A 63-year-old female with an anterior neck mass and mild hoarseness sought treatment at our clinic. The patient's condition was stable until mild hoarseness developed for no apparent reason 6 months prior to presentation at our clinic. However, the patient was not concerned by this symptom. Subsequently, the patient found a painless mass on her anterior neck. There were no other clinical symptoms, such as dyspnoea, neck pain, nervousness or rapid heartbeat. Six years prior, the patient underwent a proximal subtotal gastrectomy and lymph node dissection for Siewert III oesophagogastric junction cancer. The histologic type was moderately differentiated adenocarcinoma with ulceration. The cancer had grown into the serosa of the stomach (T3). Cancer cells were found in 8 nearby lymph nodes (N3), but no distant metastasis was observed. Therefore, the patient's disease was classified as T3N3M0, stage IIIb. Eight cycles of chemotherapy (5-FU and cisplatin) every 3 weeks were administered after surgery. The patient's condition remained stable each year during the follow-up period. No other personal or family history of disease was reported. Physical examination at admission revealed a solitary painless thyroid nodule, 2 cm by 3 cm, in the right lobe of the thyroid gland that moved up and down with swallowing. Tests revealed that the full blood count, liver function, renal function, thyroid function, and level of serum tumor markers, such as carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA19-9), carbohydrate antigen 125 (CA125) and alpha-fetoprotein (AFP) were within normal ranges.
Ultrasonography revealed a non-homogenous hypoechoic solid mass, 49 mm x 34 cm in size, with blurred boundaries and a rich blood flow signal, in the right lobe of the thyroid gland (Figure 1A). Several enlarged lymph nodes were found in the right neck (Figure 1B). Computed tomography (CT) revealed that the tumor occupied almost the entire right lobe of the thyroid gland, with heterogeneous enhancement on the arterial phase (Figure 2). Direct laryngoscopy showed that the appearance and movement of the left vocal cord appeared normal, while the right vocal cord had some dyskinesia. Given these results, a malignant tumor of the thyroid was suspected. Fine needle aspiration was suggested, but the patient refused this procedure and insisted on thyroid surgery.
The patient underwent a right thyroidectomy, and the tumor was found to have invaded the right recurrent laryngeal nerve and trachea. Intraoperative frozen section analysis showed that the thyroid follicles had been diffusely infiltrated by poorly differentiated tumor cells with morphology resembling gastrointestinal lesions. The blood vessels and lymphatic vessels were filled with tumor cells. The following immunohistochemistry staining results were obtained (Figure 3): AE1/AE3 (+), CEA (+), CDX-2 (+), cytokeratin 7 (-), Ki-67 90% (+), calcitonin (-), thyroid transcription factor-1 (-), thyroglobulin (-), synaptophysin (-), chromogranin A (-), and neuron-specific enolase (-). The characteristics of these tumors more closely resembled those of metastatic gastric adenocarcinoma than primary thyroid malignancies. Based on the patient's history of gastric cancer, the histopathological evaluation and immunohistochemistry staining results, the patient was diagnosed with gastric cancer metastasis to the thyroid.
There were no complications with the surgery. However, the patient refused further treatment and died from general deterioration within 6 months.