[Familial adenomatous polyposis, desmoid tumors and Gardner syndrome]

About 15 % of patients with familial adenomatous polyposis "PAF" develop one or more desmoid tumors in their lifetime. These are benign mesenchymal tumors with local aggressivity but with no potential for metastases. Most of the desmoids tumors result from a sporadic genetic anomaly in the β catenin gene. When related to familial adenomatous polyposis or "PAF", this mutation is not present, and the patients must be sent in genetic counselling. The PAF is a dominant autosomic illness related to a germinal mutation in the APC gene. Sometimes, these tumors can be the first manifestation of the illness. The diagnosis in a context of PAF can be easily done by imaging, but a pathological confirmation is needed. These tumors raise a therapeutic problem because of their heterogeneity and the absence of predictive biomarkers along illness evolution. The identification of prognostic biological and clinical factors would make easier the selection of patients requiring first-line treatment, as spontaneous remissions have also been observed in patients with FAP whom which an active surveillance could also be a valid therapeutic option. The particularity of desmoids tumors associated to PAF lies in their predominantly intra-abdominal location and the risk of complication. In the last ten years, surgery has largely given way to conservative treatments such as chemotherapy and more recently to tyrosine kinase inhibitors that have shown their efficacy with a significant improvement in progression-free survival of patients.