A poorly circumscribed neoplasm arising from the soft tissues. it is characterized by the presence of spindle-shaped fibroblasts and an infiltrative growth pattern.

The term fibromatosis refers to a group of soft tissue tumors which have certain characteristics in common, including absence of cytologic and clinical malignant features, a histology consistent with proliferation of well-differentiated fibroblasts, an infiltrative growth pattern, and aggressive clinical behavior with frequent local recurrence. It is classed by the World Health Organization as an intermediate soft tissue tumor related to the sarcoma family...