|Year : 2015 | Volume
| Issue : 4 | Page : 986-988
Papillary thyroid microcarcinoma in Graves' disease presenting as a cystic neck mass
Milind Patil1, Sadishkumar Kamalanathan1, JayaPrakash Sahoo1, Muthupillai Vivekanandan1, Vikram Kate2, Nandini Pandit3, Bhawana Badhe4
1 Department of Endocrinology and Metabolism, Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry, Tamil Nadu, India
2 Department of Surgery, Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry, Tamil Nadu, India
3 Department of Nuclear Medicine, Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry, Tamil Nadu, India
4 Department of Pathology, Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry, Tamil Nadu, India
|Date of Web Publication||15-Feb-2016|
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The presentation of papillary thyroid microcarcinoma (PTMC) as a solitary cystic neck mass is uncommon. Additionally, its association with Graves' disease is very rare. We report a case of occult PTMC, who presented with a cystic neck mass in the background of Graves' disease without any goiter. Imaging like ultrasound of neck, single photon emission computed tomography-CT (SPECT-CT), and technetium scan failed to detect any lesion in the thyroid, which was picked up only by the contrast-enhanced computed tomography (CECT) of neck. The patient underwent total thyroidectomy with right modified lymph node dissection. Our case highlights the presentation of metastatic PTMC as a differential diagnosis of a cystic neck mass even in a patient with Graves' disease without any thyroid enlargement.
Keywords: Metastasis, thyroid carcinoma, thyrotoxicosis
|How to cite this article:|
Patil M, Kamalanathan S, Sahoo J, Vivekanandan M, Kate V, Pandit N, Badhe B. Papillary thyroid microcarcinoma in Graves' disease presenting as a cystic neck mass. J Can Res Ther 2015;11:986-8
|How to cite this URL:|
Patil M, Kamalanathan S, Sahoo J, Vivekanandan M, Kate V, Pandit N, Badhe B. Papillary thyroid microcarcinoma in Graves' disease presenting as a cystic neck mass. J Can Res Ther [serial online] 2015 [cited 2019 Sep 21];11:986-8. Available from: http://www.cancerjournal.net/text.asp?2015/11/4/986/157316
| > Introduction|| |
Papillary thyroid carcinoma (PTC) of a maximum diameter of 10 mm or less is defined as papillary thyroid microcarcinoma (PTMC) according to World Health Organization (WHO) classification and majority of them present as incidentalomas.  The presentation of PTC as a cystic neck mass in a patient with Graves' disease is very rare. There is only one similar case previously reported in the literature.  Here, we report a diagnostically challenging case, where the evaluation of a cystic neck mass led to the ultimate diagnosis of PTMC with apathetic thyrotoxicosis due to Graves' disease.
| > Case report|| |
A 75-year-old nonsmoker male presented with 1-year history of right-sided neck swelling. The patient denied any history of tuberculosis or neck irradiation in the past. There was also no history of thyroid malignancy or autoimmune thyroid disease in the family. Physical examination revealed an 8 cm × 6 cm × 3 cm sized firm, mobile, and nontender swelling with regular margins on the right posterior-lateral aspect of the neck. Fine-needle aspiration biopsy (FNAB) cytology from the swelling was suggestive of cystic metastatic PTC. His baseline thyroid function test (TFT) showed primary thyrotoxicosis: Thyroid-stimulating hormone (TSH) - 0.01 (N: 0.3-5.5 mIU/L), free triiodothyronine (fT 3 ) - 9.75 (N: 3.56-6.51 pmol/L), and free thyroxine (fT 4 ) - 31.40 (N: 11.45-22.65 pmol/L). However, he was clinically euthyroid without any goiter. He was referred to the Endocrinology Department for further evaluation. The technetium scan showed diffuse increased uptake suggestive of Graves' disease without any evidence of focal abnormalities [Figure 1]a]. Both single photon emission computed tomography-CT (SPECT-CT) and ultrasonography (USG) of neck also did not detect any space-occupying lesion in the thyroid. He was started on tablet carbimazole 10 mg thrice daily for thyrotoxicosis. Meanwhile, the contrast-enhanced computed tomography (CECT) of the neck detected a 1 cm × 0.8 cm hypoenhancing lesion in the right lobe of the thyroid [Figure 1]b]. Additionally, it also confirmed the presence of a 5 cm × 5.5 cm cystic mass with 2 cm × 1.7 cm soft tissue component in right posterior triangle of the neck along with multiple cervical lymph nodes [Figure 1]c]. So, total thyroidectomy with right modified lymph node dissection was performed after achieving euthyroid status. The histopathological examination revealed multiple foci of PTMC in the thyroid gland without invasion of its capsule or blood vessels [Figure 1]d]. Six out of 20 lymph nodes removed showed metastatic deposits. The post-surgery iodine scan revealed residual thyroid tissue in the thyroid bed without any distant metastasis for which he has received radioablation. Then, he was discharged on suppressive thyroxine therapy.
