Ultrasonographic and fine needle aspiration cytology correlation of thyroid gland lesions: a study of 100 cases

INTRODUCTION

Thyroid gland is unique among endocrine organs as it is the largest endocrine gland in the body and the first to develop in the fetal life amenable to direct physical examination because of its superficial location it allows excellent visualization and evaluation of normal anatomy and pathologic condition by high resolution real-time grey scale sonography. There is approximately 4-5% incidence of clinically apparent thyroid lesions in general population.¹ Thyroid nodules are about four times more common in females than in males. The majority (90%) of thyroid lesions are benign as malignancy occurs only 1 in 10 thyroid nodules.² The overall incidence of malignancy in solitary thyroid nodule ranges between 10% and 30%.^1,3 The goal of USG and FNAC diagnosis work up now is to select those patients for surgery who have a high likelihood of harboring malignancy in the nodule.⁴ USG and FNAC are commonly used but there are drawbacks of each technique and the final answer to the problem is still elusive.⁵

Ultrasonography is the single most valuable imaging modality in the evaluation of the thyroid gland.

Indications for thyroid USG include evaluation for palpable thyroid lesion or suspected thyroid enlargement and workup of thyroid lesions discovered incidentally.⁶ In patients with thyroid swellings, gray scale and color Doppler USG are used to evaluate its sonographic features, including size, shape, echogenicity (hypoechoic or hyperechoic), and composition (cystic, solid, hard or soft) and to determine the presence of coarse or fine calcification, a halo and margins, and internal blood flow.⁷ USG report as suggestive of malignancy if the nodule was solid or of mixed solid –cystic variety and a hypoechoic and non-haloed lesion.

FNAC provides the most direct and specific information and specific information about thyroid lesions. The use of FNAC reduces the number of thyroidectomies by approximately 50%, roughly doubles the surgical yield of carcinoma and reduces the overall cost of medical care in these patients by 25%.^8,9

The present study is undertaken to evaluate the utility of FNAC in preoperative diagnosis of various thyroid lesions and to evaluate the efficacy of in USG and FNAC differentiating between benign and malignant lesions.

Aims and objectives

• • To correlate the high resolution ultrasonography findings with the fine needle aspiration cytology report.
• • To confirm the USG and FNAC both the modalities are required before preparing the patient for thyroid surgery.
• • To determine sensitivity of high resolution ultrasonography and fine needle aspiration cytology using the histopathology report as reference standard.

METHODS

Type of study

Study was a retrospective study.

Selection criteria

Inclusion criteria

Inclusion criteria were all adult male and female patients with clinically palpable thyroid swellings in lower midline neck or on either side; signs and symptoms suggestive of thyroid disorder (hypo/hyperthyroidism).

Exclusion criteria

Exclusion criteria were all patients who have not given consent for fine needle aspiration cytology; all patients with bleeding diathesis; patient already diagnosed and treated for thyroid lesion; FNAC showing inadequate aspirated material.

Method of collection of data

100 patients, in the age group of equal to or above 18 years, with thyroid swellings referred to the department of ENT, Smt. Shardaben General Hospital, Smt. NHL Medical College, Ahmedabad during the period from July-2014, to July-2016 sent for USG and FNAC at radiology and pathology department respectively.

A structured pre-prepared case proforma was used to enter the patient details, clinical history, physical examination and investigations including thyroid function tests of patients who have met the inclusion and exclusion criteria. The ultrasound examination of the thyroid gland was performed in gray scale and color Doppler modes using a high resolution, 7.5–12 MHz, linear array transducer of TOSHIBA TA 311 Ultrasound machine. This was followed by fine needle aspiration cytology of the thyroid swelling after taking informed consent and after performing a coagulation profile. The high resolution ultrasound findings were correlated with the fine needle aspiration cytology report. In cases where surgery was done, USG and FNAC results were followed up with histopathology report.

Equipment

The ultrasound examination of the thyroid gland was performed using real time 2D gray scale and color Doppler modes using a high resolution, 7.5–12 MHz, linear array transducer of TOSHIBA TA 311 Ultrasound machine.

