PMC9445312_01
Ultrasonographic images of the thyroid and lateral lymph nodes. (A) The thyroid tissue displayed a heterogeneous echoic appearance on gray-scale sonography. (B,C) Cervical lymph nodes showed round shape and absence of hilum on gray-scale sonography. (D-F) CDFI showed different vascular distribution of cervical lymph nodes. (D) A mixed-echoic cervical lymph node with more than 90% of cystic change revealed no blood flow signal inside this lymph node. (E) A heterogeneous echoic cervical lymph node showed rich blood flow signal inside and around this lymph node. (F) A heterogeneous echoic cervical lymph node showed rich blood flow signal around this lymph node.
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F1
The neck ultrasound revealed diffuse and swollen heterogeneous hypo-echoic thyroid tissue (Figure 1A). Cervical lymph nodes were enlarged, round and had no hilum on grayscale sonography, with different vascular distributions on color Doppler flow imaging (CDFI) mode (Figures 1B-F).
CT and MR images of the neck. (A) Transverse and (B) coronal sections of the neck revealed swelled thyroid with multiple enlarged cervical lymph nodes on CT. (C) Transverse and (D) coronal sections of the neck revealed swelled thyroid with multiple enlarged cervical lymph nodes on MR, causing the tracheal compression and narrowing.
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F2
The neck CT was carried out to evaluate the thyroid mass with surrounding tissues, which revealed an extremely swollen thyroid with multiple enlarged cervical lymph nodes, some of which were larger than 6 cm, and some of which had obvious cystic changes and necrosis (Figures 2A,B). MR was used to evaluate the degree of stenosis of the cervical trachea and the need for a tracheal stent. MR images showed uneven signal values in the enlarged thyroid and lateral lymph nodes, and the tracheal compression and narrowing was obviously observed (Figures 2C,D).
PET/CT images of the patient. Increased 18F-FDG metabolism showed in the thyroid and cervical lymph nodes on the (A) transverse, coronal and (B) sagittal sections. The orange arrow indicated one of the cervical metastatic lymph nodes.
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F3
Next, PET/CT with 18F-fluorodeoxyglucose (18F-FDG) was performed to assess the extent of disease in the whole body due to the large mass, which showed extensive hypermetabolic lesions in the front of the neck and partial extension to the retrosternal space (Figure 3).
Gross and histopathological sections of follicular thyroid carcinoma and metastatic lymph node. (A) Gross image of follicular thyroid carcinoma. (B,C) H&E staining of follicular thyroid carcinoma (B, magnification x 40), black arrow indicated the vascular invasion of follicular thyroid carcinoma, the thyroid follicular epithelial cells were invaded into the blood vessel (C, magnification x 100). (D-J) Immunohistochemical (IHC) staining of follicular thyroid carcinoma (magnification x 200) for (D) TTF-1, (E) TG, (F) CK 7, (G) CK pan, (H) Ki 67, (I) calcitonin, (J) PTH. TTF-1 and CK7 were deeply stained (positive), TG and CK pan were partially stained (partial positive), Ki67 proliferation index was less than 1%, calcitonin and PTH didn't stain (negative). (K,L) H&E staining of neck metastatic lymph node: (K) magnification x 16, (L) magnification x 400. Yellow dashed circle indicated the amplification part in the picture K, black arrow indicated the normal part of the metastatic lymph node.
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F4
Then, a total thyroidectomy and cervical lateral and central lymph node dissection were undertaken; this whole thyroid was completely resected and weighted 623.2 g, which was almost 30-fold higher than normal thyroid weight (Figure 4A). The pathology report revealed a large diffuse infiltrative FTC with the longest diameter of 16.0 cm and more than 4 vascular invasion lesions (tumor cells invading a vessel wall indicates with a black arrow, Figure 4C), and nine cervical lymph nodes were removed and all of them showed metastatic involvement of FTC (Figures 4K,L). N1, M0). The immunohistochemical stains of FTC were positive for thyroid transcription factor (TTF-1) and cytokeratin (CK) 7, partially positive for thyroglobulin (TG) and CK pan, and negative for calcitonin and parathyroid hormone (PTH), and the Ki67 proliferation index was less than 1%, which is consistent with the diagnosis of angio-invasive FTC (Figures 4D-J). Next-generation sequencing (NGS) results revealed epidermal growth factor receptor (EGFR) and telomerase reverse transcriptase (TERT) promoter region (c.-124C > T) mutations with tumor mutational burden (TMB) of 2.13 mutations/Mb.