A case of retroperitoneal mucinous cystadenoma histologically confirmed in
a 21-year-old woman is reported. Although ultrasound, CT and MR detected th
e tumor, a preoperative diagnosis could not be established by imaging metho
ds. The cystic tumor was removed and microscopic examination revealed a muc
inous cystadenoma, Mullerian mesothelial metaplasia of peritoneal invaginat
ion into the retroperitoneal space is the most likely explanation for the h
istogenesis of these tumors. (C) 1999 Elsevier Science Ireland Ltd. All rig
hts reserved.