FIGURE 3
A, Histologically, the cyst wall is composed of dense fibrous tissue, while no mesenchymal stroma is recognizable. There is marked papillary neoplastic proliferation (arrows) of the lining epithelia with fibrovascular cores in the cystic lesion. L, lumen of cystic space. HE, × 40. B, The papillary structure of this tumor is evident. The neoplastic epithelia with acidophilic cytoplasm cover the papillae, and the stroma of these papillae are edematous and myxoid (*). The neoplastic epithelia are artificially desquamated. L, bile duct lumen. HE, × 150. C, The cystic walls are lined by multilayered cuboidal to low columnar epithelial cells. The epithelial cells show atypical nuclei with nucleoli and an eosinophilic granular cytoplasm. HE, × 400. D, E, In solid areas, tumor cells with an acidophilic granular cytoplasm are floating in a mucinous substance (D), or embedded in loose fibrous tissue (E). They form small glands, acini, or small solid nests. D, HE, × 200; E, HE, × 200
