HISTOPATHOLOGICAL SPECTRUM OF THYROID LESIONS AT TERTIARY CARE HOSPITAL IN WESTERN RAJASTHAN

Objective: The objective of the study is to determine the proportion of different patterns (colloid goiter, colloid cyst, papillary carcinoma, etc.) of thyroid lesions among the patients who have undergone surgical treatment. Methods: This was prospective and retrospective study to be conducted on 100 thyroidectomy specimens received in 5-year period (2016–2020) in Department of Pathology in Dr. S.N. Medical College, Jodhpur. Results: Age ranged from 10 days to 85-year-old, Peak incidence of thyroid diseases was seen in the third to fifth decade, 78% non-neoplastic lesion, Adenomatous goiter was the most common non-neoplastic lesion (65%), Papillary carcinoma was the most common malignant lesion encountered. Conclusion: Although non-invasive techniques like aspiration cytology provide a diagnosis in most, the ultimate answer often rests with histopathological examination of thyroidectomies, which forms the mainstay for a definitive diagnosis. Thorough gross and microscopic evaluation of thyroidectomies is mandatory even for non-neoplastic lesions as they sometimes harbor neoplasms.


INTRODUCTION
The thyroid gland is present in the neck which is enclosed by the pretracheal fascia.The pretracheal fascia is a part of the deep cervical fascia.It is located in front of the 2 nd , 3 rd , and 4 th tracheal rings and weighs around 20-25 g [1].Thyroid glands have a variety of diseases that range from functional and immunological mediated enlargement to neoplastic lesions.Thyroid gland lesions vary in their incidence and histopathological patterns.They may also differ in terms of geographical area, age, sex, dietary, and environmental factors [2].Around 42 million people are affected by thyroid diseases in India [3].Clinically visible thyroid nodules are present around 4-5% of population [4].
Autoimmune thyroid disease is more common than iodine deficiency, as a cause of goiter in areas with sufficient iodine.Thyroid carcinoma closely resembles its benign counterpart in physical characteristics, measurable physiological parameters such as serum T3/T4 levels and ultrasonic characteristics.Therefore, the surgical excision of the nodule and its histological examination is the only way to differentiate between the more frequent benign and much less frequent malignant nodules.Fine needle aspiration cytology (FNAC) is an established technique for the investigation of thyroid lesions.Despite many advantages, FNAC has certain limitations which include specimen adequacy and cytological interpretation, as the sampling is variable and not always representative.Thus a specific diagnosis can only be arrived at after a histological examination [5].

Aim
The aim of the study is to determine the proportion of different patterns (colloid goiter, colloid cyst, papillary carcinoma, etc.) of thyroid lesions among the patients who have undergone surgical treatment.

METHODS
This was a prospective and retrospective study to be conducted on 100 thyroidectomy specimens received in 5-year period (2016-2020) in Department of Pathology in Dr. S.N.Medical College, Jodhpur.Patient's clinical data including clinical details, personal history, and laboratory investigation reports were collected from medical records in surgically resected specimens.The specimen was fixed in 10% formalin and large specimens were cut serially (at 1 cm thickness) before fixing.After fixation, representative areas were selected for paraffin embedding.In case of encapsulated lesions, adequate representation from tumor capsule-thyroid interface was given.Section were cut at 4-5 microns thick and stained with hematoxylin and eosin and studied.Stained histopathology slides were studied in detail.Poor permeation of fixative into thyroid specimen was excluded from the study.

Sample size
It will be an observational study to be conducted on thyroidectomy specimens received in department of pathology, Jodhpur during the period of 5 years.Sample size was calculated at 95% confidence interval and 10% absolute allowable error using the formula for sample size for estimation of a single sample proportion (1 ) Where, Z1-α/2^ = Standard normal deviate for 95% confidence interval (taken as 1.96) P = expected proportion of neoplastic thyroid lesion (taken as 49% as per reference article) E = allowable error (taken as 10%) Sample size was calculated to be 96 thyroid lesions, which was enhanced and round to 100 subjects.

