case_images: PMC8641443_01
case_images: (A) Low-power view showing a submucosal tumor with relatively clear boundaries (hematoxylin and eosin, H&E, 2x magnification). (B) High-power view of the tumor showing a syncytial cytoplasmic appearance and abundant intratumoral immune infiltration (H&E. 10x and 40x magnification).
case_images: fmed-08-766960-g0001.jpg
case_images: PMC8641443_01_fmed-08-766960-g0001.jpg
case_images: F1
case_images: The submucosal tumor showed a lymphoepithelioma-like growth pattern (Figure 1).
case_images: Immunohistochemistry and ISH. (A) The tumor was diffusely positive for CK5/6 (A), and negative for CK20 (B). (C) Immunostaining for p16 was diffusely positive, and (D)
  in situ hybridization (ISH) for Epstein-Barr virus-encoded small RNA was negative (D). (E) Strong PD-L1 positivity and (F) abundant CD8+ T cell infiltration were observed. [(A-D), 4x magnification; (E,F), 20x magnification].
case_images: fmed-08-766960-g0002.jpg
case_images: PMC8641443_01_fmed-08-766960-g0002.jpg
case_images: F2
case_images: Immunohistochemically, the tumor cells were positive for pan-CK, P63, P40, and CK5/6 (Figure 2A), and negative for SATB2, Villin, CDX2, and CK20 (Figure 2B). Diffuse block-type immunoreactivity (diffuse nuclear and cytoplasmic staining) of p16 was shown (Figure 2C). The tumor cells were negative for EBER, while strongly positive staining was observed in the external positive control (Figure 2D). The immunostaining intensity of PD-L1 was evaluated by the combined positive score (CPS), and a strong immunoreaction was observed with a CPS > 70 (Figure 2E). We also analyzed the presence of intratumoral CD8+ T cells and found that abundant tumor-infiltrating lymphocytes (TILs) were CD8-positive (Figure 2F).