PMC8077592_01
Preoperative imaging. a Cervical ultrasonography shows a low echoic and unclear solid mass in the lower pole of the left thyroid lobe. b CT image reveals a low-density mass in the left thyroid lobe. c Positron-emission tomography shows 18F-FDG accumulation in the left thyroid tumor (standardized uptake value of 5.29).
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F1
Ultrasonography revealed a hypoechoic solid mass in the lower pole of the left thyroid lobe with a poorly marginated heterogeneous pattern (Fig. 1a). Computed tomography revealed a heterogenic tumor in the left thyroid lobe (Fig. 1b). 18F-fluorodeoxyglucose (18F-FDG) accumulated in the thyroid tumor on positron-emission tomography. The standardized uptake value of 18F-FDG was 5.29 (Fig. 1c).
FNAC shows numerous lymphoid cells without atypia.
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F2
Fine-needle aspiration cytology (FNAC) showed a number of lymphoid cells without atypia that were similar to those seen in malignant lymphoma of the thyroid (Fig. 2).
Histological findings. a Thick fibrous septa intersecting the tumor cells into lobules. Hematoxylin-eosin stain, x40. b Tumor cells have a round nucleus with remarkable nucleolus. Hematoxylin-eosin stain, x400. Immunohistochemical studies showed the tumor was CD5 partially positive (c) and Ki-67 positive (d).
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F3
Histopathological findings showed that the tumor was composed of irregular insular nests of neoplastic cells and had an expansive growth pattern in the thyroid (Fig. 3a). The carcinoma cells had round nuclei or polymorphonuclei with well-defined nucleoli and ill-defined cell borders (Fig. 3b). Immunohistochemical studies showed that the tumor was partially positive for CD5, positive for Ki-67 (approx. 30%), and negative for CD20, calcitonin, and thyroglobulin (Fig. 3c, d).