Gastrointestinal stromal tumor of the lesser omentum in a young adult patient with a history of hepatoblastoma: report of a case.

A gastrointestinal stromal tumor (GIST) of the lesser omentum is extremely rare. This report presents a case of GIST of the lesser omentum in a 22-year-old man with a history of hepatoblastoma. Computed tomography showed an abdominal mass about 30 mm in diameter adjacent to the lesser wall of the stomach. A laparotomy showed a mass of about 27 x 24 x 20 mm in diameter originating from the lesser omentum but isolated from the stomach and the liver. Histopathology showed that the tumor was composed of spindle-shaped tumor cells with high cellularity. Immunohistochemically, the tumor was positive for KIT and CD34. An in-frame deletion was observed in the c-kit gene exon 11. Therefore, the tumor was diagnosed as a GIST originating from the lesser omentum.