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case_images: Facial features of the patient with NKTCL. (A) Two years before diagnosis. (B) At the time of diagnosis of NKTCL. (C) Mucosal ulcer in the inner lower lip at diagnosis. (D) After completing 3 cycles of P-GemOx regimen chemotherapy. (E) After one cycle of sintilimab and decitabine combination treatment. (F) After four cycles of sintilimab and chidamide combination treatment.
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case_images: At his first visit, a 24-year-old young man stated that two years ago his face, especially eyelids, was slightly red and swollen without any discomfort ( Figure 1A ). Physical examination revealed that his whole face was red and swollen with a mucosal ulcer in the inner lower lip ( Figures 1B, C ). However, there was no further improvement for the facial swelling following the third cycle of chemotherapy ( Figure 1D ) and the plasma EBV-DNA titer came back and was increased to 1.15 x 103 copies/ml, indicating the development of acquired resistance to pegaspargase-based chemotherapy. Unexpectedly, the patient's facial swelling was slightly aggravated ( Figure 1E ), accompanied by the reappearance of fever, and the plasma EBV-DNA titer was increased to 7.02 x 103 copies/ml. After four cycles of the combined treatment, the patient's facial swelling had subsided, and he looked totally normal ( Figure 1F ).
case_images: Microscopic and immunohistochemical features of NKTCL tumor. Histological examination of H&E-stained tissues shows infiltration of medium-sized cells with irregular nuclei and inconspicuous nucleoli. Immunohistochemical staining shows positive CD3, CD56, TIA-1, and granzyme B, focally positive CD8, and negative CD20. Ki-67 proliferation index was about 90%. In situ hybridization for EBV-encoded RNA (EBER) reveals positive reaction. Original manifestation 400x.
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case_images: In situ hybridization revealed EBV infection in the majority of neoplastic cells ( Figure 2 ).
case_images: Face imaging features of the patient at diagnosis. (A-D) PET/CT shows thickened and FDG-avid midline facial skin. (E, F) MRI sagittal plane and horizontal views show thickened facial skin and hyperintensity on T2-weighted imaging.
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case_images: Positron emission tomography-computed tomography (PET/CT) ( Figures 3A-D ) and magnetic resonance imaging (MRI) ( Figures 3E, F ) showed that the facial soft tissues, eyelids, and lips were swollen with hypermetabolic activity (SUVmax 10.3).
case_images: Treatment process and the changes of plasma EBV-DNA titers.
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case_images: A detailed treatment process and the changes of plasma EBV-DNA titers are shown in  Figure 4 .