PMC7171659_01
CT and PET-CT findings. (a) Computed tomography showing a 27 mm lump on the right side of the upper mediastinum that is invading the superior vena cava. (b) PET-CT showing metastasis of the lumbar vertebrae.
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An enhanced computed tomography (CT) scan showed a 27 mm lump on the right side of the upper mediastinum, stenosis of the superior vena cava, and dilation of surrounding collateral vessels (Figure 1(a)). Positron emission tomography-computed tomography (PET-CT) showed accumulation in the upper mediastinal tumor (SUVmax = 5.18), the left 1st and 4th ribs (SUVmax = 5.48), and lumbar vertebrae L1 and L2 (SUVmax = 7.64), but no hot spot in the thyroid (Figure 1(b)).
Bone biopsy results of the lumbar vertebrae. HE staining showing a papillary structure and positive immunohistochemistry for thyroglobulin. (a) HE staining x100. (b) Immunohistochemistry for thyroglobulin x100.
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A bone biopsy of the lumbar vertebrae revealed atypical epithelial cells with a follicular structure and nuclear groove on HE staining, and immunostaining was positive for thyroglobulin and PAX-8 (Figure 2), indicating the presence of a bone metastasis of papillary thyroid carcinoma.
PMC7171659_02
CT images. (a) 7.2 cm mass in the anterior mediastinum. (b) Pulmonary metastasis.
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We could not confirm continuity with the thyroid; we found no lymph node metastases (Figure 3). A PET-CT showed accumulation in the upper mediastinal tumor (SUVmax = 46.32) and pale nodules in the left lower lobe (SUVmax = 5.23; Figure 3).
Pathology results for a tumor. Mediastinal tumor growing in papillary shape with a fibrotic capsule. Tumor cells have nuclear groove and inclusion body (HE staining). (a) x20. (b) x400.
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The pathological report suggested a papillary carcinoma because of the preponderance of papillary growth and the presence of a papillary carcinoma nucleus (nuclear groove; Figure 4).
PMC7171659_03
Left lateral cervical lymph node imaging. Neck ultrasonography (a) and CT scan (b) images showing cervical lymph node swelling.
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Contrast-enhanced CT showed a hepatic hemangioma only, without findings suggesting a primary site (Figure 5).
Microscopic pathology slides of left cervical lymph nodes. (a) Left cervical lymph nodes had nuclear findings of papillary thyroid carcinoma. (b) 1 mm papillary carcinoma tumor in the left lobe (HE staining x100).
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The metastatic lymph nodes had nuclear findings of papillary thyroid carcinoma (Figure 6).