Fig. 2.

Small flattened or cuboidal tumor cells proliferate with stroma and usually form papillary structures that are more tightly-packed in the inner parts of the tumor mass (B) than in the free surfaces (A). The stroma is mostly hyalinous and often small and round. Psammoma bodies are observed at the centers of some stromata (arrows). Although shown in B, psammoma bodies were also present in the inner parts. C. Tumor cells with a stroma are also observed in the alveolar septa. HE. Bars=20 μm.