|Year : 2017 | Volume
| Issue : 3 | Page : 112-117
A histopathological study of autopsied thyroid
Murari Mohan Das1, Bhawna Bhutoria Jain1, Biswajit Sukul2, Sarbani Chattopadhyay3
1 Department of Pathology, Medical College and Hospital, Kolkata, India
2 Department of Forensic Medicine, Medical College and Hospital, Kolkata, India
3 Department of Pathology, North Bengal Medical College, Darjeeling, West Bengal, India
|Date of Web Publication||9-Oct-2017|
Bhawna Bhutoria Jain
862 Block-P, New Alipore, Kolkata - 700 053, West Bengal
Source of Support: None, Conflict of Interest: None
Introduction: To find the prevalence and frequency of different thyroid lesions, especially papillary carcinoma in our population, we conducted a histopathological study of thyroid glands obtained from medicolegal autopsy in cases with no obvious history of thyroid disease in our region.
Methods: The study population comprised deceased undergoing medicolegal autopsy in police morgue under the Forensic Medicine Department of our institution over a period of 18 months. Thyroid gland was dissected out at the time of autopsy. Gross and histopathological findings of each specimen were documented in details. The data were collected, compiled, and tabulated, and statistical analysis was done using IBM SPSS version 20 software and Microsoft Office Excel 2007.
Results: The total number of samples was 240. The mean age of the study participants was 42.35 years. About 60.4% were male, and 39.6% were female. Mean weight of thyroid was 34.08 g. In 56 cases (23.3%), single or multiple nodules were observed on cut section of thyroid. Minimum and maximum size of the nodules was 0.40 and 1.30 cm, respectively, with mean size of 0.74 cm in diameter. On microscopic examination, 54.6% of the cases were seen to be normal in histological examination while 45.4% had one or other histopathological changes. Among the nonneoplastic lesions, the most common lesions seen were nodular colloid goiter (20%) and lymphocytic thyroiditis (7.5%). Papillary thyroid carcinoma was seen in 5 (2.1%) cases. Among the five cases of papillary carcinoma, three cases had papillary microcarcinoma (<1 cm). All cases of papillary carcinoma showed strong diffuse reactivity with cytokeratin-19 immunostain.
Keywords: Autopsy, cytokeratin-19, papillary carcinoma, thyroid
|How to cite this article:|
Das MM, Jain BB, Sukul B, Chattopadhyay S. A histopathological study of autopsied thyroid. Thyroid Res Pract 2017;14:112-7
| Introduction|| |
Thyroid disorders form colossal burden to our society. Although chronic thyroid diseases have become a major global morbidity and mortality, there is scarcity of literature regarding the burden of chronic thyroid diseases in Eastern India. To study asymptomatic thyroid lesions in living individuals is a difficult task, and autopsy study is the best possible way to work on it. The data obtained can be utilized for further epidemiological and clinical studies. This study gives us information about the prevalence and frequency of different thyroid lesions, especially papillary carcinoma in people residing in our region.
| Methods|| |
This study was initiated after receiving approval of the Ethical Committee of our institution.
Objectives of this study were to determine (1) variation in size and weight of thyroid gland according to age and sex. (2) To categorize the different morphological changes. (3) To find the prevalence of different thyroid pathologies and their distribution with respect to age and sex and (4) To evaluate the immunohistochemical expression of neoplastic lesions if any and compare with nonneoplastic thyroid.
It is a cross-sectional descriptive study with convenient sampling done over the period of 18 months. The study population comprised deceased undergoing autopsy in police morgue under the Forensic Medicine Department of our institution.
Inform consent for autopsy and relevant history with special reference to thyroid disorder was obtained from the relatives of deceased and inquest papers. The samples were retrieved after meticulous autopsy.
Specimen was discarded if obtained from decomposed or mutilated body or when there was injury over the neck involving thyroid gland as well as from the subject in whom there was previous history of thyroid disorder. After retrieval, the specimen was fixed in 10% neutral-buffered formalin. Grossing of the collected specimens was done in the pathology department. The gross descriptions such as size, weight, surface, dimension, and cut surface of thyroid gland were noted. Photographs of the specimens were taken. Multiple sections were taken from different areas of the mentioned organ (minimum three sections each from both lobes and isthmus), and they were processed and stained with hematoxylin and eosin stain. The prepared slides were examined, and the findings were noted.
Immunohistochemical study was done in selected cases.
