Fig. 2

Gross and microscope observations. A protruding mass with white cut surface in the gastric antrum and many fundic gland polyps diffusely distributed in the cardia and body of stomach (a). Microscopic section of the mass characterized by spindle cells arranged in a fascicular pattern with prominent chronic inflammatory cell infiltrates (b, H&E stain, ×40). High power microscopy of spindle-shaped cells admixed with infiltrating lymphocytes and plasma cells (c, H&E stain, ×100). The tumor cells were positive in cytoplasm for smooth muscle actin (SMA) (d) and anaplastic lymphoma kinase (ALK) (e) (Immunohistochemical stain, ×100, right bottom ×200). Five of 19 lymph nodes adjacent to stomach contain metastatic tumor cells (f, H&E stain, ×100; g, ×200), and were positive for ALK (h, Immunohistochemical stain, ×100; i, ×200). Fluorescent in situ hybridization analysis of ALK rearrangement in inflammatory myofibroblastic tumor using Vysis break apart probe kit (j, 1000×) and chromogenic in situ hybridization analysis of Epstein-Barr virus-encoded small RNAs using Leica Bond ready-to-use probe in inflammatory myofibroblastic tumor (k, 1000×) and nasopharyngeal carcinoma as positive control (l, 1000×)