Abstract
The present study was undertaken to identify the complimentary role of high resolution ultrasonography and fine needle aspiration cytology (FNAC) in diagnosis of thyroid gland swelling pathology, also determine sensitivity, specificity and accuracy of both USG and FNAC and correlate it with histopathology report. Total 75 cases of thyroid swellings were evaluated in detail by taking history, doing clinical examination, USG, FNAC and histopathology. USG findings were correlated with the FNAC report. After thyroidectomy surgery, USG and FNAC results were followed up and correlated with histopathology report. Thyroid swellings were more common in the age group of 31–40 years (34.66%) with female preponderance 70(93.33%). According to USG diagnosis, most common benign thyroid swelling was multinodular goitre (37.33). Amongst all the thyroid swellings, on FNAC, 17(18.67%) cases were diagnosed as a malignancy. 12(16%) cases were of follicular carcinoma which was the most common in this study. The sensitivity, specificity and diagnostic accuracy of USG was 86.66%, 91.66% and 90.66% respectively whereas sensitivity, specificity and diagnostic accuracy of FNAC was 93.3%, 95% and 94.66% respectively. USG and FNAC are simple methods of diagnosing thyroid gland swellings. The sensitivity, specificity and diagnostic accuracy of USG and FNAC for thyroid gland swellings was reasonably good. USG followed by FNAC increases the accuracy to diagnose various thyroid swellings so by which unnecessary thyroid gland surgery and hence complications can be avoided. However the most accurate and confirmatory diagnosis is given by histopathology.
Keywords: Ultrasonography, Cytology, Thyroid gland, Histopathology, Goiter, Carcinoma
Introduction
Disorders of thyroid gland are amongst the most common endocrine and surgical problems encountered in clinical practice [1]. The incidence of thyroid diseases is increasing in recent years due to goitrogens and changing food habits. Thyroid gland is afflicted by various pathologies ranging from diffuse enlargement (goitre) to nodular lesions, thyroiditis, and malignancies [2]. High-resolution ultrasound has become the first line imaging modality for evaluation of the thyroid gland due to excellent visualization of the thyroid parenchyma. It is highly sensitive in detecting small nodules, calcification, septations and cysts as well as in guiding fine needle aspiration biopsies [3].
FNAC is a simple, quick, inexpensive method to detect thyroid swelling pathology. FNAC provides the most direct and specific information about thyroid. The use of FNAC reduces the number of thyroidectomies by approximately 50% [4, 5] which roughly doubles the surgical yield of carcinoma and reduces the overall cost of medical care in these patients by 25% [5]. FNAC may fail when the gland is too small or fibrotic and biopsy may be needed in such cases. FNAC may also fail in distinguishing between follicular adenoma and follicular carcinoma for which histopathology is necessary to distinguish between the two. USG and FNAC are commonly used cost effective methods of diagnosis; however there are drawbacks of each technique and the final answer to the problem is still elusive [6]. Ultrasonography and FNAC each have their own shortcomings but as their advantages outweigh the disadvantages, they should be routinely used for diagnosis of thyroid swelling pathology.
Thyroid surgery has many complications like haemorrhage, change in voice due to injury to recurrent laryngeal nerve, respiratory obstruction due to bilateral vocal cord palsy, laryngeal oedema, tracheal injury, thyroid storm, thyrotoxicosis, tetany due to injury to parathyroid glands etc. It is necessary to choose patients who genuinely need surgery especially in small thyroid swellings to avoid the risk of such dreadful complications. The purpose of present study was to find the sensitivity, specificity and accuracy of both USG and FNAC and correlate it with histopathology report so that unnecessary thyroid surgery and hence such dreadful complications can be avoided.
Materials and Methods
After obtaining Institutional Ethics Committee approval and valid informed consent from all the patients, this prospective observational study was carried out in the Department of ENT at Tertiary Care Hospital in rural area during a period of 2 years from November 2017 to October 2019. Total 75 patients of either sex, presented with clinically palpable and non-palpable thyroid swellings detected by USG, euthyroid patients with confirmed pathological lab reports, patients fit for general anaesthesia for thyroid surgery attending the outpatient department of ENT and admitted in ENT ward and who were operated for thyroidectomy after USG and FNAC diagnosis was confirmed were included in the study. Patients who had not given consent for FNAC and surgery, patients with bleeding diathesis, previously operated cases of thyroid malignancies were excluded from the study.