RESULTS
The present study is a retrospective study undertaken for a period of 5 years from 2016 to 2020.A total of 100 specimens of thyroidectomy received during this period were studied and analyzed.Thyroid lesions were seen in patients with age ranging from 10 days to 85 years.Peak incidence of thyroid lesions was seen in the third to sixth decade constituting 77 of cases.The youngest patient in our study group was a 10-day-old male, a case of thyroglossal cyst.The oldest patient was 85-year-old female, with a case of anaplastic carcinoma of thyroid (ATC).Females constituted 90% of the cases studied.The present study showed female: male ratio of 9:1 (Table 1).
Papillary carcinoma was the most common malignant neoplasm, which was seen in 31.82%(7 cases) of malignant neoplasm.The next common malignant neoplastic lesion was follicular carcinoma, which accounted for 9.09% of cases (2 cases) followed by ATC, which was seen in 4.55% (1 case) of cases.The majority of the malignant neoplasms were seen 3 rd to 5 th decade constituting 71.42% of cases studied (Table 3).The youngest patient was 20-year-old female.
Papillary carcinoma was the most common malignant neoplasm in present study accounting for 63.64% (7 cases) of neoplastic lesions.The most common age of presentation was 3 rd -5 th decade (71.43%).The youngest patient was in the second decade (20 years) and oldest patient was a 75 years.All cases were female in the present study.Grossly, largest lesion measurement was 12 cm × 8 cm × 6 cm and smallest lesion measurement was 3 cm × 2 cm × 1 cm.One case showed areas of cystic lesion.

DISCUSSION
A total of 100 consecutive thyroidectomy specimens received in the department of pathology of Dr. S. N. Medical college Jodhpur from 2016 to 2020 were collected and analyzed in this study.Of these, majority (90%) were female.Male accounted for 10%.A study conducted by Padmavathi and Raj [6] reviewed 211 thyroid cases of which 21 cases (9.95%) were male and 190 cases (90.04%) female.

Non-neoplastic lesions
Adenomatous goiter was the most common non-neoplastic lesion in the present study, which accounted for 83.34% (65 cases) of non-neoplastic

Non-neoplastic lesion Number of cases Percentage
Adenomatous

Neoplastic lesions
Neoplastic lesions were 22% of the cases in present study.Among neoplastic lesions, 11 cases (50% of neoplastic lesion) were benign, 1 case (4.54% of neoplastic lesion) was borderline, and 10 cases (45.45% of neoplastic lesion) were malignant.Various studies showed prevalence of neoplastic lesions ranging from 16% to 32%.
Benign neoplastic lesions accounted for 11% (11 cases) of cases studied.In the present study, all benign lesions are follicular adenoma accounted for 100% (11 cases) of benign neoplasms.In a study conducted by Tsegaye and Ergete [7] adenoma constituted for 12.8% of the cases and 60.97% of neoplastic lesions, leading to the 2 nd commonest lesion and most common neoplastic lesion.Padmavathi and Raj [6], all benign neoplasm were follicular adenoma (100% cases).Prabha and Bhuvaneswari [9], 12% benign neoplasm were follicular adenoma (100% cases).
In the present study, one case was categorized as borderline neoplasm Follicular Neoplasm with Uncertain malignant potential (FNUMP) according to 2017 updates of the World Health Organization classification of thyroid tumors, which accounted for 4.54% of neoplastic lesions.Similarly, Koyuncuer et al. [10] have reported borderline neoplasms in 3.33% of the cases (Table 4).
In the present study, malignant neoplasms constituted 10% of the cases studied and 45.45% of neoplastic lesions.Similarly, Ijomone et al. [8] malignancy in 47.61% of neoplastic lesions.Tsegaye and Ergete [7] malignancy in 47.61% of neoplastic lesions.Table 4 shows comparison of neoplastic lesions in the present study with others.

Goyal et al.
Among malignant neoplasms papillary carcinoma was the most common, which accounted for 60% of malignant lesions and 7% cases studied.Similar observation were reported by Bukhari and Sadiq [11] (n=998), where papillary carcinoma accounted for 90% of malignant neoplasms and 13.82% of cases studied.The second most common malignancy was follicular carcinoma, amounting for 2% of cases studied, followed by anaplasic carcinoma constituting 1% of the cases studied which is in concordance with Padmavathi and Raj [6], who have reported 4.08% and 2.04% of follicular carcinoma and anaplastic carcinoma respectively.
Majority of malignant neoplasm were seen from the 3 rd to 5 th decade of life, constituting 71.43% of the cases.Tsegaye and Ergete [7] have reported 65.62% of malignant cases in the same age group.The youngest patient was 20-year-old female who presented with papillary carcinoma.Females were more common to be affected by thyroid malignancy.

Adenomatous goiter
Adenomatous goiter was the most common entity encountered in the present study, which constituted 65% of the cases studied.Various studies by Tsegaye and Ergete [7], Qureshi et al. [12], Bukhari and Sadiq [11], and Albasri et al. [13] have reported 76.9%, 77.88%, 67.93%, and 58.2% of adenomatous goiter, respectively.Age of the patients ranged from 11 to 70 years, however, majority of the cases were seen in the age group of 21-50 years amounting to 69.23% of the cases.Tsegaye and Ergete [7] have reported 79% of the cases in this age group.The lesion was seen predominantly in females as compared to males, where females accounted for 61% (61 cases) of the cases and males constituted 4%.Tsegaye and Ergete [7] also found female preponderance where 82% of the patients were females and 18% were males.

