|Year : 2020 | Volume
| Issue : 2 | Page : 201-204
Proportion of malignancy in solitary thyroid nodule
Rajan Kumar, J Hitesh
Department of General Surgery, Calicut Medical College, Kozhikode, Kerala, India
|Date of Submission||08-Aug-2020|
|Date of Decision||13-Aug-2020|
|Date of Acceptance||14-Oct-2020|
|Date of Web Publication||07-Nov-2020|
Dr. J Hitesh
Department of General Surgery, Calicut Medical College, Kozhikode, Kerala
Source of Support: None, Conflict of Interest: None
Introduction: Solitary nodule of thyroid (SNT) is a common diagnostic challenge, as it may be malignancy. Investigations are essential to establish functional status and cytopathological nature. Fine-needle aspiration cytology (FNAC) is very important. The incidence of malignancy in SNT is approximately 40%. Hence, early diagnosis is necessary for adequate treatment. This study focuses on the incidence of malignancy in SNT and study of different histopathological types. Materials and Methods: An observational study was conducted on 200 patients with solitary thyroid nodule and followed up with imaging, FNAC, intraoperative findings and histopathological report. Results: There was a female preponderance (139; 69.5%), and majority were between 4th and 5th decades of life (55.2%). The Mean age of at presentation was 47 years. The proportion of malignancy in SNT revealed by histopathological examination in this study was 36%. Out of which females are having 46 out of 139 that is 33% were malignant. In males 25 out of 61, means 40% were malignant. In females, out of the 46 cases, 16 (34%) had follicular carcinoma and 30 (65%) papillary carcinoma. In males, out of 25 cases follicular carcinoma comprised 9 (36%) and papillary carcinoma comprised 46 (64%) cases. Conclusions: The risk of malignancy in SNT was significant. Malignancy was more predominant in males. Papillary carcinoma represented more number of cases than follicular carcinoma. Malignancy was mostly present as hard nodules. There was no significant association with size of nodule and pattern of malignancy. Lymph node involvement was more with papillary carcinoma. The solitary nodules involved the left side of the thyroid more commonly than the right.
Keywords: Follicular, papillary, solitary nodule thyroid
|How to cite this article:|
Kumar R, Hitesh J. Proportion of malignancy in solitary thyroid nodule. Kerala Surg J 2020;26:201-4
| Introduction|| |
A discrete swelling in an otherwise impalpable gland is termed solitary nodule of thyroid (SNT) gland. Thyroid nodular disorders are relatively common among adults, with an overall prevalence of approximately 4%–7% in the general population. Factors such as age, sex, diet, iodine deficiency and even therapeutic and environmental radiation exposure depend on the prevalence of thyroid disease. The prevalence increases with age, with spontaneous nodules occurring at a rate of 0%–0.8% in a year, starts early in life and extending into the eighth decade., True solitary thyroid nodules (STNs) occur in 4%–7% of the adult population. They are observed in 5% of persons at an average age of 60 years. They are seen more common in females (6.4%) compared to males (1.5%), and this trend exists throughout all age groups. Currently, even though there are many investigations such as diagnostic imaging studies, serologic and cytogenetic tests as well as histopathological techniques are available to evaluate STN. Among these investigations, fine-needle aspiration cytology (FNAC) has become the diagnostic tool of choice for the initial evaluation of STN.
| Materials and Methods|| |
This study was intended to determine the proportion of malignancy in solitary thyroid nodule (STN) in a government hospital using histopathological examination (HPE) and to study the different histopathological types of malignancy in STN. We did a descriptive observational study of 200 surgically treated cases above the age of 13 years admitted for clinical STN were evaluated by clinical, ultrasonological and intraoperative findings. Patients having other head and neck malignancies, patients with recurrent thyroid swelling and patients with diffusely enlarged thyroid gland clinically or multiple nodules clinically were excluded. HPE reports of thyroid malignancy were assessed. The study tools were case sheets of patients and histopathological reports. Microsoft Excel and Word 2007 were used for data entry and SPSS 18 software was used for data analysis.
| Results|| |
Analysis of FNAC results showed that 14 (7%) were non-diagnostic, 122 (61%) benign, 6 (3%) had atypical cells, 33 (16.5%) were suspicious of follicular neoplasm, 22 (11%) suspicious of malignancy and 3 (1.5%) were malignant [Figure 1].
|Figure 1: Analysis of fine-needle aspiration cytology in the study population|
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During surgery, 178 (89%) had no infiltration to strap muscles and 22 (11%) had infiltration to adjacent structures.
Analysis of results of HPE in the study population showed that 128 (64%) were benign, 46 (23%) were papillary carcinoma and 26 (13%) were follicular carcinoma [Figure 2]. The proportion of malignancy in the clinical SNT cases, 64 (36%) out of 200 were malignant in postoperative HPE report.
|Figure 2: Analysis of histopathological examination in the study population|
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Comparison of sex in the HPE in the study population showed that out of the 128 cases of colloid nodules, 87 (67.97%) were female and 41 (32.03%) male. The 26 follicular carcinoma cases comprised 19 (73.08%) females and 7 (26.92%) males. Of the 46 papillary carcinoma cases, 33 (71.74%) were female and 13 (28.26%) male. The details are depicted in [Figure 3].
|Figure 3: Comparison of sex and histopathological examination in the study population|
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Comparison of size of nodule and HPE in the study population showed that most benign cases were seen at a range of size 2 cm to 4 cm, more at 3 cm. Most of the malignant cases were in the 2 cm to 4 cm range or more than 4 cm [Table 1]. Consistency of the nodules was either variable or firm. Malignancy was more in variable consistency nodules [Table 2].
