ABSTRACT
A spontaneous rupture into the sigmoid colon and peritoneal cavity is a most unusual complication for a mature cystic teratoma of the ovary. A 38-year-old woman with acute lower abdominal pain, presenting as peritonitis, visited our hospital. Physical examination revealed tenderness, rebound tenderness, and vague palpable mass in the right lower quadrant of the abdomen. A pelvic computed tomographic scan demonstrated a right ovarian cystic mass with bone and fat tissue, which had ruptured into the sigmiod colon, and peritoneal fluid collection. During a laparotomy, the ovary tumor was found to be densely adherent to the rectosigmoid junctional wall; also a solid element of the ovary tumor containg hair and skin tissue seemed to be in continuity with colonic lumen, and the ovarian wall was ruptured with spillage of purulent exudate into the peritoneal cavity. En bloc resection of the tumor-bearing segment of the sigmoid colon, together with the adherent right ovary and salpinx was carrried out. The diagnosis of a mature teratoma of the ovary was made by histologic examination of a surgical specimen; the tumor had perforated the sigmoid colon wall, had protruded into the bowel lumen, and had ruptured the intraperitoneal cavity due to inflammation its wall.