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Table of Content - Volume 20 Issue 2 - November 2021


 

Cytomorphological spectrum of thyroid lesions and its histopathological correlation in a tertiary care centre

 

Sakshi Taleja1, Syed Sarfaraz Ali2*, Kamarunisha Kalathingal3

 

1Senior Resident, 3Assitant Professor, Department of Pathology, LN Medical College and JK Hospital Bhopal, Madhya Pradesh, INDIA.

2Assistant Professor, Department of Pathology, LN Medical College and JK Hospital Bhopal, Madhya Pradesh, INDIA.

Email: sarfarazhayaz@gmail.com

 

Abstract              Background: Thyroid diseases are amongst the commonest endocrine disorders worldwide. FNAC of thyroid has been increasingly utilised for investigation of thyroid lesion such as solitary thyroid nodules, diffuse lesions, confirmation and categorisation of clinically obvious thyroid malignancy, evaluation of small lesions suspicious of malignancy. Histopathology gives a definitive diagnosis of whether it is benign or malignant. Aim And Objective: This study was conducted to evaluate the spectrum of various neoplastic and non-neoplastic conditions encountered in thyroid lesions and categorised according to Bethesda classification and to correlate cytological findings with histological findings wherever available, in our department over a period of three years. Material And Methods: A hospital based 3 years retrospective study of all thyroid lesions in the department of pathology. Result: Studied 100 cases, of which 70% cases were non neoplastic lesions and 30% were neoplastic. Out of 100 cases, histopathology of 35 cases were available. A cytohistologic concordance was achieved in 94.73% of the lesions. There were 3 false negative cases diagnosed on FNAC. The sensitivity and specificity of the method was 94.73% and 100% respectively. Conclusion: FNAC is simple, easy to perform and cost effective tool for the diagnosis of thyroid cancer. This can be used as safe outpatient procedure with minimal discomfort to the patient and has high sensitivity and specificity.

Keywords: Thyroid lesion, FNAC, Bethesda.

 

INTRODUCTION

Thyroid lesions are fairly common worldwide and are frequently encountered in clinical practice. Thyroid lesions may be developmental, inflammatory, hyperplastic and neoplastic.1 The incidence of palpable thyroid nodules in the general population is 4-5%. This incidence increases with age, a history of radiation exposure and with a diet which contains goitrogenic material. Thyroid nodules are more common in women.2 Fine Needle Aspiration Cytology (FNAC) is a simple, readily available, reliable, time saving, minimally invasive, cost effective method. It is a highly sensitive and specific technique applied routinely as a useful and indispensable method to diagnose thyroid lesions.3 Thyroid cytology can be used in two ways: therapeutic and diagnostic.4 Therapeutic function is when patient gets relieved from compressive symptoms after aspiration of fluid from their thyroid swelling.5 Detection of thyroid neoplasm for surgical resection and identification of non-neoplastic lesions that can be managed conservatively is a diagnostic function of cytology.6 Previously, thyroid cytology had multiple categories and terminologies. This confusion was resolved by The Bethesda System For Reporting Thyroid Cytopathology introduced in 2007. The Bethesda system unified the terminology and morphologic criteria along with the corresponding risk of malignancy.7 Even with recent advances, FNAC has it’s own limitations. Variation in the skill and sampling technique of the person performing FNAC, vascularity of thyroid swelling, scanty sample obtained during the procedure and experience of the pathologist are factors which present problems in the definitive diagnosis.8Histopathology gives a definitive diagnosis of whether it is benign or malignant. This study was conducted to evaluate the spectrum of various neoplastic and non- neoplastic conditions encountered in thyroid lesions and categorize them according to Bethesda classification. To correlate cytological findings with histological findings wherever available, in our department over three years.

