PMC8281219_01
T2-weighted magnetic resonance imaging (MRI) showed irregular pancreatic mass measuring 105 mm in the maximum diameter.
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The T2-weighted magnetic resonance imaging (MRI) showed varying degrees of low-intensity lesions outside the tumor in the pancreatic neck and heterogeneous high-intensity lesions within the tumor ( Figure 1 ).
PET-CT scan demonstrated a mass measuring 105 x100 x 70 mm with peripheral elevated FDG avidity in the neck of the pancreas.
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PET/CT examination of f-fluorodeoxyglucose (F-FDG) showed high coalescence of FDG at the site of the pancreatic neck mass with a maximum standardized uptake value (SUV max) of 26.7, while the SUV max of the surrounding lymph nodes was 30.6 ( Figure 2 ).
(A) Histological findings revealed a pancreatic squamous cell carcinoma (SCC) with abundant eosinophilic cytoplasm and large vesicular nucleus. (HE x 200). (B) Immunohistochemical staining of PD-L1 expression. Original magnification, x200. (C) T2-weighted magnetic resonance imaging (MRI) showed the mass decreased to 55 mm in the maximum diameter. (D) T2-weighted magnetic resonance imaging (MRI) showed the mass measured 16mm after 2 cycles of intra-arterial chemotherapy.
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A percutaneous biopsy of the pancreatic tumor was performed under CT guidance, and pathological histology shows squamous cell carcinoma with distinct keratinized features, abundant eosinophilic cytoplasm, and large vesicular nuclei ( Figure 3A ). PD-L1 protein was evaluated with an immunohistochemical method using a mouse monoclonal anti-human PD-L1 antibody (Clone 22C3, Dako). PD-L1 positive tumor cells within the tumor tissue specimen was 90% ( Figure 3B ), the expression of MSH2, MLH1, MSH6, and PMS2 were positive. Then, Sindilimab monotherapy was administered every three weeks, and repeated MRI imaging showed the mass had shrunk to 5.5 cm after seven cycles of single immunotherapy ( Figure 3C ). MRI of the upper abdomen showed that the tumor regressed to 1.6 cm 1 month after two intra-arterial infusion therapy cycles ( Figure 3D ).
(A) Immunohistochemical staining of CK5/6 expression. Original magnification, x200. (B) Immunohistochemical staining of CK19 expression. Original magnification, x200. (C) Immunohistochemical staining of p63 expression. Original magnification, x200. (D) Immunohistochemical staining of GATA-3 expression. Original magnification, x200. (E) Immunohistochemical staining of negative CK20 expression. Original magnification, x200. (F) Immunohistochemical staining of negative CDX2 expression. Original magnification, x200. (G) Immunohistochemical staining of negative Syn expression. Original magnification, x200. (H) Immunohistochemical staining of negative Cg A expression. Original magnification, x200. (I) Immunohistochemical staining of negative TTF-1 expression. Original magnification, x200.
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TTF-1, CK20, CDX2, CgA, and Syn were negative ( Figures 4A-I ).