Mesenteric fibromatosis successfully resected with duodeno-jejunectomy and nephrectomy.

We report a rare case of intra-abdominal fibromatosis of the jejunal mesentery. A 71-year-old man, who was incidentally diagnosed with left hydronephrosis, was found to have a tumor near the duodeno-jejunal junction. The tumor appeared to invade the intestinal wall and was obstructing the left ureter. The tumor was indefinite in diagnosis preoperatively. The patient underwent an en-bloc excision of the tumor by a partial duodeno-jejunectomy combined with a left nephrectomy. Microscopic examination of the tumor showed that non-dysplastic fibroblasts proliferating in the jejunal mesentery had infiltrated into the adjacent small intestines and ureter, resulting in a diagnosis of intra-abdominal fibromatosis. This diagnosis was supported by findings of immunohistochemical analyses showing positive staining for vimentin and smooth muscle actin and negativity for keratin, CD34, C-kit and S-100. To our knowledge, this is the first documented case of intra-abdominal fibromatosis of the jejunal mesentery completely resected with the operative procedure described herein. In cases of a preoperatively undiagnosed retroperitoneal or mesenteric tumor that invades adjacent structures, it is important to consider intra-abdominal fibromatosis as a possible differential diagnosis. This may be helpful in planning the appropriate therapeutic strategies including extended multi-organ resection in selected patients.