Hiroshi Takahashi, Toshiya Morimura, Rie Ikeda, Hironobu Yonekawa, Akinari Hinoki, Masato Sakai, Hideaki Murai, Takemaru Tanimizu, Shigeki Takahashi, Akio Odaka^1）,
Akira Satomi

Department of Pediatric Surgery, Saitama Medical School
Department of Surgery, Saitama Medical School General Medical Center^1）

　　We report a case of a giant great cyst in the abdominal cavity.
　　The case was a 1-year 6-month-old girl. She was found to have abdominal distension on medical checkup. Her general condition was unexpectedly good. Her blood data were normal except CA19-9, which was slightly high.
　　Ultrasonography of her abdomen showed a giant cyst. MRI confirmed multilocular cysts in her abdominal cavity, but we could not identify the primary lesion. On surgery, diagnosed great omental cyst, and considered that it was a lymphangioma.
　　In the literature, great omental cyst ,is unusual amounting to 2％ of all abdominal cyst. The pre-surgery diagnosis rate is 4 to 7％. The cysts are usually multilocular, and found on boys aged under ten. But in the foreign literature, great omental cyst is usually unilocular.
　　We think that great omental cyst is very important for differential diagnosis, because this cyst sometimes leads to acute abdomen.

Keywords：Giant Great omental cyst, Primary legion, MRI, Ultrasonography