 

MATERIAL AND METHODS

This is a retrospective study of thyroid lesions carried out at Department of Pathology, L.N. Medical college and J.K. Hospital, Bhopal. Records of 100 patients were studied retrospectively over the three years. All patients with thyroid swelling, irrespective of age who have undergone FNAC of the swelling followed by its subsequent Histopathological examination were included in the study. All FNACs were conducted by the pathologist, as outpatient procedure, under aseptic precautions, using 10cc syringes and 23gauge needle. Two to three passes were made. A minimum of six slides were smeared with the aspirate. Smears were stained with Papanicolaou stain and Giemsa stain. Out of the 100 cases, histopathology of 35 cases was available and assessed on routine H andE stains.

 

RESULTS

Our study deals with the FNAC of the palpable thyroid lesions and determination of the diagnostic accuracy of the aspiration cytology with histopathologic correlation. Duration of this study was 3 years. FNACs of 100 cases of thyroid were studied of which biopsy was available for 35 cases. Of the total patients 74 were female patients and 26 were male. Females comprised 74% and males comprised 26% of the total cases. Most of the patients belong to 3rd decade followed by fourth decade. (Fig1)The male to female ratio being 1:2.8 of thyroid lesions.

 

On gross examination of the FNAC, the majority aspirates were hemorrhagic followed by colloid like aspirate. Out of 100, 73 cases (73%) were non-neoplastic and 27 cases (27%) were neoplastic disease. Among the non-neoplastic swellings, colloid goitre was most common with 58 cases, followed by Hashimoto thyroiditis with 18 cases and 8 cases of multinodular goitre. Among the neoplastic thyroid swelling, follicular neoplasm was most common with 18 cases. According to the Bethesda system of reporting thyroid lesion, non-diagnostic category (Group1) included 7 cases (7%) and histopathology was not available in any of the case of this category. Out of 93 satisfactory samples, 66 cases were diagnosed as benign (Group2), 2 cases were diagnosed as Atypia of undetermined significance (AUS) (Group 3), 18 cases were diagnosed as follicular neoplasm (Group4), 2 cases were diagnosed as Suspicious for malignancy (Group 5) and 5 cases were malignant (Group 6).

Table 1: Distribution of neoplastic and non-neoplastic lesions based on cytological study

Lesions

Diagnosis

FNAC

n %(100%)

Non- Neoplastic

Colloid goitre

MNG

Nodular Goitre

Hashimoto’s Thyroiditis

50

8

8

18

 

 

73%

Neoplastic

Follicular Neoplasm

Papillary Ca

Medullary Ca

Anaplastic Ca

18

3

1

1

 

27%

Post-operative histopathological examination available in 35 cases out of which 27 cases were found non-neoplastic and 8 cases were found neoplastic. In our study, most common benign lesion on histopathology was goitre i.e. simple colloid goitre and multinodular goitre. Out of malignant lesions there were 5 cases of papillary carcinoma, 2 cases of follicular carcinoma and 1 case of medullary carcinoma. Out of 8 histologically proven malignant cases, 7 were malignant on cytology as well. There was 1 case which was benign on cytology but turned out to be malignant on histopathology-reported as goitre on cytology but diagnosed as papillary carcinoma on histopathology. Out of 27 histologically proven benign cases, 21 were benign on cytology also. One case was reported as goitre on cytology and were diagnosed as Hashimoto thyroiditis on histopathology. 6 cases of follicular neoplasm were diagnosed as follicular adenoma, hurthle adenoma, Adenomatoid goitre and follicular carcinoma on histology. Since diagnosis of carcinoma needs histopathological evidence of capsular/vascular invasion by the tumour; hence, this was taken as a positive correlation only(Table2). A cytohistologic concordance was achieved in 94.73% of the lesions. There were 3 false negative cases diagnosed on FNAC. The sensitivity and specificity of the method was found to be 94.73% and 100% respectively.

