Aggressive fibromatosis, usually called desmoid tumor develops from muscle connective tissue, fasciae and aponeuroses. This neoplasm is composed of spindle (fibrocyte-like) cells. As regards the site, aggressive fibromatoses can be divided into: extra-abdominal in the area of the shoulder and pelvic girdle or chest and neck wall; abdominal in abdominal wall muscles; intra-abdominal concerning pelvis, mesentery connective tissue or retroperitoneal space. Desmoid tumor is a neoplasm which rarely turns malignant and is non-metastasizing but demonstrates ability to local infiltration into tissue and is characterized by high risk of recurrence (25-65%) after surgical treatment. Desmoid tumor etiology is uncertain. This neoplasm occurs in sporadic (idiopathic) form and is also associated with some familial neoplastic syndromes. Most sporadic cases of aggressive fibromatosis contain a somatic mutation in either the adenomatous polyposis coli (APC) or beta-catenin genes. Sporadic tumors are more frequent in women than in men from 2 : 1 to 5 : 1. In about 10-15 per cent of patients with familial adenomatous polyposis (FAP), aggressive fibromatosis is a parenteral manifestation of this familial syndrome conditioned by APC gene mutation. Abdomen injury--most frequently due to surgery is said to play an important role in the initiation of fibrous tissue proliferative process in the cases of abdominal and intra abdominal forms. High cells growth potential with relatively high local malignancy is observed in about 10% of cases with sporadic tumors as well as in those FAP-associated.