Background: Fibromatosis is a kind of spindle cell tumor which is characterized by the remarkable proliferation and invasive growth of fibrous tissue. It often arises from the abdominal wall or the extremities and rarely from the mesentery.
Case Report: We report two cases. First was a fiftyseven year old female whose complaint was an abdominal mass without any other symptoms and undergone an operation of right hemicolectomy and ileotransversostomy after the tumor was confirmed by abominal ultrasonography (US) and abdominal computerized tomography (CT). The second was a thirtyfive year old female having a complaint of abdominal mass and undergone mass resection. Furthermore the pathophysiology ,diagnosis and the treatment of the disease is discussed.
Conclusions: In this case report we discussed the nature, primary symptoms, treatment and prognosis of the abdominal fibromatosis. After all we support, patients with fibromatosis should be treated as soon as the diagnosis and the surgical approach as the main modality as a treatment.

Keywords: Mesenteric fibromatosis, desmoid tumor, abdominal mass, surgical treatment