Figure 2: (a) Neoplastic cells forming papillary clusters with smooth contoured edges (b) Serous borderline tumor with hierarchically branched papillae lined by polygonal to columnar serous epithelium with mild atypia (inset) Immunohistochemistry showed (c) CK7 cytoplasmic positivity (d) PAX8 diffuse nuclear positivity (e) WT-1 diffuse nuclear positivity (f) CK20 negative staining.