SYP and neoplasm: Immunostaining of the tumor cells revealed the following: strong and diffuse positivity for SATB2, INSM1, and synaptophysin immunostaining; patchy positivity for keratin AE1/3 (dot-like pattern), keratin CAM5.2, and keratin 20 immunostaining; and negative for CD45 (LCA), S100, SOX10, keratin 7, TTF1, CDX2, and chromogranin immunostaining, and mucicarmine special stain (Figure 3).