Fig. 2

Gross and histological appearance of the tumor. A Gross findings (before formalin fixation) of cutting surface are shown. Similar to imaging findings, the tumor shows a multicystic appearance. Each cyst is separated by a slightly thick septum. Cut surface of the solid area is a heterogeneous tan-brown in color without hemorrhage or necrosis (white arrows). B Microscopically, tumor cells with hyperchromatic nuclei and scanty cytoplasm proliferate in sheets (hematoxylin and eosin staining[H&E], 100×). C Three types of the tumor cells are shown. Tumor cells with eosinophilic cytoplasm (Leydig cell tumor-like appearance, black arrow) and tumor cells with clear to slightly eosinophilic cytoplasm (Sertori cell tumor-like appearance, white arrow) proliferate in nests or tubular formation. And tumor cells with scanty cytoplasm (adult-type granulosa cell tumor-like appearance, lower right) are observed (H&E, 400×). The tumor cells with nuclear grooving are scattered (inset, arrow heads). D–F. The majority of the tumor cells are positive for calretinin (D, 100×), alpha-inhibin (E, 100×). Tumor cells with scanty cytoplasm and grooved nuclei are positive for CD56 (F, 100×), which is consistent with adult-type granulosa cell tumor. G, H. Tumor cells with clear cytoplasm are seen in part (G, arrows; H&E, 100×). The tumor cells show distinct nucleal staining of beta-catenin, suggesting a Sertoli cell tumor (H, arrows, 100×), whereas tumor cells with eosinophilic cytoplasm suggesting a Leydig cell tumor (G, arrow heads) show negative nucleal staining for beta-catenin