Some mullerian inclusion cysts in lymph nodes may sometimes be metastases from serous borderline tumors of the ovary

Glandular inclusions that appear morphologically benign are occasionally fo und in lymph nodes as well as in peritoneal and omental biopsies. In patien ts with gynecologic malignancies, the nature and significance of these mull erian inclusion cysts (MIC) present a diagnostic challenge with regard to w hether they are benign and incidental or are related to the coincident tumo r for which surgery is being performed. Sixty-two cases of MIC were prospec tively identified during a 6-year period. The frequencies were calculated a nd stratified by lymph node chain distribution primary tumor site, and prim ary tumor type. MIC appeared as small cysts lined by a serous (mullerian)-t ype, cytologically bland, cuboidal to columnar epithelium with a simple arc hitecture. Among 62 women, MIC was found in lymph nodes (27 cases), pelvic peritoneum (19 cases), omentum (16 cases), bowel serosa (9 cases), uterine serosa (8 cases), and parametrial connective tissues (4 cases). Among a set of 417 consecutive cases in which lymphadenectomy was performed, 46 (11%) women had MIG. The MIC involved multiple sites (26 cases in the peritoneum/ omenturn and 27 in lymph nodes). The primary turner was in the ovary in 32 of the 46 women with MIC (70%) and of these, 17 were borderline serous (53% ). Sixty-two of 6154 lymph nodes examined contained MIC (1.0%). 3.2% of nod es contained MIC in which the primary tumor arose in the ovary, but only 0. 1% with either endometrial or cervical tumors (chi(2), P<0.00001). The lymp h nodes most often involved by MIC were from para-aortic sites (40%), which reflect the primary drainage route from the ovary. Not uncommonly, neighbo ring areas in the same lymph node group with MIC disclosed separate foci of obvious metastatic borderline tumor (4 of 10; 40%). In summary, the increa sed frequency of MIC in lymph nodes sampled for primary ovarian malignancie s suggests that MIC in some cases, rather than being benign, incidental inc lusions, are more likely bland-appearing forms of metastatic tumor. The pre ponderance of inclusions occurs with serous ovarian tumors of borderline ma lignancy, and the inclusions are overrepresented in the lymph nodes that pr imarily receive drainage from the ovary.