Macroscopic and microscopic findings of the resected specimen (case 1). (A) The gross appearance of the tumor. Macroscopically, the whole lesion was 130 x 90 mm in size in the resected specimen. The image of the lesion is illustrated as an inset in the lower right. The letters (a), (b), and (c) denote separated cystic lesions and correspond to those in Figure 1B. The medial side of the cyst wall of cyst (b) and the septum between the cysts (a) and (b) are lost in the specimen. There is a papillary mass in the posterior side of lesion (b) (indicated by arrows). The lesion (c) is filled with solid components. (B) A loupe observation of the solid component surrounded by a white line in (A) (hematoxylin and eosin). A papillary nodular mass (indicated by arrowheads) is seen inside of the cyst wall. (C) A magnified observation of the point encircled in (B) (x20, hematoxylin and eosin). Arborizing papillae with thin- walled vessel are seen. The lesion is lined by multilayers of cuboidal to columnar cells with abundant eosinophilic cytoplasm forming intraepithelial lumina (some of the lumens are indicated by asterisks (*)). The tumor cells had sufficient cytoarchitectural atypia to be classified as having high-grade dysplasia. (D) (E) A magnified (x20) image of the cyst wall (hematoxylin and eosin in (D)) and immunohistochemical staining for progesterone receptor in (E). The cyst wall is indicated by a double arrow. Tumor components consisting of multilayer cuboidal to columnar cells (upper side of the cystic wall in the picture, inside of the tumor) and normal hepatocytes (lower side of the cystic wall in the picture, outside of the tumor) are seen. No ovarian-like stromata were seen throughout the cyst walls.