Examination technique

Both lobes of the thyroid gland including the isthmus were evaluated by TOSHIBA TA 311 machine unit using a 7.5 to 12 MHz linear transducer. With the patient supine and neck hyperextended, the entire gland was examined. Hyperextension of the neck was obtained by placing a pad under the shoulders. The superficial location of the thyroid permits sonographic demonstration of any subtle anatomical changes.

The neck was scanned in sagittal, transverse, and oblique sections to optimally visualize both lobes of thyroid, isthmus, carotid arteries, as well as internal jugular veins. Imaging of the lower poles of thyroid was improved by making the patient swallow. This tended to raise the thyroid gland in the neck.

The region of the carotid arteries and jugular veins laterally and supraclavicular fossa were also examined for any lymphadenopathy.

Scanning technique

Neck palpation: Before beginning the ultrasound scan, patient’s neck was palpated to find the size and location of nodule and tenderness if any. The patient was asked to swallow as the thyroid was palpated.

Scan image size: The image of the thyroid gland was enlarged to fill the entire viewing monitor which included carotids and jugulars in the field.

Transverse scan direction: Beginning transversely in the midpoint of the neck until thyroid tissue was identified. If the size of the thyroid mass was large and if it was not possible to image right and left lobes simultaneously, then two lobes were examined separately and later the texture compared bilaterally.

Longitudinal scan direction: After imaging the carotid artery longitudinally, the probe was slided medially to view the thyroid gland. If needed the transducer was angulated 10–20 degrees medially. This technique was very useful to determine if the mass was within the thyroid gland or extra thyroidal. Most extra thyroidal masses displaced the carotid artery and internal jugular vein medially.

FNAC technique

Before the ultrasound guided FNAC, the neck was hyperextended and the skin was cleansed with povidone – iodine (Betadine) solution. The needle was inserted through the skin of thyroid region in front of the neck at an oblique.

The needle used for thyroid FNAC was standard 1½” 25 gauge, non cutting bevelled edge needle. The needle was attached to a 10ml syringe. After introducing the needle, the needle was moved gently but rapidly through the nodule center under US guidance. Then gentle suction was done by putting the piston of the syringe. If the specimen contained much blood, a non-aspiration technique was used. In this, 25 gauge needle was inserted under ultrasound guidance into the thyroid gland and no suction was applied and this needle was moved in back and forth excursions. Due to capillary action the fluid of cells from the nodule moved into the needle. Such fluid specimen was often less bloody.

Two drops of the aspirate/fluid in the syringe were ejected over a clean slide and with the help of the other blank slide with 60° angle; the aspirate on the first slide was spread on it to form a film of coating on it. The slide making procedure was repeated once more and after smearing the second slide, these slides were put in a jar containing absolute alcohol for fixation. These two slides in alcohol along with container were sent to Pathology department for cytopathological study.

Statistical tool used to analyse data

In our study, out of 100 patients we had histopathological data of 53 patients.

Considering histopatho data as standard, comparing the results of USG and FNAC with the same, we found that Sensitivity of USG was 90.56% whereas that of FNAC was 96.47%.

On performing chi-square test for comparing the findings of USG and FNAC, it was found that two tailed chi-square value was 19.953^a which proved that results were significantly different from one other (p<0.001).

Based on the sensitivity and chi-square value obtained in our study, we can say that USG findings (sensitivity = 90.56%) were more significant as compared to FNAC findings (sensitivity=96.47%) for diagnosis of thyroid swellings.

RESULTS

Out of 100 patients studied, there were 10 males (10%) and 90 females (90%) with male to female ratio is 1:9. So, according to this study, thyroid lesions are commoner in females. The possible reason for this is due to the presence of estrogen receptors in thyroid gland in females.

In our study, the youngest patient was 17 years old and the eldest patient was 66 years. The average age of patients with thyroid lesions according to our study was 36.27 years. So, the thyroid lesions are commoner in females in their active reproductive age group and are uncommon in post menopausal age group.

