Primary ovarian adenofibromatous neoplasms with mucin-containing signet-ring cells: a report of 2 cases.

The presence of mucin-containing signet-ring cells in an ovarian neoplasm is considered strong evidence for a metastatic rather than primary tumor. The clinicopathologic features of 2 ovarian adenofibromatous neoplasms with mucin-containing signet-ring cells (AFN-SRs), proven by the long-term follow-up of 10 and 15 years to be primary tumors, are presented as exceptions to this general guideline. Both of these tumors were initially strongly favored to be metastatic adenocarcinoma by expert consultants in gynecologic pathology, which underscores the diagnostic difficulty that these rare and unusual neoplasms can pose. Although long-term follow-up of AFN-SRs is still necessary to exclude the possibility of metastases, the following constellation of features can correctly suggest a primary neoplasm rather than a Krukenberg-like metastatic process at the time of presentation: (i) the appearance of fibromatous stroma as an integral part, as opposed to reactive part, of the neoplasm, (ii) a semiorganized rather than completely haphazard pattern to the placement of the epithelial elements, with a circumscribed noninfiltrative interface with ovarian parenchyma, (iii) the absence of angiolymphatic invasion, (iv) tumor unilaterality, and (v) the lack of a known primary source. The virtual absence of literature on these low-grade malignancies, coupled with the occurrence of 2 such tumors within a 7-year period at a single community hospital, suggests that many AFN-SRs continue to be misdiagnosed as metastatic adenocarcinoma.