|Year : 2013 | Volume
| Issue : 2 | Page : 83-85
Incidental detection of thyroid lung metastasis 20 years after thyroidectomy
Sabeena Shahul Hameed, Anjali Arackal, Kattadiyil Poulose Poulose
Department of Medicine, SUT Hospital, Thiruvananthapuram, India
|Date of Web Publication||16-Apr-2013|
Sabeena Shahul Hameed
Sha Mahal, TC 55/424, Pappanamcode PO, Trivandrum- 18, Kerala
Source of Support: None, Conflict of Interest: None
A 43-year-old woman, with fibroid uterus and menorrhagia with no symptoms attributable to the respiratory system was posted for hysterectomy. Preoperative chest X-ray showed multiple rounded opacities in both lung fields. Thyroidectomy for papillary carcinoma thyroid was performed 20 years back. Further investigations revealed recurrence of thyroid cancer with bilateral lung metastasis.
Keywords: Incidental detection, lung metastasis, papillary carcinoma thyroid
|How to cite this article:|
Hameed SS, Arackal A, Poulose KP. Incidental detection of thyroid lung metastasis 20 years after thyroidectomy. Thyroid Res Pract 2013;10:83-5
|How to cite this URL:|
Hameed SS, Arackal A, Poulose KP. Incidental detection of thyroid lung metastasis 20 years after thyroidectomy. Thyroid Res Pract [serial online] 2013 [cited 2019 Oct 20];10:83-5. Available from: http://www.thetrp.net/text.asp?2013/10/2/83/110596
| Introduction|| |
Clinically detectable thyroid cancer is rare, and accounts for only <1% of all cancers, and 0.5% of all cancer deaths. It is common in the age groups of 40-50 years and is rare in children. The survival depends on the type of thyroid carcinoma best prognosis is for papillary carcinoma thyroid (PCT) when compared to follicular carcinoma (FTC). Lung metastasis is common in PTC, and asymptomatic lung metastasis can occur many years after thyroidectomy, hence warranting periodic evaluation after thyroid surgery. We report here, a case of PCT with asymptomatic lung metastasis 20 years after thyroidectomy, detected on a routine preoperative chest X-ray for preoperative evaluation for hysterectomy.
| Case Report|| |
A 43-year-old lady, came to the Gynecology Department of SUT Hospital, with complaints of menorrhagia. She was evaluated at a local hospital, diagnosed to have fibroid uterus and was referred to our hospital for hysterectomy. She had no history of weight loss/body pain or any respiratory symptoms. She was not a diabetic or hypertensive. Twenty years back she had undergone thyroidectomy with neck dissection for PCT with cervical lymphnode metastasis followed by radioiodine treatment and was on Thyroxine 200 mcg daily.
On examination, she was pale. There were no palpable cervical lymph nodes or thyromegaly. Surgical scar of thyroidectomy was noted in the neck. Preoperative chest radiograph showed multiple rounded opacities in both lung fields [Figure 1] Chest X ray showing multiple rounded opacities in both lung fields]. A provisional diagnosis of recurrence of with lung metastasis was made.
|Figure 1: Chest X ray showing multiple rounded opacities in both lung fields]|
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Her hemoglobin level was 6 g% and further investigations suggested iron deficiency anemia. Renal and liver function tests, lipid profile, and Electrocardiogram were normal. Ultrasound abdomen showed a sub mucosal fibroid. Thyroid function tests were as follows: Thyroid Stimulating Hormone - <0.004 μIU/L (normal range: 0.4-5.0), T3-2.3 nmol /L (1.1- 2.8) and T4-185 nmol/L (65-140). Serum thyroglobulin levels were highly elevated - 300 ng/ml (1.6-60). Further investigations were deferred until hysterectomy. She underwent total abdominal hysterectomy with bilateral salpingo-oopherectomy. CT chest was done on the 4 th post-op day, which showed numerous soft tissue nodules ranging from 5 -18 mm size in both lung fields, suggestive of bilateral pulmonary metastasis [Figure 2] CT Chest showing multiple bilateral nodules suggestive of bilateral pulmonary metastasis]. Whole body radioiodine scan done after withholding thyroxine for 1 month also revealed, minimal residual thyroid bed uptake and bilateral lung uptake. She was given radioiodine therapy followed by thyroxine 150 mcg daily.
|Figure 2: CT Chest showing multiple bilateral nodules suggestive of bilateral pulmonary metastasis|
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| Discussion|| |
Thyroid carcinoma is the most common malignancy of the endocrine system. Differentiated tumors such as PTC and FTC are curable, if detected early. Anaplastic thyroid cancer is aggressive, responds poorly to treatment, and is associated with a bad prognosis. The incidence of thyroid cancer increases with age, and is twice common in women than men, but male sex is associated with a worse prognosis. Other important prognostic factors include large nodule size (>4 cm), evidence for local tumor fixation or invasion into lymph nodes and presence of distant metastasis.
PTC is the most common type of thyroid cancer. In Kerala, it accounts for about 65% of all thyroid malignancies followed by FTC.  It spreads via the lymphatic system and can metastasize hematogenosly to bone and lungs. Because of the relatively slow growth of the tumor, a significant burden of pulmonary metastasis may accumulate with remarkably few symptoms.
Well differentiated thyroid metastasis to the lung are known to occur many years after presentation for thyroid carcinoma. With prolonged follow-up of more than 20 years, metastasis to the cervical lymph nodes can be detected in 35-80% of the patients and distant metastasis including lung in 10-40%  The longest interval reported was thyroid lung metastasis 47 years after thyroid resection  Approximately, 25% of first relapses occurred after 20 years of complete remission. 
A long-term follow-up is required to assess treatment for well differentiated carcinoma because of its prolonged course and very slow growth rate. Serum thyroglobulin measurement should be performed routinely as part of the follow-up. Whole body iodine 131 scintigraphy may demonstrate tumor that is not radiologically detectable. In this patient, T4 elevation and very low TSH may be due to the overdose of thyroxine intake and functioning of thyroid metastasis in view of the markedly elevated thyroglobulin.
The treatment recommended for PTC is radioactive iodine. Motesanib diphosphate, an oral Vascular Endothelial Growth Factor receptor inhibitor has been reported to show partial response in progressive differentiated thyroid cancer.  Samaan and colleagues reported a 5 year survival rate of 61% for patients with lung metastasis and positive radioiodine uptake on the scan and 29% for patients with no uptake.  The doubling time of pulmonary metastasis of differentiated thyroid cancer is among the longest observed, and even growth arrest has occurred without irradiation or chemotherapy. 
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[Figure 1], [Figure 2]