PMC9633570_01
(A). The maximum intensity projection (MIP) image of the patient who had undergone post-right nephrectomy shows abnormal sites of uptake in a right arm lesion (target spot) and multiple lung nodules (red arrowheads). (B) The lesion in the subcutaneous soft tissue of right arm is noted as a low-density nodule on CT (C) with abnormal uptake on 18F-FDG PET-CT.
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A positron emission tomography-computed tomography (PET-CT) scan showed a right-arm lesion and multiple lung lesions due to abnormal 18F-FDG uptake (Fig. 1).
(A) Superficial ultrasound of the right arm shows an oval, hypo-echoic nodule with well-defined margins and no shadowing in the subcutaneous fat. (B) Extensive vascularity is noted.
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Superficial ultrasonography of the right arm revealed a solid hypo-echoic nodule approximately 17 mm x 9 mm in size with an oval shape, smooth edges, and a well-defined boundary in the subcutaneous fat (Fig. 2A). Color Doppler flow imaging revealed rich blood flow in the nodule (Fig. 2B).
Renal clear cell carcinoma metastasis to the right arm. (A, B) Metastatic clear cell RCC (hematoxylin-eosin, original magnification 10x & 40x). (C) The neoplastic cells show strong nuclear staining with PAX-8 (immunohistochemistry, original magnification 40x). (D) Diffuse and strong cell cytoplasm staining for vimentin is observed in the neoplastic cells. Positive cells display brownish yellow granules on the surface, cytoplasm, and intercalated disks (immunohistochemistry, original magnification 40x). (E, F) The neoplastic cells show strong membranous staining with CA-IX and CD10 (immunohistochemistry, original magnification 40x).
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Pathological results, morphology, immunohistochemical results, and clinical history supported the metastasis of renal clear cell carcinoma (Fig. 3).