|Figure 1: (a) Technetium scan showing diffuse increased uptake without any cold nodule. (b) CECT of neck showing a focal hypo-enhancing lesion (yellow arrow) in the right lobe of the thyroid. (c) CT scan showing a right lateral cystic neck mass having solid (yellow arrow) component. (d) Histopathological section of the thyroid gland showing cystic spaces with papillae lined by tumor cells and central fibro-vascular cores (H and E, ×100)|
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| > Discussion|| |
Cystic neck lymph node as an initial and sole presentation of PTMC is uncommon. , These cystic lesions are produced by subcortical liquefaction of metastatic lymph nodes.  The differential diagnosis of a lateral neck cyst includes branchial cysts, primary lymphoma, and metastasis from thyroid, oronasopharyngeal area, salivary glands, and lungs. As the differentiation between benign and malignant lesion on USG of neck is difficult and FNAB cytology is often inconclusive, these lesions present a diagnostic challenge.  To further complicate the picture, the thyroid may not be enlarged even in the presence of PTMC as in our case. The diagnostic problem in PTMC is not only the fact that the thyroid can be normal in size, but also that, in many cases; it could only be detected postoperatively at final pathology. In such difficult cases, thyroglobulin (Tg) measurement in the washout liquid of the FNAB needle, FNAB immunocytochemistry (ICC), and lymph node excision can be used to rule out thyroid malignancy.  In our patient, FNAB cytology was suggestive of cystic metastatic PTC.
Thyroid cancer occurs concomitantly in Graves' disease with a frequency varying from 0.15 to 15%.  Majority of them are microcarcinoma.  The use of different pathologic sectioning protocols may explain in part the great variability in the prevalence of PTMC in patients with Graves' disease. TSH stimulates growth of normal thyroid tissue through TSH receptor. The differentiated thyroid cancer (DTC) like PTMC also expresses TSH receptors. The binding of TSH to its receptors promotes the growth of cancer cells in euthyroid patients with thyroid carcinoma. So, suppression of TSH might prevent the growth of tumor cells, and this forms the rationale behind TSH suppressive therapy in DTC. However, it is difficult to explain tumor genesis in Graves' disease, where TSH is already suppressed. Rather, thyroid stimulating immunoglobulin (TSI) present in Graves' disease stimulates tumor cell growth acting through TSH receptor.  Also, studies have shown the possible role of inflammatory marker like interleukin-4 in tumor cell survival.  Thus, both autoimmunity and inflammatory mediators may lead to carcinogenesis in Graves' disease. This might be the explanation for the aggressive behavior of the tumor in this patient. However, it is still not clear whether concomitant Graves' disease affects the prognosis of thyroid malignancy. ,
Braga et al.,  described the first case of occult PTMC with Graves' disease who presented as a cystic lateral neck mass. Our case had diagnostic difficulties similar to their case like failure to detect malignant thyroid focus in both USG of neck and nuclear thyroid scans. As both malignancy and underlying autoimmune thyroid disease appear as hypoechoic areas, PTMC can be missed on USG in a patient with Graves' disease. Otherwise, USG can detect very small thyroid lesions even up to 1 mm.  Similarly, the functional nuclear scans like technetium scan and SPECT can miss the cold area due to a small thyroid malignancy (PTMC) in the background of diffusely increased uptake of underlying Graves' disease. However, CECT had picked up this lesion as a hypodense area in the right lobe of the thyroid in our case. While they described a patient with clinically overt hyperthyroidism with goiter, our patient was clinically euthyroid (apathetic thyrotoxicosis) without goiter. Apathetic thyrotoxicosis is common in the elderly patients, who may not have classical features of thyrotoxicosis.
To conclude, this case emphasizes the possible consideration of thyroid cancer while evaluating a cystic neck mass even in the presence of Graves' disease. Additionally, clinical examination and relevant imaging modalities like USG of neck, technetium scan, and SPECT may miss the underlying thyroid lesion.
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