PMC5902096_01
(a) Axial CT scan of the abdomen showing a mass lesion involving the inferior pole of the left kidney (arrow), breaching the renal capsule and infiltrating into adjacent retroperitoneal space. (b) Axial CT scan of the chest at the level of thyroid showing a well-defined hypodense nodule in the right lobe of the thyroid gland (arrow).
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Computed tomography (CT) of the chest and abdomen showed distal esophageal thickening along with incidental findings of solid mass lesion involving the inferior pole of the left kidney measuring 3.4 x 2.6 cm in the largest dimension (Figure 1) and a well-defined hypodense nodule in the right lobe of the thyroid gland measuring 2.1 x 2.8 cm in the largest dimension (Figure 1).
(a) Clear cells with increased vasculature consistent clear cell carcinoma of the kidney (40x, H&E). (b) Clear cell carcinoma invading renal vein (10x, H&E).
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Biopsy of renal mass was done which showed neoplastic cells with clear cytoplasm arranged in nests and mitotic figures suggesting clear cell carcinoma (Figure 2).
(a) Cell block (4x, H&E) of the thyroid showing atypical cells, which are PAX-8 positive (b) consistent with metastasis of renal origin.
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Fine-needle aspiration (FNA) from the thyroid nodule also identified neoplastic clear cells on cytology raising possibility of metastasis from RCC (Figure 3). PAX8 (Figure 3) and CAIX while negative for TTF-1. Positron emission tomography (PET) scans showed increased uptake in the distal esophagus, left renal mass, and right thyroid nodule.