evaluate a diagnostic method whereby such disorders can be easily diagnosed.2
Fine needle aspiration (FNA) is an established test for the evaluation of thyroid nodule.3 FNA of thyroid is a rapid, minimally invasive and first line procedure in the evaluation of thyroid nodules.4, 5, 6
However, despite its widespread use FNA suffered from a reporting confusion due to multiplicity of category names, descriptive reports without categories and variable surgical pathology terminology.7 The framework for The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) was formed by thyroid FNA of the science conference 2007.8, 9
TBSRTC provides a 6-tiered diagnostic framework that uses defined criteria to promote uniformity in the reporting of thyroid aspirates. One of the major advantages of this scheme is that the individual diagnostic categories are associated with defined risks of malignancy, allowing for standardized management algorithms for each diagnosis.10
Aim and Objectives
This study was undertaken to evaluate the usefulness of The Bethesda System for Reporting thyroid Cytopathology in Thyroid FNA.
Materials and Methods
Prospective study was conducted in Department of Pathology at tertiary health care center, Solapur for the period of 2 years which included 165 patients presenting with palpable thyroid swelling from Department of Surgery and E.N.T.
Under all aseptic precautions FNAC was done and smeared slides fixed and stained with H & E. Reporting of FNA was done by using TBSRTC. Surgical thyroid specimens received were processed routinely and prepared slides were stained with H & E. The permission from ethical committee has been taken.
Observations and Results
Out of 165 cases, 146 benign cases of category II were advised clinical follow up out which 51 cases were subjected to surgical lobectomy. All the three cases from category III were available for histopathological follow up. Out of 7 cases of category IV, 4 cases underwent surgical lobectomy. Two cases of category V were not available for follow up. All 3 cases of category VI were subjected to surgical management and available for histopathological follow up. (Table 1)
Table 1
Distribution of lesions in the Bethesda categories as per our study (n=160)
Table 2
Age wise incidence of various categories according to Bethesda system (n=165)
Maximum lesions were found in female than males in the proportion of 10:1. Figure 1 indicates the sex wise incidence of thyroid lesions.
In the present study, colloid nodule comprised of 127cases (87%) which was the predominant group in the benign category, followed by 18 cases (12.3%) of Hashimoto’s thyroiditis and least being Granulomatous thyroiditis with 1 case (0.7%). (Figure 2)
Figure 1
Photomicrograph of category II hashimoto’s thyroiditis showing hürthle cell change in many follicular cells on background of lymphocytes. (H&E X 100)
Figure 2
Photomicrograph of category III - follicular lesion of undetermined significance showing sparsely cellular aspirate with predominance of micro-follicles and scant colloid. (H&E X 100)
Figure 3
Photomicrograph of category IV – suspicious for follicular neoplasm showing cellular aspirate with micro- and macro-follicles.(H&E X 100)
Figure 4
Photomicrograph of Category IV suspicious for follicular neoplasm- Hurthle cell type (H&E X 100)
Discussion
During the period of 2 years, a total number of 1768 FNACs were done, out of which 165 were belonging to thyroid gland. So the thyroid lesions in our study constituted 9.33% of all FNACs done during the study period.
In the present study, cytodiagnostic evaluation of thyroid lesions were done and classified according to The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC).
Table 3
Comparison of FNAC diagnosis based on Bethesda classification
Age distribution of the present study was comparable to Handa et al.11 and Parikh U. R. et al.12 The mean age in the present study was 39.72 years which was comparable with Handa et al,11 Gupta et al,13 Rangaswamy et al,14 Parikh U. R. et al.,12 Vinay Kumar R et al15 and Ritica Chaudhary et al.16
Female to male ratio in the present study was 10:1 and was comparable with studies of Renuka I V et al,17 Sunita Bamanikar et al18 and Silvermann JF et al19 which had female to male ratio 9:1, 8.6:1 and 10.8:1 respectively.
For a thyroid FNA specimen to be satisfactory for evaluation, at least 6 groups of benign follicular cells are required, each group composed of at least 10 cells. There are several exceptions like any specimen that contains abundant colloid is considered adequate, even if 6 groups of follicular cells are not identified.
The benign category had 146 cases (88.5%) and in this cases unnecessary surgery can be avoided.
Some thyroid FNAs could not be clearly categorized benign or malignant and reported as atypia of undetermined significance (AUS). TBSRTC suggests that this category should not be used indigenously.
Follicular neoplasm (IV category) was subjected for hemithyroidectomy and risk for malignancy is bout 15-30% of all cases.
Both cases of Suspicious of malignancy (category V) were given as suspicious of papillary carcinoma because of very few follicular cells showing presence of internuclear cytoplasmic inclusion. (Figure 7)
In category VI, out of 3 cases, on histopathology 2 were reported as papillary carcinoma of thyroid in which follicular cells were arranged in papillary pattern with cell having nuclear features like grooves and inclusions. Remaining one case was categorized as medullary carcinoma of thyroid as it showed moderate cellularity polygonal to round cells having round nuclei and coarse chromatin. (Figure 8)
Conclusions
The primary objective of FNAC of the thyroid is to differentiate those patients who require surgery for a neoplastic disorder from those who have a functional or inflammatory abnormality and who can be followed clinically or treated medically.
The introduction of TSBRTC has brought about standardisation in the reporting of thyroid FNAC.
The TSBRTC helps to classify thyroid lesions under specific categories thus providing an implied risk for malignancy and guidance towards surgical management which also allows easy and reliable sharing of data between different laboratories. The clinicians are also benefitted because of the management plan it suggests. TBSRTC bridges the gap between clinician & cytopathologist. TBSRTC is a universal terminology & its use should be encouraged.
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