In this study, 46 (46%) of the 100 cases presented with their clinical complaints dating under 6 months. There were 19 cases presenting with complaints lasting since 2 years of which 2 cases were malignancies (papillary carcinoma). So, most of the patients presented within 6months either due to cold/heat intolerance or easy fatiguability or even cosmetic disfigurment in few cases.

The majority 58 (58%) of the cases in this study were firm in consistency while 34 cases are soft in consistency of which most of the cases are of colloid goitre. 2 cases are of cystic consistency of which 2 casese are of colloid with cystic changes. Rest of them are hard in consistency of which 2 cases are of malignancy and 4 cases are of suspicious malignancy.

In 46 (46%) cases thyroid lesion is on the right side and 32 (32%) cases thyroid lesion is on the left side. 22 (22%) case involves both the lobes of gland. So in our study most common right side of lobe is involved.

In our study out of 100 cases 36 (36%) cases found to be colloid goitre, hypoechogenicity in 35 (35%) cases and isoechoigenicity in 1 cases. 26 (26%) cases were nodular goitre, 7 (7%) cases were hypoechoic and 19 (19%) cases were isoechoic. 20 (20%) cases were adenomas of wich 12 cases showed hypoechogenicity and 8 (8%) cases were hyperechoic. These 8 cases of adenoma with hyperechoigenicity were confirmed benign. 2 cases of hypoechoic nodule found malignancy and 4 cases of hypoechoic adenoma found suspicious malignancy. Out of 12 cases of thyroidis 2 were hypoechoic and 10 were heterogenous. So it suggests that hypoechoigenicity seen in malignant lesions.

Out of these 100 cases 20 (20%) cases were of adenoma, 36 (36%) were colloid goitre, 26 (26%) were nodular goitre, 12 (12%) were thyroiditis, 2 (2%) were malignancy, 4 (4%) case were suspicious malignancy. So in my study most common thyroid lesions are of adenomatous (Table 3).

In present study there were 11 cases were of adenoma, 24 cases were of multinodular goitre, 12 cases were of thyroiditis, 36 cases were of colloid goitre, 2 cases were of papillary carcinoma, 15 cases were of follicular neoplasm (Table 4).

In our study out of 100 cases 94 were benign according to USG out of which 12 were inflammatory (thyroiditis) and 82 were non inflammatory bening lesion of thyroid gland which includes adenomatous nodule, multinodular goitre, colloid goitre. Out of 100 cases 98 cases were benign according to fine needle aspiration cytology which includes 12 cases of thyroiditis and 86 were noniflammatory which includes adenoma, multinodular goitre, colloid goitre and follicular neoplasm. 4 cases were found suspicious malignancy in USG which were not confirmed by FNAC and 2 cases were of malignant lesion according to USG features they were confirmed malignant lesion (papillary carcinoma) of thyroid gland (Table 5).

In our study, out of 100 patients we had histopathological data of 53 patients.

Considering histopatho data as standard, comparing the results of USG and FNAC with the same, we found that Sensitivity of USG was 90.56% whereas that of FNAC was 96.47% (Table 6).

On performing chi-square test for comparing the findings of USG and FNAC, it was found that two tailed chi-square value was 19.953^a which proved that results were significantly different from one other (p<0.001) (Table 8).

Based on the sensitivity and chi-square value obtained in our study, we can say that USG findings (sensitivity=90.56%) were more significant as compared to FNAC findings (sensitivity=96.47%) for diagnosis of thyroid swellings.

DISCUSSION

A total of 100 patients with various thyroid swellings were studied by high resolution ultrasound and with the fine needle aspiration cytology report. For the various thyroid swellings diagnosis according to ultrasound sonography and fine needle aspiration cytology is correlated in our study.

Sex distribution

Out of 100 patients studied, there were 10 males (10%) and 90 females (90%) with male to female ratio of 1: 9. Silverman et al study (1:10.8) also yielded similar findings.¹⁴ So, according to this study, thyroid lesions are commoner in females. The possible reason for this is due to the presence of estrogen receptors in thyroid gland in females. For the same reason, the level of thyroid hormones also changes according to the phase of menstruation.

