Aggressive fibromatosis, also called desmoid tumor, is a type of growth that forms in the fascia (a band of tissue under the skin) or aponeurosis (a flat sheet of tissue). This tumor is caused by too many fibroblasts (cells that help make connective tissue). It's not cancer, but it can grow into nearby tissues, making it hard to remove and likely to come back. Sometimes, doctors look at nuclear β-catenin expression and CTNNB1 gene mutation to tell it apart from other similar growths. This study will look at how these tumors develop and how surgery affects a person's quality of life. The study will analyze data from different hospitals and use specimens from past surgeries to find out what causes the tumor to come back.

• This is a retrospective study, meaning it looks at past data.
• Participants must have had surgery for this type of tumor and agree to follow-up.
• The study involves no new treatments; it's for observational analysis only.