A detailed clinical history was taken; physical examination and investigations including thyroid function tests were done. The ultrasound examination of the thyroid gland was performed in real time 2D Grey scale and color Doppler modes using a high resolution, 7.5–12 MHz, linear array transducer of PHILLIPS 350 Ultrasound machine followed by FNAC of the thyroid swelling after performing a coagulation profile. The high resolution ultrasound findings were correlated with the FNAC report. After thyroidectomy surgery, USG and FNAC results were followed up and correlated with histopathology report.
Examination Technique
Both lobes of thyroid gland including isthmus were evaluated by PHILLIPS 350 machine unit using a 7.5–12 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. The region of carotid arteries and jugular veins laterally and supraclavicular fossa were also examined for any lymphadenopathy.
FNAC Technique
Before 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 a standard 1″ 25 gauge, noncutting bevelled edge needle. The needle was attached to a 10 ml syringe. After introducing the needle, the needle was moved gently but rapidly through the nodule center. Then gentle suction was done by putting the piston of the syringe. If the specimen contained much blood, aspiration was not done. In this, 25 gauge needle was inserted into the thyroid gland and no suction was applied and this needle was moved in back and forth excursions. The fluid of cells from the nodule moves into the needle due to capillary action. Such fluid specimen was less hemorrhagic. Two drops of the aspirate/fluid in the syringe were taken 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.
After seeing the USG and FNAC report, the patient was posted for thyroidectomy. The sample was sent for histopathology. USG and FNAC results were compared to histopathology of thyroid swelling.
Observations and Results
Total 75 patients with various thyroid swellings were enrolled in the study, among them 5 (6.66%) were males and 70 (93.33%) were females with male to female ratio of 1:14. The youngest patient was 18 years old and the eldest patient was 72 years old. The most common age group of patients with thyroid swellings in the present study was 31–40 years, (Table 1).
Table 1.
Distribution pattern of thyroid swellings according to age
| Age group (Years) | No. of patients | Percentage |
|---|---|---|
| 0–20 | 02 | 2.66 |
| 21–30 | 08 | 10.66 |
| 31–40 | 26 | 34.66 |
| 41–50 | 21 | 28 |
| 51–60 | 08 | 10.66 |
| 61–70 | 09 | 12 |
| 71–80 | 01 | 1.33 |
Majority of patients (37; 49.33%) presented with clinical complaints dating under 6 months and the majority i.e. 50(66.66%) of the cases were soft in consistency. Thyroid swelling was more common in right lobe (73.33%) as shown in Table 2. Both the right and left lobes were involved mostly in multinodular goitre, (Fig. 1b).
Table 2.
Distribution of cases according to duration of swelling, consistency and site of thyroid swellings
| Duration (Months) | No. of patients | Percentage |
|---|---|---|
| 0–6 | 37 | 49.33 |
| 7–12 | 14 | 18.66 |
| 13–24 | 06 | 8 |
| > 24 | 18 | 24 |
| Consistency | No. of patients | Percentage |
|---|---|---|
| Soft | 50 | 66.66 |
| Firm | 24 | 32 |
| Hard | 01 | 1.33 |
| Lesion | No. of patients | Percentage |
|---|---|---|
| Right lobe | 55 | 73.33 |
| Left lobe | 11 | 14.66 |
| Both lobes | 09 | 12 |
| Echogenecity | No. of patients | Percentage |
|---|---|---|
| Hypoechoic | 15 | 20 |
| Isoechoic | 16 | 21.33 |
| Hyperechoic | 39 | 52 |
| Heterogenous | 5 | 6.66 |
Fig. 1.
a USG of thyroid gland- right lobe is showing multiple cystic structures with moving echoes and calcification suggestive of colloidal goiter, b USG of thyroid gland- showing multiple nodules suggestive of multinodular goitre
According to ultrasonographic diagnosis, the most common benign thyroid swelling was multinodular goitre (37.33), (Fig. 1b) followed by colloid goitre (24%), (Fig. 1a) and 18(24%) cases were found to be a malignancy. On FNAC, most common benign thyroid swelling was colloid goitre (19; 25.33%), (Fig. 2a) followed by nodular goitre (18; 24%). Amongst all the thyroid swellings, on FNAC, 17(18.67%) cases were diagnosed as a malignancy. 12(16%) cases were of follicular carcinoma, (Fig. 3a) which was the most common in this study. Papillary carcinoma (Fig. 3b) was diagnosed in 5(6.67%) cases, (Table 3).
