RÉSUMÉ
Aggressive Angiomyxoma is a rare, benign but locally aggressive mesench ymal neoplasm, predominently involving the pelvis and perineum of young omen. We experienced a case of aggressive angiomyxoma in the retroperitoneum. A 47-year-old woman patient visited our hospital because of constipation and an abnormal intraabdominal mass in routine examination. Examination by abdominal ultrasonography and MR imaging indicated that it was a well capsulated large soft tissue tumor in the retroperitoneum. Thus, she underwent excision of the retroperitoneal tumor. A 15 x 10 x 2 cm yellow-whitish mass was noted. The cut surface was homogenous, tannish yellow and mucoid. Microscopic findings represent that a mass was composed of widely scattered spindle-shaped and stallate-shaped cells and variable sized vascular channels within a myxoid matrix. So we report this case with a review of literature.