We describe an unusual example of ovarian adenomatoid tumor that was an incidental finding in the ovary of a 52-year-old woman and was characterized by cells with abundant eosinophilic cytoplasm, an occasional feature of the adenomatoid tumor but one that, in an ovarian example, may cause added diagnostic confusion to that already engendered by the rarity of this neoplasm in the ovary. The typical numerous small vacuoles of the neoplasm sometimes had the appearance of signet ring cells. These 2 features (oxyphil and signet ring cells) caused a broad differential. Tumor cells were positive with broad-spectrum cytokeratins as well as mesothelial markers CK5/6, WT1, and calretinin. In reporting this case, we focus on the differential diagnosis of ovarian neoplasms and tumorlike conditions with vacuoles and related spaces, a topic that embraces many diverse entities.