Thyroid Follicular Adenoma with Tracheal Stenosis

Some cases of thyroid malignant tumors and thyroid lymphoma were reported to have caused tracheal stenosis and choking. Benign thyroid tumors with dyspnea due to tracheal stenosis are very rare. We experienced a benign thyroid tumor that caused tracheal stenosis and dyspnea. In the preoperative CT, there was tracheal stenosis due to enlarged bilateral thyroid lobes and the width of the stenotic lumen was 7mm. Subtotal thyroidectomy improved the dyspnea. Postoperative histopathologic examination confirmed follicular adenoma without malignant lesions or chronic thyroiditis. On postoperative CT, the tracheal stenosis had improved and the lumen had increased to 15mm. The above findings would suggest that it should be keep in mind that even benign thyroid tumors with tracheal stenosis of less than 7mm in the lumen have the possibility of causing dyspnea. Pathological diagnosis.


Surgical findings
After the septic shock and pneumonia improved, he underwent subtotal thyroidectomy with preservation of the bilateral upper thyroid poles. The postoperative progress was good, and there was no hemorrhage or vocal cord paralysis, clinical finding of tracheomalacia

Introduction
Thyroid diseases with airway stenosis caused by cancer and lymphoma have been reported [1,2]. We previously presented that a case of a huge malignant lymphoma with chronic thyroiditis that cause dyspnea due to tracheal stenosis [3]. Benign thyroid tumors with dyspnea due to tracheal stenosis are exceedingly rare [4]. However, we recently experienced a benign thyroid tumor with dyspnea due to tracheal stenosis and performed subtotal thyroidectomy. This report describes the clinical findings, imaging examination, operation and postoperative progress and some considerations by referring to various studies.

Case Report
Patient 75 year's old, male, Japanese

Past history
Ten years ago, he suffered a traumatic injury to his upper right limb that required amputation, during which a tracheotomy was performed to secure the airway under general anesthesia. This tracheostomy was closed after the operation.
One month ago, surgery for a ruptured Achilles tendon was performed under general anesthesia by oral intubation in another hospital, and the postoperative progress was good. or, especially, postoperative complications. In the postoperative CT, tracheal stenosis had improved and widened to 15mm from 7mm in the lumen. Therefore, the tracheostoma was closed and there was no respiratory distress.

Discussion
Alfonso A, et al. [5] reported that 67 % of benign thyroid tumors with stenosis of the trachea coexisted with chronic thyroiditis. In our case, pathological examination was diagnosed as follicular adenoma and showed no chronic thyroiditis lesions. In the anti-thyroid autoantibodies, the microsome test and the thyroglobulin test were within the normal range. Yamada T, et al. [6] presented a case of adenomatous goiter with a fatal outcome caused by airway stenosis. Therefore, even benign thyroid tumors with advanced tracheal stenosis should be treated aggressively with surgery. Agarwal A, et al. [7] revealed that the incidence of tracheomalacia with large stroma was high even in benign thyroid tumors. Concerning the management of tracheomalacia, some hospitals performed tracheostomy and then inserted a T-tube into the trachea lumen after subtotal thyroidectomy [8,9]. In our case, we performed tracheotomy before subtotal thyroidectomy and observed no clinical findings of tracheomalacia postoperatively. Postoperative CT confirmed that the tracheal stenosis had improved and the lumen had spread to 15mm from 7mm ( Figure  3). Therefore, the tracheostoma could be closed without respiratory distress. Yoshida Y, et al. [10] described that a tracheal lumen diameter   over 8mm in adults would cause no ventilation failure. In the present case, the patient underwent tracheotomy before amputation of his arm, which might have caused a morphological abnormality of the trachea after the surgery. Moreover, the intratracheal stimulation by oral intubation at the time of Achilles tendon surgery before visiting our hospital, in addition to the tracheal stenosis from the goiter, constricted the tracheal lumen to 7mm causing breathing difficulty.

Conclusion
We present a case of a 75-year-old Japanese male patient with dyspnea due to a benign thyroid tumor. In the preoperative CT, a tracheal stenosis due to enlarged bilateral thyroid lobes had decreased the width of the lumen to 7mm. Subtotal thyroidectomy improved dyspnea. Postoperative histopathologic examination confirmed follicular adenoma without malignancy or chronic thyroiditis. On postoperative CT, the tracheal stenosis had improved and the width of the lumen had increased to 15mm from 7mm. Our case suggests that a benign thyroid tumor with tracheal stenosis of the lumen has the possibility of causing dyspnea or death. Therefore, even benign thyroid tumors with advanced tracheal stenosis should be treated aggressively with surgery.