Prevalence of incidental thyroid carcinoma (ITC) among total thyroidectomies performed by PSU-UOR on multinodular goiters; how accurate is the diagnosis and how rational is the treatment?

Methods Indications for total thyroidectomy at PSU-THK include Thy 3-5 on FNAC, retrosternal goiters, those presenting with symptoms suggestive of obstruction or infiltration and cosmesis. However thy1-2 are also offered depending on the situation. Patients who had undergone total thyroidectomy for MNG with FNAC reporting Thy1-2, as well as those with Thy-3 FNAC, from 1st April 2014 to 31st march 2016 were analyzed.


Introduction:
Thyroid lesions are common and are observed in 4-7% of the population, being more common among women (1,2). Standard assessment of multinodular goiter in many centres involve Thyroid function tests, Ultrasound scan and fine needle aspiration cytology. The foremost objective is detection of thyroid cancer, the most common endocrine tumour accounting for 90% of them (3,4). FNAC is regarded as the single most accurate, safe, effective and economical technique in identifying thyroid cancer (1,5). Considering the prevalence of thyroid disease and thyroid malignancy in the population it is important to assess the accuracy of diagnostic methods, particularly FNAC, employed by local health care systems to detect thyroid cancer, as the correct decision making following surgery is lifesaving. The aim of our study was to detect the accuracy of preoperative diagnosis using FNAC in detecting thyroid cancer among patients undergoing total thyroidectomy at Professorial Surgical Unit, University of Ruhuna (PSU-UOR), Teaching Hospital, Karapitiya.
In PSU-UOR, over 200 total thyroidectomies are performed per year (6) and a comprehensive database has been maintained regarding thyroid patients who have undergone surgery for the last five years. The data from patients who had undergone total thyroidectomy for multinodular goiter with Thy 1, 2 and 3 FNAC from 1 st April 2014 to 31 st march 2016 were selected for this analysis. Thy 4 and thy 5 are offered total thyroidectomy by almost all the centers including PSU-UOR and were therefore excluded due to unambiguity regarding their management (4). Ultrasonically confirmed solitary nodules were also excluded as their management is discussed separately. All the patients selected had one or more of the mentioned indications and all of them had opted for total thyroidectomy. A Performa was prepared and utilized to extract information from PSU-DOS database about patients who had total thyroidectomy during the said time period.
Using completed Performa patients' demography, FNAC and final histology reports from the department of Pathology, University of Ruhuna were included in the analysis.

HCA-Hurthle Cell Adenoma,FA-Follicular Adenoma
In the Thy 1 and 2 group final Histology revealed malignancy in 14 patients ( Table 2). All of them were females. Nine of them had papillary while 4 had follicular carcinoma. The other patient had a lymphoma. Among the 58 patients of Thy 3 group, 15 (25.85%) had confirmed malignancy. Thirteen of them were females. Ten were papillary, 4 were follicular and 1 was medullary. Thyroid enlargement, especially MNG, is a pathology that frequently presents to surgical clinics all over the world. There is an added possibility of missing the diagnosis of ITC among MNG by clinical examination. Ultrasound and FNAC make the clinicians wearily entertaining the possibility of thyroid cancer in all the patients who present to them with thyroid enlargement. In considering the clinical risk of carcinoma in MNG, history of radiation, calcification on Ultrasound or neck x-rays, as well as the family history of thyroid disease are important (7). Bombil et al 2014 identified the risk of missing a cancer with FNAC as at 5.7% in a series of 166 thyroidectomies performed for MNG with benign FNAC (8). Most of them were papillary carcinomas. Alecu et al 2014 concluded that benign thyroid pathology, particularly colloid goiter and Hashimoto's, are best managed by total thyroidectomy after their 145 patient series showed 6.9% risk of FNACs missing a cancer of thyroid (9). Approaching the issue from a  (12). Above facts justifies offering TT for all cases of thy 3.
However, TT is not a surgery which can be taken lightly even in a high volume thyroid center with potential complications and possible co-morbidities. Further research need to be directed to search for means of identifying ITC in MNGs with Thy 1-3 cytology accurately which will allow clinicians to offer this major surgery for those who need it on solid clinical grounds.