case_images: PMC8155744_01
case_images: Contrast-enhanced computed tomography showing a lobulated hypodense mass in
  the spleen: (a) transaxial image; (b) coronal image.
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case_images: Computed tomography and magnetic resonance imaging indicated a huge lesion in the spleen (Figure 1).
case_images: (a) Whole-body 18F-fluorodeoxyglucose positron emission tomography
  demonstrating high tracer accumulation only in the spleen. (b) Fused
  positron emission tomography/computed tomography images of the cross section
  of the spleen showed hot spot (maximum standard uptake value = 5.5).
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case_images: There was no abnormal increase in glucose metabolism in parts other than the spleen according to whole-body 18F-fluorodeoxyglucose positron emission tomography (Figure 2).
case_images: Macroscopic view of the resected spleen. A white-gray, well-defined mass
  containing necrotic areas, 130 x 120 x 90 mm in size, showing an expansive
  growth pattern in the spleen.
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case_images: The tumor was a white-gray, well-defined mass containing necrotic areas and measured approximately 130 x 120 x 90 mm with an expansive growth pattern (Figure 3).
case_images: Hematoxylin and eosin staining of the splenic tumor neoplastic cells showing
  a papillary pattern with necrotic tissue and a psammoma body (arrow) (a,
  x100). Pleomorphic and hyperchromatic nuclei were observed (b, x200).
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case_images: The representative features are shown in Figure 4.
case_images: Immunohistochemical staining of the tumor cells for cytokeratin 7 (a, x200),
  cytokeratin 20 (b, x200), PAX-8 (c, x200), WT-1 (d, x200), p53 (e, x200),
  and Ber-EP4 (f, x200).
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case_images: Ber-EP4 (Figure 5(f)) but negative for CK20 (Figure 5(b)), thyroid transcription factor-1, carcinoembryonic antigen, CD10, estrogen receptor, calretinin, D2-40, intelectin-1, and sialylated HEG1. Based on these findings, we diagnosed the tumor as a serous carcinoma.