Study of 140 Thyroidectomy Patients to Find Out the Incidence of Thyroid Malignancy in Thyroid Swelling

Introduction

Bangladesh especially North Bengal area is an endemic zone for iodine deficiency goitre and most of the patient of this study are from this endemic area. They present as visible neck swelling which moves on deglutition. Any patient presented with thyroid swelling are routinely investigated for ultra-sonogram of the thyroid gland, serum TSH and FNAC. Final diagnosis requires morphological examination for which histopathological examination becomes mandatory test [1]. In 1870 Rugu and his associate Joham Vent have first advocated surgical biopsy as an essential tool [2]. The diagnostic method of FNAC was first published in 1883 by Leyden. But the diagnosis of thyroid swellings using aspiration cytology was first reported by Martin and Ellis in 1930. FNAC, however has limitation related to specimen adequacy, sampling techniques, skill of performing the procedure, interpretation of the aspirate, overlapping cytological features between benign and malignant follicular neoplasm and also in the detection of some papillary carcinoma associated with other pathology like multinodular goitre, cystic changes [3, 4, 5]. Mundasad, et al. had done a comparative study between FNAC and histopathology and founded that FNAC had a sensitivity (52.6%), specificity (86.6%) and accuracy (79.1%) for thyroid malignancy [6].

Materials and Methods

This cross sectional study was done among patients undergoing thyroidectomy between January 2016 to July 2019 at Matin Specialized Hospital, Bogura, Bangladesh. The patients were selected consequently as and when they presented during the study period considering inclusion and exclusion criterias. The selected patients were examined clinically and routine ultra sonography, Matin MA, et al. Study of 140 Thyroidectomy Patients to Find Out the Incidence of Thyroid Malignancy in Thyroid Swelling. Otolaryngol Open Access J 2019, 4(2): 000185.

TSH, FNAC, routine haematological investigations, Chest X-ray ECG, CT scan if indicated were done. All patients FNACs were done by a single senior cytologist. All surgeries were done by the single principal Author and all thyroidectomies specimens were examined by one senior histopathologist.

Results

The age of the patients ranged from 6 to 70 years with a mean age 38.66 years (Table 1). The thyroid lesions were more common in females than male in a ratio of 3.66:1. Tables 2 & 3 shows FNAC findings of 140 cases where 115 are benign and 25 cases are malignant lesion with benign malignant ratio is 4.6:1. Among the benign lesions the most common lesion is multi nodular or colloid goiter. Table 4 shows out of 25 malignant cases of FNAC finding, 92% is papillary carcinoma. Histopathological examinations of all 140 thyroidectomy specimens showed 85 cases (60.71%) are colloid goiter and 40 cases (28.57%) are papillary carcinoma (Tables 5 & 6) shows incidence of benign and malignant lesions among 140 specimens. There are 94 (67.14%) benign lesions and 46 (32.85%) malignant lesions, so approximately benign and malignant ratio is about 2:1 which is very worrying. Finally among the thyroid cancer about 91% is papillary carcinoma Table 7.

Copyright© Matin MA, et al.

Matin MA, et al. Study of 140 Thyroidectomy Patients to Find Out the Incidence of Thyroid Malignancy in Thyroid Swelling. Otolaryngol Open Access J 2019, 4(2): 000185.

The incidence of thyroid cancer has rapidly increased in the United States (US) and other developed countries over the past 30 years [7]. Although some researchers believe this is a true increase in thyroid cancer, [8] but this increase is due to better diagnostic testing such as ultrasonography and fine-needle aspiration biopsy, resulting in the detection of disease that is unlikely to cause symptoms or death of the patient [9].

Other countries have seen similar increases in thyroid cancer. From 1993 to 2011, South Korea witnessed a 15- fold increase in thyroid cancer with nearly the entire increase attributed to papillary cancers [10]. Davies and Welch also showed, using the SEER program and data, that the rates of follicular, medullary and anaplastic thyroid cancers show no significant change from 1973 to 2002 [11]. Our study also found similar result of increasing incidence of thyroid cancer and most of which are papillary carcinoma. The most important part of our study is limitation of FNAC which includes false negative result and false positive results. Sikder had done accuracy of fine needle aspiration cytology and had found that accuracy was 90% and sensitivity was 68.75% [12]. Bloch had done a comparison study between FNAC and histopathology and had found accuracy of FNAC was 91.6% [13]. In our study false positive was 7 and false negative was 23 out of 140 thyroidectomy patients and overall sensitivity were 41%, specificity 93%, PPV 69.56% and NPV 80.17%.

Copyright© Matin MA, et al.

Conclusion

As the incidence of thyroid cancer is increased over the last decade it is also increased in Bangladesh. Our study observed 32.85% cases are thyroid cancer among the thyroid swelling underwent thyroid surgery. Ultrasonography and FNAC are both essential diagnostic tool for thyroid swelling but final diagnosis to rule out thyroid cancer is surgical excision and biopsy. In our study benign to malignant ratio is about 2:1 so FNAC proven benign lesions should not left untreated.