Data were collected and compiled and properly tabulated in master chart. Representative tables and graphs were made and subjected to suitable statistical analysis using appropriate methods. Statistical analysis was done using IBM SPSS version 20 bit 32 software and Microsoft Office Excel 2007.
| Results|| |
In the present study, thyroid gland obtained from 240 cases was finally studied. Males constituted 60.4% (n = 145) and females 39.6% (n = 95). The median age of the study participants was 40 years (minimum - 9 years and maximum - 88 years).
Mean weight of thyroid gland was found to be 34.08 g (minimum - 15 g and maximum - 82 g) with standard deviation (SD) - 12.477 and median weight 32 g.
In 56 cases, nodularity was seen on cut section. There were multiple nodules in 4.2% cases. Single nodule was present in the left lobe in 10% and in the right lobe 9.2% of thyroid glands. Distribution according to the presence of nodularity on cut section of thyroid is presented in [Table 1].
Minimum and maximum size of the nodules was 0.40 and 1.30 cm, respectively, with mean size of 0.74 cm in diameter. The nodules were solid, cystic, hemorrhagic, and variegated in 17.1%, 4.6%, 1.3%, and 0.4%, respectively.
[Table 2] represents the frequency distribution of characteristic microscopic findings while the age group distribution of each category of microscopic finding is depicted in [Table 3]. The majority of thyroid glands (n = 131) revealed normal histological features [Figure 1]a. Diagnostic histopathological changes were seen in 109 (45.4%) cases. The most common finding was nodular colloid morphology [Figure 1]b seen in 48 cases, of which 16 were male and 32 female. Totally, 22 (9.1%) cases showed histopathological features of autoimmune thyroiditis which includes lymphocytic thyroiditis [Figure 1]c and hashimoto thyroiditis in 18 (7.4%) and 4 (1.7%) of cases, respectively. According to age group, these were common in 31–40 years of age.
|Figure 1: Photomicrograph showing following features. (a) Normal thyroid gland revealing round to oval follicles lined by a single layer of follicular cells and filled with pale eosinophilic colloid (H and E, ×100). (b) Collections of small follicles protruding into the lumen of larger follicles referred to as Sanderson polsters are suggestive of hyperplastic change (H and E, ×400). (c) Lymphocytic thyroiditis (H and E, ×100). (d) Nodular aggregates of C-cells (H and E, ×200)|
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|Table 3: Age group distribution of different neoplastic and nonneoplastic thyroid pathology|
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Five cases of latent papillary carcinoma were revealed based on characteristic nuclear features and all of these cases were within 20–60 years of age. The occurrence rate of latent papillary carcinoma in female and male was 4.39% and 0.69%, respectively. Among the five cases of papillary carcinoma, three cases were papillary microcarcinoma where tumor size ≤1 cm [Figure 2]a. None was encapsulated.
|Figure 2: Photomicrographs showing following features. (a) Papillary microcarcinoma (<1 cm) surrounded by normal thyroid follicles (H and E, ×40). (b) Papillary microcarcinoma stained strongly positive with cytokeratin-19 (×40). (c) Histology of intrathyroid parathyroid (H and E, ×40). (d) Parathyroid stained with chromogranin A (×40)|
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On immunohistochemical examination, cytokeratin-19 (CK-19) expression was strongly positive in all five cases of papillary thyroid carcinoma (PTC) (100%). All showed diffuse positivity in the area where papillary microcarcinoma was present [Figure 2]b, and the surrounding normal area did not show reactivity to CK-19 stain which was found to be significant by Fisher's exact test (P = 0.000 which is <0.01). Histologically, suspicious areas of C-cell hyperplasia were found in seven cases; out of these seven (83.3%) cases, six were male, which was found to be significant by Fisher's exact test (P = 0.030 which is <0.05) [Figure 1]d.
Also noted was the presence of intrathyroid parathyroid gland in 13.33% of the total cases. All of these parathyroid glands were stained with chromogranin A immunostain, which was not taken by surrounding normal thyroid tissue [Figure 2]c and [Figure 2]d.
| Discussion|| |
Pathological thyroid findings are said to be common in autopsy populations; however, their nature and true prevalence in this region is not well documented. Autopsy provides unique insight into the prevalence of asymptomatic thyroid diseases in the community. Therefore, we undertook this study to find the prevalence and frequency of different thyroid lesions in the people of this region. We characterized the morphology of thyroid gland on postmortem thyroid specimens taken from deceased who died with some cause not related to any type of known thyroid disorder.
