Fig. 1.

A. Serous borderline tumor with micropapillary features. The tumor is comprised of large papillae with well-developed fibrovascular cores (black asterisks) surrounded by thin, delicate papillae with length > 5 times the width and scanty fibrovascular support (white asterisks). The area of micropapillary growth pattern spans > 5 mm in diameter. B. Invasive implant. The tumor consists of irregular to round glands of varying size (black asterisks), haphazardly infiltrating dense fibrous stroma (white asterisk), and surrounded by clear spaces. Some glands exhibit micropapillary (black arrowheads) or cribriform architecture (white arrowhead). The glands contain serous and mesothelial-type cells with moderate cytologic atypia. C. Non-invasive desmoplastic implant. Irregular gland-like structures (black asterisks) are embedded in an abundant inflamed and edematous (granulation tissue-like) stroma (white asterisk) in a linear orientation. The gland-like structures are lined by one to several layers of epithelial and mesothelial-type cells displaying abundant eosinophilic cytoplasm and mild cytologic atypia. (hematoxylin & eosin stain; original magnification × 100 [all panels]).