Rare tracheal mucoepidermoid carcinoma with invasion of thyroid gland initially misdiagnosed as invasive thyroid cancer

Mucoepidermoid carcinoma of the trachea is a rare tumor. We report an 80-year-old male with mucoepidermoid carcinoma in the upper trachea with invasion of the isthmus of thyroid gland. The patient’s major symptom was dyspnea with coughing. Computed tomography scan showed a protruding mass into the trachea suspected of thyroid cancer. Ultrasonography also revealed the suspicion of an invasive thyroid cancer. Under diagnosis of invasive thyroid cancer, total thyroidectomy, tracheal resection and reconstruction were performed. Although preoperative imaging studies indicated that the lesion was primary thyroid cancer, later histopathologic examination revealed that the tumor was rare trachea mucoepidermoid carcinoma. We should consider the possibility that tumors regarded as thyroid cancer with tracheal invasion under imaging studies could be a primary tracheal cancer, especially in patients with obstructive airway symptoms.