case_images: PMC11061524_01
case_images: Abdominal computed tomography scan + enhancement show a primarily solid, mixed-density mass in the pancreatic head area, with significant enhancement of the solid component, interspersed low-attenuation foci, and visible tortuous small vessels within. (A) Pre-contrast phase; (B) Artery stage; (C) Portal vein stage. : Tumor; : Visible tortuous small vessels; : Interspersed low-attenuation foci.
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case_images: Upon enhancement, the mass demonstrated heterogeneous enhancement, with the solid component significantly enhanced, interspersed with a few low-attenuation foci, and tortuous small vessels could be seen within the mass ( Figures 1A-C ).
case_images: (A) The positional relationship between the tumor and the artery.  : Celiac trunk;  : Superior mesenteric artery;  : Right renal artery. (B) The positional relationship between the tumor and the portal vein.  : Portal vein; :Superior mesenteric vein. (C) The tumor's positional relationship with the inferior vena cava and right renal vein. : Right renal vein;  : Inferior vena cava. (D) The positional relationship between the tumor and the adjacent organs. : Duodenum;  : Right kidney.
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case_images: This technique also enabled individual analysis and assessment of the arteries, veins, and organs surrounding the tumor, facilitating an evaluation of the tumor's resectability ( Figures 2A-D ).
case_images: Postoperative gross specimen.
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case_images: The postoperative gross specimen is depicted in  Figure 3 .
case_images: Gross resection of the visible tumor. : Portal vein; : Common hepatic artery. : Superior mesenteric vein. The pancreatic cut surface after tumor resection.
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case_images: All visible tumor within the operative field was excised during the surgical procedure ( Figure 4 ).
case_images: (A) Small round-cell malignant tumor (HE,100x). (B) Positive immunohistochemical staining for CD99(100x). (C) Positive immunohistochemical staining for NKX2.2 (100x). (D) Positive immunohistochemical staining for Syn (100x).
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case_images: The pathology report from Fudan University Shanghai Cancer Center confirmed that the tumor, located in the head of the pancreas, was identified as Ewing's sarcoma ( Figure 5A ) and invaded the full thickness of the small intestine and colon. The immunohistochemical assay revealed positivity for Vim, CD99( Figure 5B ), NKX2.2( Figure 5C ), SE (partially), Syn( Figure 5D ), CgA (small focus), Ki-67 (approximately 60% in hotspot areas), INI-1, B-catenin (cytomembrane), and CK, negativity for Desmin, Myogenin, MyoD1, CD3, CD20, CD45, EMA, WwT1, Fli-1, and ERG.