a 64-year - old female was diagnosed with thyroid cancer in 2004 and was treated by thyroidectomy . during follow - up , blood free t4 levels were increased and an i-131 whole body scan was performed .
1 ) . additional chest computed tomography ( ct ) showed a 1.2-cm - long nodule at the left lower lobe , which matched the location in the i-131 scan results ( fig .
2 ) . a thoracoscopic approach was first attempted , but failed due to adhesion of left upper lobe .
thus , a thoracotomy was performed . a 1-cm - long nodule surrounded by pulmonary tissue
was observed next to the inferior pulmonary vein . a blood vessel branching off from the pulmonary vein and going through the nodule was also observed .
the blood vessel was ligated , excised , and isolated from the inferior pulmonary vein .
endogia ( covidien , mansfield , usa ) was then used for wedge resection of the nodule ( fig .
it was identified as ectopic thyroid tissue , but it was not observed to be malignant ( fig . 5 ) .
the patient 's chest tube was removed on day 5 after surgery , and the patient was discharged on day 10 without other complications .
the thyroid migrates from endodermal protrusion of the first and second pharyngeal arch at 3 weeks to 7 weeks of gestation .
a thyroglossal duct forms along the descending path of the thyroid and undergoes atrophy during the embryonic stage . during this development ,
abnormal migration of the thyroid causes it to be misplaced , which is known as ectopic thyroid .
the prevalence of ectopic thyroid is 1 in every 100,000 to 300,000 in the general population and 1 in 4,000 to 8,000 in patients with thyroid disease .
ectopic thyroid is mostly symptomless , but can have various symptoms based on the size and location .
in particular , when located inside or around the trachea , the patient may experience aphagia , hoarseness , dyspnea , or a foreign body sensation as the size increases .
however , most cases of ectopic intrapulmonary thyroid are symptomless , as in this case study .
it is observed through radiation screening and ct scans and is reported to cause dry cough , dyspnea , hemoptysis aphagia , and superior vena cava syndrome .
in addition , it is reported that orthotropic thyroid coexists in all cases of intrapulmonary thyroid .
radiologic examinations for diagnosis include ct , magnetic resonance imaging , tc-99 m , i-131 , and i-123 .
blind bronchoscope aspiration and real - time ultrasound aspiration have been used to obtain samples for histological diagnosis .
a differential diagnosis of ectopic intrapulmonary thyroid includes thyroid cancer metastasis , thymoma , neuroma , and germ cell tumor . among ectopic thyroid cases ,
prior to ectopic intrapulmonary thyroid treatment , the patient 's age , presence of orthotropic thyroid , symptoms due to nodules and their severity , thyroid hormone level , and malignancy potential need to be considered to perform surgical or medical treatment . depending on the position of the tissue , sternotomy or thoracotomy can be performed for surgical treatment . also , thoracoscopic treatment can also be considered . in conclusion
, ectopic thyroid occurs due to early developmental differentiation problems and can be positioned in different locations based on thyroid development .
it is usually symptomless , but can cause symptoms depending on its location , size , and malignance .
this case reports a patient with a history of thyroid cancer and abnormal thyroid function .
surgery was performed in order to determine malignancy , and to diagnose and treat the ectopic thyroid .
 an ectopic thyroid is caused by abnormalities in migration of the thyroid during development and rarely occurs in the thoracic cavity or the abdominal cavity . 
 we report the case of a 64-year - old female who had abnormal findings from a thyroid hormone test during follow - up after thyroid cancer surgery . based on the radioisotope diagnostic test , 
 an ectopic thyroid inside the thoracic cavity was suspected . through surgical treatment , 
 the patient was diagnosed with ectopic intrapulmonary thyroid . 
 ectopic intrapulmonary thyroid is reported to be very rare and the case is described along with a literature review . 
CASE REPORT
DISCUSSION