Fig. 2.
FNAC of thyroid swelling with smear showing a Colloid goiter, b Follicular neoplasm
Fig. 3.
Histopathological section of thyroid swelling showing a Follicular carcinoma and b Papillary carcinoma of thyroid gland
Table 3.
Distribution of cases according to USG and FNAC diagnosis
| USG diagnosis | No. of patients | Percentage | ||
|---|---|---|---|---|
| Benign | Non- inflammatory | Adenomatous | 05 | 6.66 |
| Multinodular | 28 | 37.33 | ||
| Colloidal | 18 | 24 | ||
| Inflammatory | Thyroiditis | 06 | 8 | |
| Malignant | – | – | 18 | 24 |
| FNAC diagnosis | No. of patients | Percentage | ||
|---|---|---|---|---|
| Benign | Non- inflammatory | Benign follicular nodule | 15 | 20 |
| Nodular goitre | 18 | 24 | ||
| Colloidal goitre | 19 | 25.33 | ||
| Inflammatory | Thyroiditis | 06 | 8 | |
| Malignant | Papillary carcinoma | 05 | 6.66 | |
| Follicular neoplasm | 12 | 16 | ||
Out of 75 cases, 57 were found to be benign on ultrasonography, of these 6 were diagnosed as inflammatory (thyroiditis) swellings and 51 were diagnosed as non-inflammatory benign swellings of thyroid gland whereas 58 cases were reported to be benign on FNAC which includes 6 cases of inflammatory (thyroiditis) and 52 of non-inflammatory swelling. According to USG, 18 cases were found to be of malignancy out of which 15 were confirmed as malignancy of thyroid gland by FNAC and 3 were benign on FNAC. Out of 57 benign swellings on USG, 55 were benign on FNAC and 2 were malignant, (Table 4).
Table 4.
Correlation of USG and FNAC diagnosis
| USG diagnosis | FNAC diagnosis | Total (USG) | |||
|---|---|---|---|---|---|
| Benign | Malignant | ||||
| Inflammatory | Non-Inflammatory | ||||
| Benign | Inflammatory | 6 | 0 | 0 | 57 |
| Non inflammatory | 0 | 49 | 2 | ||
| Malignant | 0 | 3 | 15 | 18 | |
| Total (FNAC) | 6 | 52 | 17 | 75 | |
| 58 | |||||
Out of the 18 thyroid swelling cases which were found to be a malignancy on USG, 13(true positive-TP) were found to be malignant on histopathology and 5(false positive-FP) were found to be benign on histopathology whereas out of 57 cases were found to be benign on USG, 2(False negative-FN) were found to be malignant on histopathology and 55(true negative-TN) were benign on histopathology. So the sensitivity of USG was 86.66% and specificity was 91.66%. The positive predictive value (PPV) of USG was 72.22% and negative predictive value (NPV) was 96.49%. Diagnostic accuracy of USG was 90.66%.
Out of 17 cases were diagnosed to be a malignant on FNAC, 14(true positive-TP) were found to be malignant on histopathology while 3(False positive-FP) were found to be benign. 58 cases were found to be benign on FNAC out of which, 1(False negative-FN) was found to be malignant on histopathology and 57(true negative-TN) were found to be benign on histopathology. The sensitivity of FNAC was 93.33% and specificity was 95%. The PPV was 82.23% while NPV was 98.27%. The diagnostic accuracy of FNAC was 94.66%, (Table 5).
Table 5.
