A 77-year-old woman presented to our outpatient clinic with a two-month history of dysphasia. On physical examination, both thyroid lobes were diffusely enlarged with the right lobe being slightly firmer than the left lobe. There were palpable masses along the right cervical levels II and III. Thyroid function test was within normal range. She had no medical history of Hashimoto thyroiditis. Flexible fiberoptic laryngoscopy showed no remarkable finding. We supposed thyroid cancer with lymph node metastasis.

On ultrasonography (iU-22, Philips Medical System, Bothwell, WA, USA) with high frequency linear-array transducer, a larger than 4-cm, irregular shaped, heterogeneously hypoechoic, solid mass occupying the entire right thyroid lobe was seen with suspicious several small internal calcifications. The mass directly invaded the right lateral and posterior wall of trachea and encased right common carotid artery (Fig. 1A, B). We presupposed anaplastic carcinoma, and ultrasoundguided fine needle aspiration (FNA) was carefully performed. The cytologic results revealed suspicious finding for undifferentiated carcinoma. Contrast-enhanced CT of the neck showed a heterogeneously enhancing mass compared to adjacent muscle in the posterior portion of the right thyroid lobe, outgrowing toward the posterior wall of the trachea. There was no grossly defined calcification, hemorrhage, or nonenhancing necrotic portion within the mass. The mass showed indistinct margins with the proximal esophagus (Fig. 1C). Magnetic resonance imaging (MRI) of the neck was done to evaluate esophageal and tracheal invasion. The mass showed heterogeneous enhancement with focal low signal intensity portion, suggesting suspicious necrotic portion. The tumor invaded the proximal esophagus, extended anteriorly to the strap muscle, and encased right common carotid artery (Fig. 1D). These findings suggested ATC with tracheal and vascular invasion with suspicious esophageal invasion. A few enhancing small lymph nodes were seen at the left level II and III with the short diameter of 0.6 cm. Subsequent excisional biopsy of the thyroid lesion was done, and it was histopathologically diagnosed as diffuse large B cell lymphoma.

The patient received three cycles of R-CHOP (rituximab, cyclophosphamide, adriamycin, vincristine, and prednisolone) chemotherapy as well as total 3,816 cGy of intensity-modulated radiation therapy (IMRT), which resulted in complete regression on the CT images after 4 months from the initial diagnosis.

A 73-year-old woman was transferred to our institution with persisting voice change for eight months. Flexible fiberoptic laryngoscopy performed at our institution revealed intraluminal mass emerging from the left posterolateral aspect of the subglottis, cricoid cartilage, and trachea, implying suspicious invasion by left paratracheal mass. Left vocal cord palsy was also noted.

Ultrasonography of neck showed a larger than 4-cm, irregular shaped, heterogeneous hypoechoic mass in the left thyroid gland. The mass extended to the left posterolateral wall of trachea and the left extrathyroid space (Fig. 2A). Thyroid function test was within normal range. There was no medical history of Hashimoto thyroiditis. We supposed ATC, and ultrasound-guided FNA was carried out for the left thyroid mass. The cytology suggested suspicious for malignancy.

CT scan demonstrated an irregular shaped, isodense mass involving the left lobe and isthmus of the thyroid gland, without internal calcification or hemorrhage. Extrathyroid extension was present multi-directionally with adjacent organ invasion; strap muscles anteriorly, tracheal lumen medially, closely abutting the esophagus posteriorly which raised the possibility of esophageal invasion, and left pyriform sinus superiorly. There was no abnormal cervical lymph node (Fig. 2B). MRI of the neck was additionally performed, allowing more distinct demarcation of the lesion boundaries of the known thyroid mass with tracheal, laryngeal, and esophageal invasion. The mass showed heterogeneous enhancement and extend to the lateral and posterior direction. The esophagus had been encroached on by the mass, with loss of the tissue plane between them and this finding allowed diagnosing esophageal invasion. The mass also closely abutted the left internal jugular vein and common carotid artery, but there was no definite vascular invasion. Incisional biopsy was done for the mass, and the lesion was pathologically confirmed as diffuse large B cell lymphoma.

The patient received four cycles of R-CHOP chemotherapy, followed by total 4,000 cGy of IMRT, which resulted in complete regression on the CT images after 4 months from the initial diagnosis.