Desmoid tumors (DT) (=aggressive fibromatosis) are histologically benign but locally invasive with a high recurrence rate. DT doesn´t metastasize but it can nearly affect all parts of the body (extremities (including pelvic and shoulder girdles), trunk (mostly abdominal wall) and abdominal cavity (mostly within the mesentery of the pelvis) ). Especially in the extremities a DT tends to multifocal growing. The clinical course is often unpredictable and varies a lot.

Desmoid tumors are a rare tumor entity seen in about 3-4 cases per 1 million of the population per annum. DT occurs mainly between the age of 15 and 60 years with a peak age of about 30 years.

In Desmoid tumors we have to differentiate between sporadic desmoid tumors and desmoid tumors connected to familial adenomatous polyposis (FAP). Most desmoid tumors occur sporadically only 5-10 percent of all DT arise in the context of FAP. Young adults, especially femals often related to pregnancy are more affected by sporadic DT. In older patients there is no gender preference.