On comparing between cervical LN and HPE in the study population, out of the 128 cases of benign nodule, all were lymph node negative. Out of the 26 follicular carcinoma cases, 25 (96.15%) were node negative and 1 (3.85%) was positive. Out of 46 cases of papillary carcinoma, 40 (86.96%) were node negative and 6 (13.04%) node positive.
Descriptive comparison between site of nodule and HPE in the study population showed that majority (128 cases) were in the left lobe, of which 70 (54.69%) were benign, 23 (50%) papillary carcinoma and 17 (65.38%) follicular carcinoma. Of the 49 cases in the right lobe, 49 (38.28%) were benign, 17 17 (36.96%) were papillary carcinoma and 8 (30.77%) follicular carcinoma. Of the 16 cases in the isthmus, 9 (7.03%) were benign, 6 (13.04%) were papillary carcinoma and 1 (3.85%) was follicular carcinoma [Figure 4].
On comparing the FNAC finding and the HPE report in the study population, it was seen that out of the 200 cases, 122 (61%) were colloid adenomas, 33 (16.5%) were follicular neoplasm and 22 (11%) were papillary carcinoma. The sensitivity and specificity of FNAC for neoplasm detection were 73.9% and 80.0%, respectively.
Out of 122 colloid nodules in FNAC, 11 (9.1%) cases turned out to be malignancy. Among 6 cases with atypical cells in FNAC, 4 (66.6%) case turned into malignancy, in about 33 cases of suspicious follicular neoplasm in FNAC 32 (96.9) cases turned into malignancy 76. Out of 22 cases with suspected malignant cells in FNAC, 20 (90%) were malignant in post-operative HPE. Among 3 cases of Bethesda Category 6, all 3 (100%) cases turned out to be malignancy [Table 3]. The mean age for colloid nodule was 43.84 years, for follicular carcinoma 43.06 years and for papillary carcinoma 40.88 years. The ultrasound size for colloid nodule was 3.53 cm, follicular carcinoma 3.47 cm and papillary carcinoma 3.56 cm.
| Discussion|| |
Out of 200 cases, there was a female preponderance (139; 69.5%) and majority were between 4th and 5th decades of life (50.4%). The mean age at presentation was 47 years. In a study by Khan et al., majority were female, but the age range was mostly in 20–39 years, noting a change in age distribution from our study.
The proportion of malignancy in SNT revealed by HPE in this study was 36%, out of which females were 46 out of 139 and 33% were malignant. In males, 25 out of 61 (40%) were malignant. In a study of malignancy in solitary thyroid nodule by Jena et al., a proportion of 40% was observed. In a study on “pattern of malignancy in clinically solitary thyroid” by Khan et al., malignancy was more predominant in males (25.00%) than in females (14.47%) in STN. This difference may be due to genetic and environmental factors and to the methods employed in the study.
In females, out of the 46 malignancies, 16 (34%) had follicular carcinoma and 30 (65%) papillary carcinoma. In males, out of 25 cases of malignancy, follicular carcinoma comprised 9 (36%) and papillary 16 (64%) cases. Almost similar result is reported in a study by Khan et al. In this study, 12 (63.16%) were papillary carcinoma and 5 (26.31%) were follicular carcinoma.
Out of the 200 cases, 74 were over the right lobe, 110 over the left lobe and 16 over the isthmus. This is not comparable with the study by Khadilkar and Maji. They reported that solitary nodules were more on the right side than the left. Solitary nodule was present in about 60% in the right lobe and 32% in the left lobe. However, in the present study, it had been observed that left side was more common compared to the right side.
In our study, no benign nodule or follicular carcinoma was infiltrating to adjacent structures, but 22 out of 46 cases of papillary carcinoma showed infiltration. This compares with the study by Khadilkar and Maji., where papillary carcinoma showed more infiltration (40%) than follicular carcinoma (10%).
FNAC of the 200 cases in the present study showed 122 (61%) as colloid nodules, 33 (16.5%) as follicular neoplasm and 22 (11%) as papillary carcinoma. Fine-needle aspiration was diagnostically useful in about 80% of cases reported by Hegedüs  as also comparable with Keh et al. The sensitivity and specificity of FNAC for neoplasm detection were 73.9% and 80.0%, respectively.
There was no significant association with size of nodule and pattern of malignancy in the study by Khan et al. In the present study also, there was no significant association between size of nodule and pattern of malignancy.
| Conclusions|| |
The risk of malignancy in SNT was quite significant. Malignancy was more predominant in male papillary carcinoma represents more number of cases than follicular carcinoma. Malignancy was mostly present as hard nodules. There was no significant association with size of nodule and pattern of malignancy. Lymph node involvement was more with papillary carcinoma. The solitary nodules involved the left side of the thyroid more commonly than the right. Papillary carcinoma showed more infiltration than follicular carcinoma. Trends of benign nodule in preoperative diagnosis turning into malignancy in postoperative HPE was 13%.
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Conflicts of interest
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3]