Age distribution

In our study, the youngest patient was 17 years old and the eldest patient was 66 years. The average age of patients in Ankush et al study is 39 which is nearer to our study 36.27.¹⁵ The age distribution according to our study was similar to that of the previous studies. So, the thyroid lesions are commoner in females in their active reproductive age group and are uncommon in postmenopausal age group.

Duration of swelling

In this study, 46 (46%) of the 100 cases presented with their clinical complaints dating under 6 months. There were 19 cases presenting with complaints lasting since 2 years of which 2 cases were malignancies (papillary carcinoma). So, most of the patients presented within 6 months.

In study of Jain et al also found that majority (67.2%) of patients came with complaint of swelling of duration less than 6 months.¹¹ So, our study also confirmed the findings given by the other studies with respect to duration of swelling. Most of these patients presented within 6months due to either due to cold/heat intolerance or easy fatigability or even cosmetic disfigurement in few cases.

Consistency of swelling clinically

The majority 58 (58%) of the cases in this study were firm in consistency while 34 cases are soft in consistency of which most of the cases are of colloid goitre. 2 cases are of cystic consistency of which 2 cases are of colloid with cystic changes. Rest of them are hard in consistency of which 2 cases are of malignancy and 4 cases are of suspicious malignancy.

This observation is in line with the observations of Vyas et al who also observed that the consistency of most of swellings (58%) were soft while hard swellings were see in all cases of carcinomas.¹⁰ Hard consistency is seen in malignancy, probable reason is either because of loss of elasticity in the malignant tissues or because of the microcalcifications.

Echotexture of thyroid lobe and nodule

In our study out of 100 cases 36 (36%) cases found to be colloid goitre, hypoechogenicity in 35 (35%) cases and isoechoigenicity in 1 cases. 26 (26%) cases were nodular goitre, 7 (7%) cases were hypoechoic and 19 (19%) cases were isoechoic. 20 (20%) cases were adenomas of wich 12 cases showed hypoechogenicity and 8 (8%) cases were hyperechoic. These 8 cases of adenoma with hyperechoigenicity were confirmed benign. 2 cases of hypoechoic nodule found malignancy and 4 cases of hypoechoic adenoma found suspicious malignancy. Out of 12 cases of thyroidis 2 were hypoechoic and 10 were heterogenous. So it suggests that hypoechoigenicity seen in malignant lesions.

In study of Krishna et al, out of 80 cases 45 (56.25%) cases were colloid goitre.¹⁶ Almost 35 of these lesions were hyperechoic, 3 of the cases were isoechoic, and associated cystic changes cystic changes were there in 7 cases. 15 cases of follicular neoplasm were found to be hyperechoic. 8 cases of thyroid cyst found cystic changes. 10 cases of thyroidis were hypoechoic. 5 cases of malignancy showing predominantly hypoechogenic lesion.

Correlation between USG and FNAC

In present study, out of 100 (100%) patients we found 94 (94%) of Benign thyroid swelling by USG while 6 (6%) found malignant lesion. In addition diagnosis by FNAC, out of 6 (6%) malignant lesion 4 (4%) patients diagnosed as benign rest 2 (2%) patients are confirmed to be malignant.

Similar study done by Ankush et al have found out of 100 (100%) patients, (66%) of benign thyroid swelling by USG while (34%) found malignant lesion.¹⁵ In addition diagnosis by FNAC, out of (66%) benign lesion (64%) patients diagnosed as benign rest (2%) patients are confirmed to be malignant, same as out of (34%) malignant lesion (24%) patients diagnosed as benign rest (10%) patients are confirmed to be malignant.

In our study, out of 100 patients we had histopathological data of 53 patients. Considering histopatho data as standard, comparing the results of USG and FNAC with the same, we found that Sensitivity of USG was 90.56% whereas that of FNAC was 96.47%.

