PMC10062477_01
Imaging and pathological findings. (A-C) Coronal T2-weighted MRI scans before treatment, after 2 courses, and after 5 courses; (D, E) Coronal high-resolution modified Dixon T1-weighted MRI scans of thyroid before and after 5 cycles; (F, G) Axial high-resolution modified Dixon T2-weighted MRI scans of thyroid before and after 5 cycles. The red arrows indicate the thyroid nodule. (H) Low magnification of PSCCT (H&E, x40) showed scattered islands of squamous cells (black arrows) with few typical follicular structures. (I) High magnification of PSCCT (H&E, x400) showed poorly differentiated tumor cells and typical nuclear heterogeneous cells (black arrows). (J) Low magnification of right lymph node metastasis (H&E, x40) showed diffuse proliferation of tumor tissue (red arrow). (K) High magnification of right lymph node metastasis (H&E, x400) showed epithelioid appearing neoplastic cells lacking differentiation, and abnormal mitotic figures (red arrow) could be seen. (L-S) Immunohistochemistry of the right lymph node metastasis (x40). P40 (L), P63 (M), CKH (N), and CK5/6 (O) were positive, indicating the source of squamous cells. CD56 (P) and CHGA (Q) are markers of neuroendocrine cells, while CK7 (R) is a marker of adenocarcinoma. Negative results suggested the low possibility of these two sources. (S) Ki67 index was over 95% suggesting vigorous proliferation excluding simple squamous metaplasia.
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Further MRI scans revealed a large right thyroid mass pressing on the airway ( Figures 1A, D, F ). The right lymph node revealed a small round epithelial malignancy with low differentiation, and pathological mitotic figures could be seen ( Figures 1H-K ). The results were consistent with squamous cell carcinoma ( Figures 1L-S ). Eli Lilly and Company) 200 mg once every 21 days. The patients were evaluated before every 3 treatment cycles. Surprisingly, after 2 courses, the volume of the tumor reduced significantly (maximum diameter from 11.17cm to 8.52cm,  Figure 1B ), and the symptoms of compression were relieved. Except for reversible leucopenia and skin pruritus, other laboratory tests were normal, and there were no other complications. MRI images showed almost no significant abnormalities in the original tumor site after 5 courses ( Figures 1C, E, G ).