Serous borderline neoplasm

(A) Serous borderline neoplasm with an epithelial proliferation of low-grade cells with serous morphology. Note the epithelial stratification and the hierarchical branching of successively smaller papillae arising from larger, more centrally located papillae.
(B) Higher power of serous borderline neoplasm. Note lack of any invasion.
(C) Serous borderline neoplasm with proliferative epithelium and low-grade nuclei lining papillae.