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Cytology findings of the thyroid lesions with the histopathology findings correlation.

Introduction

Fine needle aspiration cytology (FNAC) is a well-known safe diagnostic procedure. FNAC is the study of cells collected by a fine needle under vacuum. This procedure has an advantage of being simple, safe, speedy, minimally invasive and cost effective. FNAC forms a valued assistant to the preoperative examination in the detection of thyroid nodules, and in majority of the cases, it can differentiate neoplastic from nonneoplastic lesions. [1] The ease and simplicity of the procedure and the diagnostic accuracy comparable with other invasive procedures have contributed greatly to the wide application of FNAC by most clinicians. [2] This technique has been successfully utilized in the diagnosis of many pathological lesions in multiple organs including lung, lymph nodes, bone, thyroid, salivary gland, soft tissue, and other anatomic regions such as head and neck, thorax, abdomen, and pelvis. [3,4] FNAC is a priceless, fast, practically noninvasive, and simple investigative procedure, the significance and applicability of which the clinicians and pathologists globally in recent time have progressively appreciated. [5]

Regarding the efficacy of FNAC, Stewart's statement regarding the aspiration biopsy is as appropriate as it was in 1933: "Diagnosis by aspiration is as reliable as the combined intelligence of the clinician and pathologist makes it." [6]

Considering the aforementioned importance of FNAC in modern cytological techniques, this work was undertaken to evaluate the FNAC of thyroid swellings from the patients approaching our institute in various surgical wards, and aspiration was done to perform the cytological diagnosis and postoperative histopathological correlation during the period from May 2011 to October 2013.

Materials and Methods

This prospective study was undertaken to study the cytology findings of palpable thyroid lesions and compare them with histology findings wherever possible to determine its diagnostic accuracy. All the patients referred to FNAC of thyroid lesions were studied prospectively for a period of 2 years from May 2011 to October 2013 in the Department of Pathology, Government Medical College, Surat, Gujarat, India. All the patients were clinically examined in detail, and a careful palpation of the thyroid was done to guide precisely the location for doing aspiration. The details of the procedure were explained to the patients and written consent of patients taken. Aspiration was done with the patient lying comfortably in a supine position, and neck was extended with a pillow under the shoulder so as to make the thyroid swelling appear prominent. Under aseptic precautions, 23-gauge needle was inserted into the lesion without attachment of a syringe and to and fro movement performed quickly. The material gets collected in the bore by capillary suction. The needle hub was attached to air-filled syringe, and the plunger was pushed down to expel the material onto a clean, labeled glass slide. Several smears were made in each case. Some samples were fixed in 95% ethyl alcohol and stained by routine hematoxylin and eosin (H&E) method and Pap smear method; other samples were air dried and stained with MGG stain.

During the period of this study from May 2011 to October 2013, a total of 485 FNAC done from thyroid; among them, 60 samples were biopsied subsequently and subjected to histopathological study. Only those cases with histopathological correlation were selected for this study. All the 60 patients were treated by surgeries such as total, subtotal, and hemithyroidectomies. Specimens for histopathological examinations were received in Pathology Department. All the specimens were fixed in 10% formalin. Detailed gross examination was done, and 4-10 tissue bits were selected from representative area for routine paraffin sections, which were stained by H&E method. Correlation of cytological and histopathological findings was performed. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were calculated for neoplastic and carcinomatous lesions by using the methodology of Galen and Gambino.

Results

A total of 60 cases were evaluated by cytology and histopathology examinations, which came to our Pathology Department. The majority of cases were female subjects, and female:male ratio was 9:1 [Table 1].

As shown in Figure 1, most of the cases were presented in the 31-50 years age group. Malignant lesions were found most commonly between 41 and 50 years age group [Figure 1].

The most common benign thyroid lesion in our study is colloid goitre [42 (70%) cases], second highest cases were of thyroiditis [7 (11.6%) cases], followed by follicular adenoma [3 (5%) cases]. The overall incidence of benign thyroid lesions was 93.3%. Most of the malignant lesions were seen in the 31-40 years and 41-50 years age group. In our study, the most common malignant thyroid lesion was papillary thyroid carcinoma [3 (5%) cases], and 1 (1.6%) case was of anaplastic carcinoma. The overall incidence of malignant thyroid lesions was 6.6% [Table 2].

Overall accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of FNAC in diagnosis of both benign and malignant lesions were 95%, 87.5%, 96.15%, 77.77%, and 98.03%, respectively.

