Signet-ring stromal tumor of the ovary: clinicopathologic analysis and comparison with Krukenberg tumor.

Signet-ring stromal tumor is a rare ovarian neoplasm that can mimic Krukenberg tumor because of the presence of signet-ring cells in both tumors. The clinicopathologic features of three signet-ring stromal tumors, one of which has been previously reported, were analyzed and compared with 10 Krukenberg tumors. Patients with signet-ring stromal tumor ranged in age from 34 to 41 years (mean: 36.7 years). All signet-ring stromal tumors were unilateral and stage IA, whereas 60% and 40% of Krukenberg tumors were bilateral or associated with extraovarian tumor, respectively. The signet-ring stromal tumors were devoid of epithelial differentiation (glands, nests, cords), whereas all of the Krukenberg tumors contained these epithelial structures at least focally. In contrast to signet-ring stromal tumors, the signet-ring cells of Krukenberg tumors were positive for periodic acid-Schiff with diastase and cytokeratins but negative for vimentin. The patients with signet-ring stromal tumors were alive without disease at follow-up interval of 1 month to 17.4 years (mean: 7.4 years). In summary, signet-ring stromal tumor is a rare, benign, ovarian tumor that may be mistaken for Krukenberg tumor. Although the combination of operative and histopathologic findings allow their distinction, histochemical and immunohistochemical stains may also be useful.