Figure 1: Age wise distribution of thyroid lesions


 

Table 2: Distribution of histopathological diagnosis(n-35)

Conventional system

TBSRTC

CYTO

DIAGNOSIS

SURGERY

DONE

HISTOPATH

DIAGNOSIS

n

Non- diagnostic

Cat I

7

0

 

 

Benign

Cat II

66

22

Colloid Goitre

Multinodular Goitre

Hashimoto Thyroiditis

Papillary carcinoma

14

4

3

1

AUS

Cat III

2

1

Nodular Colloid Goitre

1

Suspicious for follicular neoplasm

Cat IV

18

6

Follicular Adenoma

Hurthle Adenoma

Adenomatoid Goitre

Follicular Ca

 

1

1

2

2

Suspicious for malignancy

Cat V

2

2

Colloid Goitre

Papillary Ca

1

1

Malignant

Cat VI

5

4

Papillary Ca

Medullary Ca

3

1

 

Figure 2                                                            Figure 3                                                            Figure 4

Figure 2: Colloid Goitre showing flat sheets of thyroid follicular cells with background showing thin colloid.(Pap,40x); Figure 3: Papillary carcinoma showing monolayered sheets of cells, synctial fragments with three dimensional papillary architecture( Geimsa:10x); Figure 4: Papillary carcinoma showing complex branching, papillae with fibrovascular core (HandE,10X)

 

Figure 5                                             Figure 6

Figure 5: Follicular neoplasm showing repetitive patterns of microfollicles (Pap,10x); Figure 6: Follicular neoplasm showing sheets and solid pattern of microfollicles (HandE,10x)

 


DISCUSSION

In the diagnosis of thyroid gland lesions, FNAC has gained the popularity as diagnostic tool due to its low cost and safe procedure with minimal risk to the patient and aid the clinician’s in the management planning. A total of 100 cases of thyroid swelling aspirations followed by histopathological diagnosis were included our study. The results of cytological findings and histopathological findings were compared and scrutinized for accuracy and other statistical values. In our study, the common age group with thyroid nodules was in the third and fourth decade. Mean age of present study i.e. 39.8. The female preponderance observed in the study similar to that reported in by Manoj Gupta et al.9 Bethesda system of reporting thyroid cytopathology was applied on our 100 thyroid aspirates. 7cases (7%) we found to be Non-diagnostic or unsatisfactory were which correlates with study of Yassa et al.10 who reported 7% unsatisfactory smears in their study. In the present study, 73 cases were non- neoplastic and 27 cases were neoplastic lesions with a non-neoplastic to neoplastic ratio of 1:2.7.  There were 66 cases (66%) which were categorised as benign in our study which was comparable with Nayar and Ivanovic11 who reported (64%) benign cases in their study. Considering all lesions, Colloid goiter is most frequently involved, followed by multinodular goitre and Hashimoto thyroiditis. Most of the non-neoplastic lesions were treated conservatively. There were less number of cases (2%) diagnosed under category AUS in the present study which could be explained by the strict adherence to diagnostic criteria and the cytopathologist effort in our practice setting to avoid ambiguity and keep the use of AUS to a minimum. Mondal et al.12have also reported lower percentage of AUS (1%) in their study. There were 18 cases (18%) diagnosed as follicular neoplasm which comes under category IV of TBSRTC. It has an advantage of minimal bias of separation of Follicular Adenoma and low grade Follicular Carcinoma. This could be correlated with the study done by Agrawal et al. 13which had reported it as (8.63%) cases in their study. Thyroid lesions categorised as “Suspicious for malignancy (SM)” in the present study were 2 cases (2%) of the total cases. This finding is in concordance with the study of Nandedkar et al. 14who have reported 1.9% thyroid lesions as SM.  Histological correlation was available in only 35 cases in our study. 22 cases correlated with cytological diagnosis whereas 3 showed discordance. Three cases reported as non-neoplastic lesions on FNAC turned out to be follicular carcinoma, lymphocytic thyroiditis and papillary thyroid carcinoma.

 

CONCLUSION

FNAC is a safe and reliable technique in the primary diagnosis of thyroid gland lesion. A six tier reporting system for thyroid FNA is categorising the lesions and determining which patients need surgery versus follow up and also guide the clinician on the extent of surgery. FNAC has a high diagnostic accuracy, though rate of characterization of specific type of tumour is lower, due to variable cytomorphology. In such cases, histopathology examination may prove to be accurate for diagnosis.

 

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