Discussion

FNAC is now established as a valuable, safe, and expedite test in the diagnostic management of various thyroid diseases. The technique is safe, simple, and quick with a low complication rate. FNAC is usually the first line of diagnosis, and other investigations such as ultrasonography examination, thyroid function tests, thyroid scan, and antibody levels are performed consequently with an aim to choose the patients who warrant surgery and those who can be managed conservatively. [7,8]

In our study, the age of the participants ranges from 6 month to 80 years, with median of 43 years, which is comparable with the studies done by Knatasueb et al., [9] Gupta et al., [10] and Patel. [7] We found that female subjects were commonly affected and male to female ratio was 1:9 in our study; similar female preponderance was found in the studies done by Patel [7] and Unnikrishnan and Menon [11] The most common cytological diagnosis was colloid goitre (70%) in this study. Similar findings were observed by Patel. [7] In our study, the overall reported benign thyroid lesion was 93.3% and malignant lesion was 6.6%, which was comparable with those reported in the study by Kantasueb et al. [6-11] Goitre is one of the most common types of thyroid lesion in developing countries. Other diagnosis observed are thyroiditis [7 (11.6%) cases], follicular adenoma [3 (5%) cases], thyroglossal cyst [2 (3.3%) cases], benign cystic lesion [1 (1.6%) case], hyalinizing trabecular tumor [1 (1.6%) case]. In this study, the most common malignant thyroid lesion was papillary thyroid carcinoma [3 (5%) cases], and 1 (1.6%) case was of anaplastic carcinoma.

The analysis of FNAC results after the histopathological examination of postoperative tissue showed sensitivity, specificity, positive predictive value, and negative predictive value as follows: 87.5%, 96.15%, 77.77%, and 98.03%, respectively. These results are also comparable with the results obtained by other studies [Table 3]. In nonneoplastic lesions, i.e., colloid goitres, of 38 cases, 37 were histopathologically correct and one was incorrect, which was diagnosed later as follicular adenoma. In benign cystic lesions, the one case was corrected with histological findings. In thyroiditis, of the eight cases, seven were correct and one was incorrect, which case was diagnosed as colloid goitre instead of thyroiditis in histology examination. The neoplastic benign lesions included four cases of follicular neoplasm. These four cases of follicular neoplasm were diagnosed as follicular adenoma, insular variant of papillary carcinoma, hyalinizing trabecular tumor, and nodular goitre, with each one case.

In the cases of malignant lesions, three cases were of papillary carcinoma; of these, two cases were correlated with histopathological examination and one case of anaplastic carcinoma was corrected with histological findings. In this study, two cases were diagnosed as thyroglossal cyst by FNAC, which were confirmed by histopathological examination [Table 2].

Conclusion

The efficacy of FNAC for diagnosing thyroid lesions (benign versus malignant) in our institute was quite reliable. We showed high specificity > 95% with high negative predictive value (98.03%), which meant there was a low false negative rate, showing the efficacy of FNAC. We showed >85% sensitivity and 77.77% positive predictive value; so, there is more than 10% chance of being falsely (false positive rate) diagnosed as positive. However, the causes of rather false positive rates should be identified to improve the efficacy of FNAC in the future.

DOI: 10.5455/ijmsph.2016.1607201596

References

[1.] Sinna EA, Ezzat N. Diagnostic accuracy of fine needle aspiration cytology in thyroid lesions. J Egypt Natl Canc Inst 2012; 24(2): 63-70.

[2.] Linsk JA, Franzen S. Clinical Aspiration Cytology. 2nd edn. Philadelphia, PA: JB Lippincott, 1983. pp. 8-104.

[3.] Leopold G, Koss MD. Diagnostic Cytology and Its Histopathologic Bases. 4th edn. Philadelphia, PA: Lippincott JB, 1992. pp. 395-476.

[4.] Kline TS. Handbook of Fine Needle Aspiration Cytology. 2nd edn. Edinburg: Churchill Livingstone, 1988. pp. 200-48.

[5.] Bagga PK, Mahajan NC. Fine needle aspiration cytology of thyroid swellings: how useful and accurate is it? Indian J Cancer 2015; 47(4):437-42.

[6.] Bawankule N, Nishant S. Cytohistopathological correlation relation of head neck and face lesions. Int J Recent Trends Sci Technol 2015; 15:81-6.

[7.] Patel MM. Fine needle aspiration cytology as a first line investigation in thyroid lesions. Natl J Med Res 2013; 3(2):106-10.

[8.] Parikh UR, Goswami HM, Shah AM, Mehta NP, Gonsai RN. Fine needle aspiration cytology (FNAC) study of thyroid lesions (study of 240 cases). Gujarat Med J 2012; 67(2):25-30.

[9.] Kantasueb S, Sukpan K, Mahanupab P. The study of thyroid lesions and the correlation between histopathological and cytological findings at Maharaj Nakorn Chiang Mai Hospital between 2003 and 2007. Chiang Mai Med J 2010; 49:105-10.

