Histomorphological Patterns of Lesions in Thyroid Specimens

Background: The thyroid gland is an important endocrine organ required for the regulation of the basal metabolic rate. It also plays a very important role in growth. Thyroid disorders have great importance because most thyroid diseases are curable. In any area, thyroid gland disorders have a variable incidence and prevalence depending upon several factors. The objective of the study is to find out the relation of age and gender with the frequency of various thyroid lesions. Material and Methods: It was a descriptive, cross-sectional study carried out on thyroidectomy specimens received at histopathology laboratory of Holy Family Hospital, Rawalpindi. From January 2015 to June 2018, 242 thyroidectomy specimens were selected based on non-probability consecutive sampling. Reports with no clearcut definitive diagnosis were excluded. Data were analyzed using SPSS 22. Results: In our study of 242 thyroidectomy specimens, patients age ranged from 4 to 70 years. 40 to 49 years was the peak age and the mean age was 37.1 years. The female to male ratio was 6.4:1. From 242 cases, 18(7.4%) were neoplastic thyroid lesions and 224(92.6%) were non-neoplastic ones. Hyperplastic lesions were the most common in our study. The frequency of the inflammatory lesion was 4.1% with Hashimoto thyroiditis (80%) being the most common. The frequency of benign neoplasm was 2.1%. A follicular adenoma was the only benign thyroid neoplasm in our study. The frequency of malignant neoplasm was 5.4%. The most common subtype of thyroid malignancy was papillary thyroid carcinoma (76.9% of the malignant cases). Among a total of 242 cases, 83.1%(n=201) patients had only one presenting complaint (neck swelling). Conclusion: Thyroid disorders are more common in females compared to males. The hyperplastic lesion is the most common type seen. In this study, the most common benign neoplasm is follicular adenoma and the most common malignant neoplasm is papillary carcinoma. Neck swelling is the commonest presenting complaint in our study participants.


Introduction
The thyroid gland is present in the anterior neck consisting of two lateral lobes connected by the isthmus that lies anterior to C2 to C4. It is an important endocrine organ, which produces several hormones with thyroxine (T4), triiodothyronine (T3), and calcitonin being the dominant ones. 1,2,3 Thyroid diseases have great importance because these are curable in nature. There is variation in incidence and prevalence of thyroid disorders in any given area depending upon many factors like age, gender, and geographical characteristics of the area. In women, thyroid diseases are 5 to 7 times more common than in men. 4,5 Moreover, thyroid diseases are more prevalent in areas that are deficient in iodine. 15 Common pathologies of thyroid encountered are hyperthyroidism, hypothyroidism, and neoplasms. 3 Most of the thyroid nodules are due to cystic changes in nodular goiter or colloid cyst while a few of the solitary nodules are neoplastic. Goiter is the most common manifestation of thyroid disease worldwide occurring in 3% to 5% of the population. 4,6 In neoplastic nodules, adenoma of the thyroid is the most common benign tumor. 9 Thyroid lesions persisting for more than five to seven years may lead to thyroid carcinoma. Thyroid carcinomas consist of 1 to 2% of all carcinomas worldwide. 6 Also, carcinoma of the thyroid is among the most common endocrine malignancies. 9 Papillary carcinoma (81.3%) is the most common thyroid carcinoma followed by follicular (6.3%), medullary (6.3%), and anaplastic carcinoma (6.3%). 8 Metastasis has been reported to be very low in the thyroid gland (0.14%). 10 In thyroid lesion, diagnosis depends upon thorough clinical examination with thyroid function tests (TFTs) and radiological examination followed by histopathological examination for the definitive diagnosis. Extensive research is required at large scale to determine common types of thyroid gland lesions prevalent in our region. This will not only add to the body of existing knowledge but also ensure effective management strategies. The aim of this study is to find the relation of age and gender with the frequency of various thyroid lesions.

Materials and Methods
It was a descriptive, cross-sectional Study of thyroidectomy specimens received at Histopathology Laboratory of Holy family Hospital, Rawalpindi. From January 2015 to June 2018, 242 thyroid specimens were selected based on non-probability consecutive sampling. The specimens were formalin fixed, paraffin embedded and stained with hematoxylin and eosin. The slides were analyzed by taking into account all the clinical details. All the patients who underwent any kind of thyroid surgery were included. Reports with no clear-cut definitive diagnosis were excluded. Detailed information regarding age, gender, presenting complaint and histopathological diagnosis was obtained from histopathology request forms and register. All demographic and laboratory data were recorded on a proforma. Sample size was calculated by using WHO sample size calculator. Data were analyzed by using SPSS version 22. For categorical variables, frequency tables were made, and chi square test was applied to find out the relation of age and gender with particular type of thyroid lesions.

Results
From January 2015 to June 2018, 242 thyroidectomy specimens were received. 209 (86.4%) specimens were of females and 33 (13.6%) were of males. The male to female ratio was 1:6.4 as shown in the pie chart below ( Figure 2). Patients had an age from 4 to 70 years. 37.1 years was the mean age and 30 to 49 years was the peak age group as depicted in the graph below.  To determine the relation of gender and thyroid lesion, a chi-square test was applied. We tested the hypothesis "There is no association among female gender and thyroid lesion" against the alternative "There is association among female gender and thyroid lesion" at a 0.05 level of significance. The results were X2 =242, df=1 and p-value=0.000. As the p-value was less than 0.05, we rejected our null hypothesis of absence of association between female gender and thyroid lesion. (Table 1)  To determine the relation of age and thyroid lesion, we applied a chi-square test. We tested the hypothesis "There is no association among age group ranged from 30 to 49 years and thyroid lesion" against the alternative "There is association among age ranging from 30 to 49 years and thyroid lesion" at a 0.05 level of significance. The results were X2 =242, df=1 and p-value=0.000. As the p-value was less than 0.05, we rejected null hypothesis of absence of association between age ranging from 30 to 49 years and thyroid lesion. (Table 2)  Table 3. In our study, there was no case of lymphoma, follicular, and medullary carcinoma.   (Table 5). This is probably because most of the hyperplastic and neoplastic lesions are common in this age group. So, the load of thyroid lesions is tilted towards this age group.  Hyperplastic thyroid lesion (86.4%) was the most common thyroid lesion in our study. It is also the most common thyroid lesion in the studies conducted by Albasri et al 11 and Haque et al 14 as shown in Table 7. Female: male ratio is 6.6:1.  Table 8. The most common inflammatory lesion was Hashimoto thyroiditis (80%). Most of the patient had age from 30-49 years. Female to male ratio was 9:1.

Conclusion
In our study, neoplastic lesions are much less as compared to non-neoplastic ones. Most of the patients have a hyperplastic lesion. Among benign neoplasm, follicular adenoma is the most common and among malignant neoplasm, papillary carcinoma is the most common carcinoma. Overall, diseases of thyroid are more common in females as compared to males.

Recommendations
Thyroid carcinoma is not rare. The clinical and radiological examination followed by a histopathological diagnosis of every patient presenting with neck swelling is necessary to rule out thyroid carcinoma. To decrease the incidence of thyroid lesions in the areas having iodine deficiency, appropriate steps should be taken. The results of this study may be considered as baseline data of thyroid lesions in Rawalpindi. Large scale study is required to find out the exact frequency of thyroid diseases in our country so that a proper plan can be established for early diagnosis and management.