Clinical Evidence for Adenoma-Carcinoma Sequence in Primary Retroperitoneal Mucinous Cystadenocarcinoma

Author(s): Atsuko Taga, Yukiyasu Sato, Shota Kanbayashi, Yasufumi Ri, Ikuko Emoto, Shunsuke Maruyama, Tomoyuki Shirase

Background: Adenoma–borderline tumor–carcinoma sequence, which was substantiated in the pathogenesis of ovarian mucinous carcinoma, could be extrapolated to that of primary retroperitoneal mucinous cystadenocarcinoma. Nevertheless, direct evidence is still insufficient due to its rarity.

Case: A 34-year-old Japanese woman with huge unilocular retroperitoneal cyst (16×8 cm) refused surgery. The cyst was gradually shrunken, measuring 10×4 cm at the age of 40. One year later, however, remarkable enlargement of the cyst (17×14 cm) with the emergence of three mural nodules was noted. The cyst was surgically removed intact. Histologically, a benign single layer of mucin-producing epithelial cells lined most of the cystic wall with focal microinvasive adenocarcinoma localized to the bases of mural nodules.

Conclusion: Primary retroperitoneal mucinous cystadenocarcinoma could arise from the pre-existing benign mucinous cystadenoma.