[10.] Gupta M, Gupta S, Gupta VB. Correlation of fine needle aspiration cytology with histopathology in the diagnosis of solitary thyroid nodule. J Thyroid Res 2010; 2010:379051.

[11.] Unnikrishnan A, Menon U. Thyroid disorders in India: an epidemiological perspective. Indian J Endocrinol Metab 2011; 15(Suppl 2):S78-81.

[12.] Muratli A, Erdogan N, Sevim S, Unal I, Akyuz S. Diagnostic efficacy and importance of fine-needle aspiration cytology of thyroid nodules. J Cytol 2014; 31(2):73-8.

Rasik Hathila (1), Sharmishtha Patel (1), Piyush Vaghela (1), Gopal Makwana (1), Piyush Parmar (2)

(1) Department of Pathology, Government Medical College, Surat, Gujarat, India.

(2) Department of Community Medicine, Government Medical College, Surat, Gujarat, India.

Correspondence to: Gopal Makwana, E-mail: drgopal111@yahoo.com

Received July 16, 2015. Accepted August 27, 2015
Table 1: Comparison of result of thyroid test between FNAC
and histopathology findings

Diagnosis                         FNAC, n (%)   Histodiagnosis, n (%)

Benign lesions
  Colloid goiter                   38 (63.3)          42 (70)
  Benign thyroid cyst               1 (1.6)            1 (1.6)
  Thyroglossal cyst                 2 (3.3)            2 (3.3)
  Follicular adenoma                  --               3 (5.0)
  Hashimoto's thyroiditis           7 (11.6)           6 (10.0)
  Lymphocytic thyroiditis           1 (63.3)           1 (1.6)
  Hyalinising trabecular tumour       --               1 (1.6)
  Other                             2 (3.3)              --
  Total                            51 (85.0)          56 (93.3)
Malignant lesions
  Papillary carcinoma               3 (5.0)            3 (5.0)
  Anaplastic carcinoma              1 (1.6)            1 (1.6)
  Other                             5 (8.3)              --
  Total                             9 (15.0)           4 (6.6)

Table 2: Correlation between cytodiagnosis and histodiagnosis

Cytological diagnosis     Histological diagnosis    No. of  Remarks
                                                    cases

Colloid goiter            Colloid goiter              3
Benign cystic lesion      Benign cystic lesion        1
Diffuse toxic goiter      Colloid goiter              2
Hashimoto's thyroiditis   Hashimoto's thyroiditis     6     True
                                                            negative,
                                                            total = 50

Lymphocytic thyroiditis   Lymphocytic thyroiditis     1
Thyroglossal cyst         Thyroglossal cyst           2
Thyroiditis               Colloid goiter              1
Follicular neoplasm       Follicular adenoma          1
                          Hyalinizing trabecular      1
                            tumor
Papillary carcinoma       Insular variant of          1     True
                            papillary carcinoma             positive,
                                                            total = 7
                          Papillary carcinoma         2
Possibility of            Follicular adenoma          1
  Medullary carcinoma
Anaplastic carcinoma      Anaplastic carcinoma        1
Possibility of            Nodular goiter              1     False
  Papillary
  carcinoma                                                 positive,
                                                            total = 2
Follicular neoplasm       Nodular goiter              1
Adenomatous goiter        Follicular adenoma          1     False
                                                            negative,
                                                            total = 1

Table 3: Comparison of diagnostic value for neoplastic lesions

Parameters                   Muratli et     Kantasueb et
                             al. [12] (%)   al. [9] (%)

Accuracy                         77.3          88.40
Sensitivity                      87.1           74.7
Specificity                      64.6          93.22
Positive predictive value        76.1          79.49
Negative predictive value        79.5          91.29

Parameters                   Bagga and Mahajan     This
                                  [5] (%)        study (%)

Accuracy                           96.2             95
Sensitivity                         66             87.5
Specificity                         100            96.15
Positive predictive value           100            77.77
Negative predictive value           96             98.03

Figure 1: Age-wise distribution of thyroid lesion.

        Non neoplastic     Non neoplastic   Neoplastic benign
        non inflammatory   inflammatory     Lesions
        lesions

1-10          3
11-20         1
21-30         10
31-40         9                 3
41-50         9                 2                3
51-60         9                 1
61-70         4
71-80                           1

           Neoplastic

1-10
11-20
21-30          1
31-40          1
41-50          2
51-60
61-70
71-80

Note: Table made from bar graph.
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Article Details
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Title Annotation:Research Article
Author:Hathila, Rasik; Patel, Sharmishtha; Vaghela, Piyush; Makwana, Gopal; Parmar, Piyush
Publication:International Journal of Medical Science and Public Health
Article Type:Clinical report
Geographic Code:9INDI
Date:Apr 1, 2016
Words:2097
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