Fig. 2

Histopathological features of the tumor. Microscopically, the tumor consisted of a classical acinic component and a solid high-grade component (A, H&E, 20×). SOX10 (B, EnVision, 20×) staining highlighted the distribution of the two components. The acinar architectures arranged irregularly were composed of one to several layers of neoplastic epithelial cells (C, H&E, 200×). There were no myoepithelial cells or basal lamina, and neoplastic glands were focally surrounded by a capillary network (D, H&E, 400×). Between both components, acinic architectures merged together into small solid or cribriform nests, and the number of stromal tumor-infiltrating lymphocytes was high (E, H&E, 100×; F, H&E, 200×). The transition from neoplastic glands or confluent nests to the large solid region (G, H&E, 100×; H, H&E, 200×; I, H&E, 400×) and the faint outline of the remaining glands in the high-grade lesion (I, H&E, 400×) were observed