KEY WORDS: intussusception; sigmoid lipoma; mimicking carcinoma.Colonic lipomas are the most common nonepithelial tumor, and they are the third most common tumor, after hyperplastic and adenomatous polyps (1). The majority of colonic lipomas are small and asymptomatic (2). Large lesions may be significant because of their related symptoms, and especially, intussuscepted colonic lipomas are often confused with malignant tumors, so that most of them are diagnosed after intervention (3). We present a case of an intussuscepted lipoma mimicking a malignant tumor in a 62-year-old man. Intussuscepted colonic lipoma is uncommon, and a right-side intussuscepted colonic lipoma is especially rare. The malignant transformation of lipoma is extremely rare, and recurrent lipoma has never been reported. Nonetheless, operative or endoscopic intervention may be required to differentiate this lesion from a malignant or premalignant lesion. This case is very unique in the aspects of the lipoma's shape and size and the location in which it was found. CASE REPORTA 62-year-old man was admitted to the hospital because of left lower quadrant abdominal pain that had lasted for 1 month, with intermittent hematochezia. The patient said he did not have any fever or weight loss. Upon physical examination, he had pale conjunctiva, and there was left lower quadrant tenderness without rebound tenderness. There was also a relatively highpitched sound on abdominal examination. The rectal examination showed dark blood-tinged stool. The other findings from the physical examination were normal. The results of laboratory investigation, including the level of carcinoembrionic anti-

We report a rare case of deciduoid peritoneal mesothelioma in a 47-year-old woman who had no history of asbestos exposure or previous surgery. Immunohistochemistry and electron microscopic findings showed that the tumor was a subtype of epithelioid mesothelioma. Awareness of this disease entity is helpful for the differential diagnosis of peritoneal masses.