Solitary thyroid gland metastasis from rectal cancer: A case report and review of the literature

Figure 1 Ultrasound characteristics of the left thyroid nodule. A: Sonogram of the thyroid gland showing an irregular hypoechoic nodule (arrow) in the left thyroid; B: The nodule was near the trachea; C: Color Doppler view showing that the nodule had rich blood supply.

Figure 2 Cellular morphology of thyroid tissue aspired by fine needle. A: Photomicrographs show the characteristics of cellular morphology of malignancy (hematoxylin-eosin stain, original magnification × 40); B: Hematoxylin-eosin stain, original magnification × 100; C: Hematoxylin-eosin stain, original magnification × 200; D: Hematoxylin-eosin stain, original magnification × 400.

Figure 3 Microphotographs of the thyroid metastasis. A: Hematoxylin-eosin stain of the thyroid gland detects adenocarcinoma with mucinous features, consistent with metastatic rectal adenocarcinoma (original magnification × 40); B: Original magnification × 100; C: Original magnification × 200; D: Original magnification × 400.

Figure 4 Immunohistochemical images showing metastatic carcinoma in the resected thyroid gland. A-D: Tumor cells are positive for carcinoembryonic antigen (A), cytokeratin 20 (B), EMA (C), and Ki-67 (about 50%) (D); E-I: Tumor cells are negative for HBME1 (E), cytokeratin 7 (F), thyroglobulin (G), synaptophysin (H), and calcitonin (I).

Figure 5 Imaging characteristics of the recurrent left neck mass. A: Ultrasonography of the neck showing a 2.50 cm × 1.64 cm × 1.17 cm mass within left strap muscles and sternocleidomastoid muscle (white arrows; sagittal view); B: Color Doppler view showing the mass has rich blood supply; C: Computed tomography of the neck showing a 2.5 cm × 1.6 cm × 1.1 cm mass within left strap muscles and sternocleidomastoid muscle (white arrow; sagittal view); D: Contrast-enhanced scan showing that the mass was above the internal jugular vein (IJV), with the IJV depressed. IJV: Internal jugular vein; CCA: Common carotid artery.