Variation in weight
In this study, mean weight of thyroid gland was 34.08 g (minimum - 15 g and maximum - 82 g) with SD - 12.477. Average thyroid weight noted in males was 30.57 g while in females, it was 39.43 g. There is a wide variation in weight measurements in different studies. Williams et al. recorded it to be 25 g in males and a little more in females. In Japanese adults between the ages of 20 and 50 years, the mean weight in adults was about 15 g in males and 13 g in females. In India, a study done by Harjeet et al. in 2004 on shape and weight of thyroid gland on 410 males and 160 females during medicolegal autopsies found that the mean weight of the gland was 15.01 ± 7.69 g in males and 13.16 ± 5.64 g in females with statistically insignificant sexual and age-wise differences. In a recent Turkish study, mean thyroid weight was 26.11 ± 8.14 g. In males, it was 26.93 ± 7.96 g while in females, it was 21.93 ± 7.98 g.
The majority of thyroid glands appeared normal in morphology.
On cut section of thyroid glands, nodularity was seen in 56 cases (23.3%). There were multiple nodules in 4.2% cases. The single nodule was present in the left lobe and right lobe in 10% and 9.2% of thyroid glands, respectively.
Lang et al. examined thyroid glands during a 2-year period in a sequence of 1020 autopsies and found approximately 22% were goitrous.
Tamhane and Gharib state that thyroid nodules are common; their prevalence in the general population is high; the percentages vary depending on the identification method: 2%–6% (palpation), 19%–35% (ultrasound), and 8%–65% (autopsy data).
According to Popoveniuc and Jonklaas, the estimated prevalence by palpation alone ranges from 4% to 7% whereas the current use of high-resolution ultrasonography (US) detects nodules in 20%–76% of the adult population. The reported frequencies detected by the US correlate with the prevalence reported at surgery and autopsy with ranges between 50% and 65%. In the Indian population, according to a 2009 study, the prevalence of a palpable thyroid nodule in the community is about 12.2% in Southern India.
Characteristic histopathological changes in our study were seen in 109 (45.4%) cases while the rest showed normal histology. Out of these 109 autopsy specimens, 102 (93.6%) were seen to have a nonneoplastic diagnosis while 7 (6.4%) cases were diagnosed to have neoplastic pathology. Avetisian and Petrova in a study on 162 subjects found the frequency of abnormal thyroid glands to be 40.7%. However, Furmanchuk and Rusak (1992) reported 145 (67.5%) abnormal out of 215 glands.
The most common histological pattern seen in our study was nodular hyperplasia in 48/240 (20%) cases. Six cases met the criteria of follicular adenoma diagnosis. The adenoma is usually single, encapsulated lesion, dissimilar from the remaining parenchyma, compresses the adjacent tissue and is composed mainly of follicles that are smaller than those of the normal gland. The lesion of nodular hyperplasia is almost always one of many nodules, its encapsulation is incomplete, the follicular size is variable, some or all of the follicles are larger than those in the surrounding gland, and there is no compression of the adjacent parenchyma.
The frequency of microscopic manifestations of nodular hyperplasia of thyroid at autopsy varies greatly depending on the geographic location of the population being investigated.
In a series of 420 autopsies in 1999, Fleischmann and Hardmeier found that the most common (39%) thyroid pathology was hyperplastic nodules, similar to Avetisian and Petrova, of which 49.4% were male, and 33.4% were female. Nearly 2.4% of all patients had adenomas, 1.9% primary carcinomas, and 2.8% thyroid metastases. Inflammatory infiltrates were observed in 6.6% of cases (9.4% of females and 4.4 of males).
Features suggestive of autoimmune thyroiditis in our study were noted in 22 cases, that is, 7.5% of males and 11.5% of females. Autoimmune thyroiditis includes Hashimoto thyroiditis, lymphocytic thyroiditis, and Graves's disease. Histological features suggestive of lymphocytic thyroiditis in our study were noted in 18 (7.5%) cases and Hashimoto thyroiditis in 4 (1.66%) cases. None showed features of Graves' disease. In a series of 420 autopsies, Fleischmann and Hardmeier found inflammatory infiltrates in 6.6% of cases (9.4% of females and 4.4% of males). Scopa et al. studied thyroid glands obtained from 120 autopsies and found thyroiditis in 9% cases  while Furmanchuk and Rusak in 1992 found thyroiditis in 6.5% cases among 122 total cases in their study on autopsied thyroid. Although there is scarcity of autopsy study regarding autoimmune thyroiditis in India, in a cross-sectional, multicentric, epidemiological study which was conducted in eight major cities (Bengaluru, Chennai, New Delhi, Goa, Mumbai, Hyderabad, Ahmedabad, and Kolkata) of India to study the prevalence of hypothyroidism among adult population, antithyroid peroxidase antibodies suggesting autoimmunity were detected in 21.85% (n = 1171) patients.