Correlation of USG with Histopathology as well as correlation of FNAC with histopathology
| USG | Histopathology | Total | |
|---|---|---|---|
| Malignant | Benign | ||
| Malignant | 13 (TP) | 5 (FP) | 18 |
| Benign | 2 (FN) | 55 (TN) | 57 |
| Total | 15 | 60 | 75 |
| FNAC | Histopathology | Total | |
|---|---|---|---|
| Malignant | Benign | ||
| Malignant | 14 (TP) | 3 (FP) | 17 |
| Benign | 1 (FN) | 57 (TN) | 58 |
| Total | 15 | 60 | 75 |
Discussion
In the present study, ultrasonography was found to be useful in assessing the morphological structure of thyroid gland along with the gland size and helps in detecting impalpable swellings. It helps us to know clearly whether the lesion is solitary or multiple apart from the specific lobar involvement. Also, it helps to clearly differentiate between solid and cystic lesions. A total of 75 cases were studied among them most of the patients (34.66%) were in 31–40 years age group, the youngest being 18 years old and eldest 72 years old which is correlated with the other studies [1, 7–9]. Out of 75 cases, 5(6.66%) were males and 70(93.33%) were females with male to female ratio was 1:14. Prior studies [10–12] also yielded similar findings. So the thyroid lesions are more common in females in their active reproductive age group and are uncommon in postmenopausal age group. The possible reason for this is due to the presence of oestrogen receptors in thyroid gland in females. For the same reason, the level of thyroid hormones also changes according to the phase of menstruation. The majority of malignancies presented with symptoms of less than 6 months duration which is comparable with the study done by Jain et al. [13]. Most of the cases (66.66%) were soft in consistency while 34% cases were firm in consistency and only 1(1.33%) case was hard in consistency. 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 [14]. Right lobe preponderance was seen in this study and the majority of swellings which involved both lobes were of multinodular goiter which is accordance with the study done by Gupta et al. [2].
Out of 39 cases of hyperechogenecity, 37 are diagnosed as benign and 2 are diagnosed as malignant. Out of 16 isoechoic swellings, 15 were benign and 1 was malignant. 15 cases were of hypoechoic echogenicity out of which, 12 cases were diagnosed as malignant and 3 cases were diagnosed as benign. Out of 6 cases of thyroiditis, 1 was hypoechoic and 5 were heterogenous. These findings are correlated with the previous studies [11, 15] and in these studies hypoechogenecity was related with malignancy, hyperechoic with benign and heterogenecity was related with thyroiditis.
Eighteen cases were diagnosed as a malignancy on USG out of which 15 were reported as malignant on FNAC and 3 were reported as benign. 57 cases were diagnosed as benign on USG out of which, 2 were reported to be malignant while 55 were reported as benign on FNAC. These findings are accordance with the study done by Prasad et al. [11] and Avinash et al. [15]. Out of 18 cases diagnosed to be malignant on USG, 13 were reported as malignant and 5 were reported as benign on histopathology while out of 57 benign swellings diagnosed on USG, 2 were reported to be malignant and 45 were benign on histopathology which is comparable with the other studies [8, 9]. Seventeen cases were diagnosed to be malignant on FNAC, out of which 14 were reported to be a malignancy and 3 were reported to be benign on histopathology. Out of 58 benign swellings on FNAC, 1 was reported to be a malignancy and 57 were benign on histopathology. Similar finding is reported by Rathod et al. [1].
The sensitivity of USG was 86.66% while specificity was 91.66% whereas the positive predictive value (PPV) of USG was 72.22% and negative predictive value (NPV) was 96.49%. Diagnostic accuracy of USG was 90.66%. All these findings are comparable with earlier studies [8, 9]. However, sensitivity of FNAC was 93.3% while specificity was 95% while the positive predictive value (PPV) of FNAC was 82.23% and negative predictive value (NPV) was 98.27%. The diagnostic accuracy of FNAC was 94.66%. These results are in agreement with the other studies [1, 16, 17]. Thus due to high accuracy and high positive predictive value and negative predictive value of FNAC, it is a useful modality in diagnosing thyroid swelling pathology.
Conclusion
USG and FNAC are simple methods of diagnosing thyroid gland swellings. They can be performed as outpatient department procedures and are acceptable to most of the patients. They do not require anaesthesia and instant results are available. In the present study, the sensitivity, specificity and diagnostic accuracy of USG and FNAC for thyroid gland swellings was reasonably good. USG followed by FNAC increases the accuracy to diagnose various thyroid swellings so by which unnecessary thyroid gland surgery and hence complications can be avoided. However the most accurate and confirmatory diagnosis is given by histopathology.
Funding
Not Applicable
Compliance with Ethical Standard
Conflict of interest
The authors declare that there are no conflicts of interest regarding the publication of this paper.
Footnotes
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