In study of Lokhande et al sensitivity of USG was 71.43% and of FNAC is 75%. So, these results are similar to present study.¹⁷

CONCLUSION

High resolution duplex ultrasonography is a safe, non-invasive, less time consuming, easy to perform, repeatable modality that causes minimal discomfort to the patient. Most importantly, it does not employ any ionising radiation which is harmful to the patient. Ultrasound is the gold standard for assessing the morphological structure of the gland along with the gland size. Color Doppler evaluation is a useful adjunct to gray scale ultrasound in the evaluation of thyroid swellings. Intralesional vascularity with an RI <0.4 is helpful in diagnosing malignant lesions while perilesional vascular pattern is helpful in diagnosing benign lesions. USG followed by FNAC increases the accuracy to diagnose various thyroid lesions so by which unnecessary thyroid gland surgery can be avoided. Ultimately High Resolution USG is better non invasive tool for diagnosis of various thyroid swellings and can also differentiate between benign and malignant lesion. FNAC also as confirmatory as USG. So both diagnostic modalities are required before planning the patient for thyroid surgery.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: The study was approved by the Institutional Ethics Committee

REFERENCES

1. 1. Altavilla G, pascale M, Nenci 1.FNAC of thyroid gland disease. Acta cytological. 1990;34:251-6.
2. 2. Matesa N. FNAC of the thyroid. Acta Clincroat. 2002;41:23-131.
3. 3. Bouvet M, Fiedldman JI, Gill GN, Dillmann WH Nahum AM, Russak V, et al. surgical management of the thyroid nodule: patient selection based on the results of FNAC. Laryngoscope. 1992;102:1353-6.
4. 4. Kapur. Solitary thyroid nodule. Indian J Surg. 1999;44:174-9.
5. 5. Watters AK, Ahiya AT. Role of USG in the management of thyroid nodules. AM J Surg. 1992;162:654-7.
6. 6. Sheth S. Role of Ultrasonography in thyroid Disease. Otolaryngol Clin N Am. 2010;43:239-55.
7. 7. Schlumberger MJ, Filetti S, Hay ID. Nontoxic Diffuse and Nodular Goiter and Thyroid Neoplasia. Willium Textbook of Thyroid Surgery. 12th ed. Volume 14. 2012: 443.
8. 8. Korum N, Ascii C, Yilmazlar T, Duman H, Zorluoglu A, Tuncel E, et al. Total thyroidectomy: changing trends in surgery. International Surgery. 1997;82:417-19.
9. 9. Mazzaferri EL. Mnagement of a solitary thyroid nodule. New England J Med. 1993;328:553-9.
10. 10. Vyas CS, Vijayvargiya SC, Porwal S, Gupta R, Swarnkar M. A study of thyroid swelling with clinicopathological parameteres. Int J Biological Med Res. 2013;4(2):3250-2.
11. 11. Jain S, Nayak R, Totade S, Shukla N. Study of Clinico-Pathological Correlation of Thyroid Swellings. IJMRR. 2014;2(6):554.
12. 12. Kamal MM, Arjune DG, Kulkarni HR. Comparative Study of Fine Needle Aspiration and Fine Needle Capillary Sampling of Thyroid Lesions. Acta Cytol. 2002;46(1):30-4.
13. 13. Sekhari T, Sankar JK, Bansal M. Role of different diagnostic modalities in the evaluation of solitary thyroid nodule; experience in tertiary referral centre of North India. IJNM. 2001;16(3):105-8.
14. 14. Silverman JF, West LR, Larkin EW, Park HK, Finley JL, Swanson MS, et al. The role of Fine needle aspiration Biopsy in the Rapid diagnosis and Management of thyroid Neoplasm. Cancer. 1986;57:1164-70.
15. 15. Dhanadia A, Shah H, Dave A. Ultrasonographic and FNAC correlation of thyroid lesions. Gujarat Med J. 2014;69(1):76.
16. 16. Borah KK, Medhi G, Sarma A. Thyroid Swelling – Evaluation by Ultrasonography with FNAC correlations. J Med Sci Clin Res. 2016;4:10089-99.
17. 17. Lokhande RB, Gedam BS, Shah Y, Kale V. The accuracy of ultrasonography and fine needle aspiration cytology in the diagnosis of nodular goitre: A prospective analysis of 42 cases. Int J Biomed Adv Res. 2015;6(01):43-6.