Focal lymphocytic infiltration was noted in twenty cases in our study. These did not confirm to the morphological diagnosis of autoimmune thyroiditis. As per “Rosai and Ackerman's surgical pathology”, the common denominator of autoimmune thyroiditis in particular is the presence of extensive lymphocytic infiltration of the gland associated with germinal center formation. It is the appearance of the intervening follicles that determines the category to which a given case belongs: Grave's disease when the follicles are diffusely hyperplastic, lymphocytic thyroiditis when they are relatively normal, and Hashimoto thyroiditis when they are lined by follicular cells showing extensive oncocytic change. Focal nonspecific collections of lymphocytes are seen at autopsy in the thyroid of about one-half of females and one-fourth of males; this finding is regarded as a subclinical manifestation of focal lymphocytic thyroiditis.
Kurashima and Hirokawa in 1985 did an autopsy study on 169 cases on the thyroid glands obtained from patients, ranging in age from 63 to 97 years. Focal lymphocytic infiltration was found in 29 (17.2%) of 169 thyroid glands.
Prevalence of thyroid carcinoma
Totally, six cases of thyroid carcinoma were encountered in our study. One was medullary carcinoma, and other five included papillary carcinoma including three cases of papillary microcarcinoma. According to the World Health Organization, “papillary microcarcinoma” is defined as a tumor smaller than 1 cm which is incidentally discovered and usually has an excellent prognosis. It may be appropriate to apply the terminology of occult papillary carcinoma where malignancy is found in the thyroid subsequent to discovery of metastatic tumor and latent papillary carcinoma where cancer is discovered incidentally in a thyroidectomy/lobectomy specimen or at autopsy. Occult and latent papillary carcinoma may or may not be microcarcinoma. There is enormous difference in the prevalence of thyroid carcinoma (or microcarcinoma) in autopsy. The range is from 0.01% in the US to 35.6% in Finland. This might be explained by genetic factors and environmental factors. In epidemiological studies from worldwide variety of sources, reported frequency of latent papillary carcinoma ranges from 3.6% to 22% by Wang and Crapo and Martinez-Tello et al. in Spain, respectively.
The prevalence of papillary carcinoma in our study is 2.1% (5 out of 240 cases), of which one was male and four females. The age of male was 58 years while the females were of 55 years, 30 years, 25 and 60 years of age. In a study on the incidence of occult papillary carcinoma of thyroid in the Indian population, thyroid cancer was seen in 7/358 patients with the incidence of 2%.
The Indian Council of Medical Research established the National Cancer Registry Program (NCRP), and the NCRP collected the data of more than 300,000 cancer patients between the periods 1984 and 1993. The nationwide relative frequency of thyroid cancer among all the cancer cases was 0.1%–0.2%.
However, no recent autopsy study depicting the prevalence of thyroid cancer in the Indian population was noted on literature search.
All five cases of papillary carcinoma showed diffuse and strong CK-19 immunoreactivity. Miettinen et al. in their study of Keratin subsets on paraffin-embedded papillary and follicular thyroid confirmed that CK-19 is a useful marker for differentiating between papillary carcinoma and papillary hyperplasia. There are different studies which showed a very high sensitivity and specificity of CK-19 in PTC. Baloch et al. showed CK-19 stains strongly and diffusely all cases of all 10 usual type PTC. All 26 follicular variant PTC cases showed strong staining of the areas with papillary cancer nuclei and moderate to strong staining in areas of the tumor without obvious nuclear features of papillary cancer. As the control group, they took cases consisting of follicular adenoma, follicular carcinoma, and hyperplastic nodule showed no staining with CK-19.
| Conclusion|| |
Through the present study, we provide the data regarding the distribution of different types of thyroid pathologies in our region. We also assessed the expression and pattern of the distribution of CK-19 in PTC and reinforce its potential as a useful marker for PTC.
There may be an asymptomatic case of papillary carcinoma that is highlighted in this study. The prevalence of 9.1% of autoimmune thyroiditis and 2.1% of papillary carcinoma of thyroid speaks about the burden of this disease in the population which could have been detected by thorough thyroid screening tests. Limitations of the present study which may influence the results if applied to the general population include small sample size and overrepresentation of males. Although females constituted only 40% of the study population, greater percentage of females showed the various diagnostic pathological lesions such as nodular hyperplasia, thyroiditis, and papillary carcinoma.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]