Thyroglossal cyst
The thyroglossal cyst was the second most common entity encountered in the present study, which constituted 9% of the cases studied.Garcia et al. [14] have reported 7% of thyroglossal cyst.Age of patients ranged from 10 days to 45 years, however, majority of the cases were seen in the second decade.

Lymphocytic thyroiditis
Lymphocytic thyroiditis was the third most common entity encountered in the present study 2% of the cases studied.Ahmed et al. [15] the incidence of lymphocytic thyroiditis was 1%.

Hashimoto's thyroiditis
Hashimoto's thyroiditis was the fourth most common lesion encountered in the present study which accounted for 1% of cases studied and the patient was females which was similar to study by Qureshi et al. [12], who reported these lesions in 2.6% of cases with all being females, which was comparable with the present study.

Follicular adenoma
The benign tumors i.e., Follicular Adenomas were present in 11% of all the cases studied.In our study, follicular adenomas were the second most common lesions encountered preceded by adenomatous goiter.
There was an overall female predominance with female to male ratio of 9:2.In the study conducted by Tsegaye and Ergete [7], adenomas were the second most common lesion encountered accounting for 12.8% of cases, preceded only by adenomatous goiter.
Borderline tumors FNUMP: Present study observed 1 case of FNUMP, accounting for 1% of all the cases and 4.55% of neoplastic lesion.In the study conducted by Padmavathi and Raj [6], accounted for 3.2% (2 cases).

Papillary carcinoma
Papillary carcinoma was the most common malignant neoplasm encountered in the present study, which accounted for 31.82%(7 cases) of neoplastic lesions and 70%of malignant neoplasm.The most common age of presentation was 3 rd -5 th decade (71.43%).The youngest patient was in the second decade (20 years).All patients were females (7 cases).
In a study conducted by Qureshi et al. [12], it accounted for 36.6% of the neoplastic lesion and 59.42% of malignant lesions.75.6% of the cases presented in 3 rd -4 th decade with F: M ratio of 5.83:1.In another study by Bukhari and Sadiq [11], it accounted for 54.11% of the neoplastic lesions and 90.2% of malignant neoplasms, which was comparable to the present study.All these studies showed female pre-ponderance.

Follicular carcinoma
Follicular carcinoma was the second most common malignant neoplasm of thyroid in the present study, which was seen in 2 cases, constituting 20% of malignant neoplasms.The age group in the present study ranged from 5 th to 7 th decade and all patients were females.Baloch and LiVolsi [16] have reported an incidence of approximately 5% among all thyroid malignancies in the USA.They have also stated that it is more prevalent (25-40%) in iodine-deficient regions; is more common in women; with wide age distribution, peaking in the fifth and sixth decades, which is in consistent with the present study.In a study conducted by Tsegaye and Ergete [7], it constituted for 15.6% of the malignant tumors (n=64).

Anaplastic carcinoma
Anaplastic carcinoma is highly aggressive thyroid malignancy composed of undifferentiated follicular thyroid cells.ATC is undifferentiated tumors of the thyroid follicular epithelium, accounting for <5% of thyroid tumors and usually presents in elderly patients.In the current study, there was one case (1%) of ATC, was an elderly female of 85 years old.Case was sarcomatoid variant histologically.

Table 1 : Age and sex distribution of thyroid lesions Age groups (in years) Females Males Total
[6]our study, it was observed that over 50% of cases were in age group 11-60 years.Thyroid disease was seen within age range of 9-72 years which is in concordance with Salama et al. 78, (n=845) who reported age range of 9-70 years.The peak incidence of thyroid diseases was seen in the third to sixth decades (21-60 years) constituting 77% of cases which was similar to the studies by Tsegaye and Ergete[7]and Ijomone et al.[8], who have reported 84.2%, 79.16%, 78.94% of the cases respectively in same age group.In the present study, out of 100 cases, 78 (78%) cases were non-neoplastic and 22 (22%) cases were neoplastic.Similarly, in a study conducted by Ijomone et al.[7], non-neoplastic lesions constituted for 66.91%, whereas neoplastic lesion accounted for 31.57% of the cases.In another study by Padmavathi and Raj[6], 70.1% of the lesions were non-neoplastic and 29.9% were neoplastic lesions.